L. Austin Fredrickson, MD, FACP

L. Austin Fredrickson, MD, FACP is an assistant professor of internal medicine at Northeast Ohio Medical University, where he serves as core faculty and teaches diagnostics, therapeutics, clinical skills, and health humanities. He is board-certified in general internal medicine and practices rural primary care.


Topic Overview

Diabetes mellitus remains a major public health problem as a leading cause of death and micro- and macro-vascular morbidity. The management of diabetes continues to evolve as new research, technology, and treatments allow for enhanced patient care It is vital for healthcare providers, including physicians, nurses, and pharmacists, to remain up to date with the newest diabetes care guidelines, which now incorporate inclusive language and a patient-first approach. This includes a strong understanding of both the classification and diagnosis of diabetes. This course will review the pathophysiology, classification, and diagnosis of diabetes mellitus in the context of the updated Standards of Care in Diabetes 2023 guidelines.


Accreditation Statement:


image LLC is accredited by the Accreditation Council for Pharmacy Education (ACPE) as a provider of continuing pharmacy education.


Universal Activity Number (UAN): The ACPE Universal Activity Number assigned to this activity is 

Pharmacist  0669-0000-23-094-H01-P

Pharmacy Technician  0669-0000-23-095-H01-T

Credits: 1 hour of continuing education credit


Type of Activity: Knowledge


Media: Internet/Home study Fee Information: $4.99


Estimated time to complete activity: 1 hour, including Course Test and course evaluation


Release Date: June 24, 2023 Expiration Date: June 24, 2026

Target Audience: This educational activity is for pharmacists.


How to Earn Credit: From June 24, 2023, through June 24, 2026, participants must:


Read the “learning objectives” and “author and planning team disclosures;”

Study the section entitled “educational activity;” and

Complete the Course Test and Evaluation form. The Course Test will be graded automatically. Following successful completion of the Course Test with a score of 70% or higher, a statement of participation will be made available immediately. (No partial credit will be given.)

Credit for this course will be uploaded to CPE Monitor®.


Learning Objectives: Upon completion of this educational activity, participants should be able to:


Describe the pathophysiology of diabetes mellitus

Compare and contrast categories of diabetes mellitus

Describe tests used to diagnose diabetes



The following individuals were involved in developing this activity: Austin Fredrickson, MD, FACP, Liz Fredrickson, PharmD, BCPS, and Pamela M. Sardo, PharmD, BS. Pamela M. Sardo was an employee of Rhythm Pharmaceuticals until March 2022 and has no conflicts of interest or relationships regarding the subject matter discussed. There are no financial relationships relevant to this activity to report or disclose by any of the individuals involved in the development of this activity.


© LLC 2023: All rights reserved. No reproduction of all or part of any content herein is allowed without the prior, written permission of LLC.



Diabetes mellitus is a global epidemic. It afflicts an increasing number of people each year. Early diagnosis and treatment of diabetes are crucial in reducing the risk of developing complications and improving overall health outcomes in populations and individual patients. It is vital for healthcare providers, including physicians, nurses, and pharmacists, to remain up to date with the newest diabetes care guidelines, which now incorporate inclusive language and a patient-first approach. This includes a firm understanding of the classification and diagnosis of diabetes. This course will review the pathophysiology, prevalence, classification, and diagnosis of diabetes mellitus in the context of the updated Standards of Care in Diabetes 2023 guidelines.


Prevalence and Etiology of Diabetes


Diabetes mellitus is a global epidemic affecting millions of people worldwide, with a prevalence that continues to increase yearly.1 Diabetes is a chronic disease that affects the body's ability to either produce or respond to insulin, resulting in hyperglycemia or high levels of glucose in the blood.1,2 Long-term hyperglycemia is a leading cause of cardiovascular disease, kidney failure, blindness, and lower limb amputations.2,3 Early diagnosis and treatment of diabetes are crucial in reducing the risk of developing complications and improving overall health outcomes in populations and individual patients.1


The prevalence of diabetes varies among countries. In general, low- and middle-income countries experience a more significant increase in diabetes prevalence than high-income countries.5 In the United States (US), the prevalence has steadily increased over the past few decades. In 1980, less than 5% of the US population had diabetes. By 2020, this rose to over 11%.6 In 2020, diabetes was the eighth leading cause of death in the US.7,8 An estimated 1.4 million Americans are diagnosed with diabetes each year.9 Per the Centers for Disease Control and Prevention (CDC) data, the prevalence of diagnosed diabetes does not differ greatly between men and women.6 Between 2001 and 2020, the age-adjusted prevalence of total diabetes

increased significantly among adults 18 years of age and older.6 The percentage of adults with diabetes does increase with age, with 24% of individuals age 65 years or older diagnosed compared with 3% of individuals between the ages of 18 and 44.6 Rates of diabetes also differ by race and ethnicity. This data is presented in Table 1.9


Table 1. Diabetes by Race or Ethnicity

American Indians/Alaskan Natives14.5%
Non-Hispanic blacks12.1%
Asian Americans9.5%
Non-Hispanic whites7.4%


The CDC estimates 20-36% of diabetes are undiagnosed, and undiagnosed diabetes affects 3-5% of US adults.3 However, Fang and colleagues sought to determine trends in undiagnosed diabetes using definitions more consistent with those in clinical practice.3 They found the proportion of undiagnosed diabetes cases declined between 1988 to 2020 due to improvements in detection and estimated undiagnosed diabetes affects 1- 2% of adults in the US.3 The authors did note undiagnosed diabetes is higher in specific subpopulations, including among Asian Americans, those who are overweight or obese, and those with low income or who are uninsured.3


Type 1 diabetes mellitus (T1DM) accounts for approximately 5-10% of all cases, and worldwide these cases continue to increase for unknown reasons.1 Type 2 diabetes mellitus (T2DM), the most common form of the disease, accounts for 90-95% of all diabetes cases in the US, with a prevalence in US adults of approximately 12%.7 The increase in cases of T2DM parallels the rise in obesity cases throughout the US.1


Prediabetes is a condition in which blood glucose levels are not high enough to meet the diagnostic criteria of diabetes.1 Prediabetes is common, with over a third of US adults having prediabetes. Eight out of 10 patients with

prediabetes are unaware they have it.7 Another form of diabetes, gestational diabetes mellitus or GDM, has also seen an increased prevalence.1 It is estimated to occur in ~10% of pregnancies, and up to 50% of women who develop GDM will later develop T2DM.1 There are several other, less common, types of DM, including maturity-onset diabetes of the young (MODY) and neonatal diabetes.1


Ethnic Disparities in Diabetes Prevalence


Several racial and ethnic disparities in diabetes exist.10 Racial and ethnic minority groups have higher rates of diabetes compared to the general population, and this disparity may be attributed to several factors, including genetic predisposition, cultural differences, socioeconomic status, and healthcare access.10 Minority populations often face challenges in accessing healthcare services, receiving timely diagnoses, and adhering to their treatment regimens. This can lead to poorer diabetes control, an increased risk of complications, and higher mortality rates.10 It is crucial for clinicians to understand the importance of recognizing and addressing these disparities to promote and achieve health equity and optimize the care of all patients.10


Prevalence and Public Health Impact


In the US, the public health impact of diabetes is significant, considering both the large economic burden and the negative impact on morbidity and mortality. Addressing the diabetes epidemic requires a multifaceted approach that includes prevention efforts, effective management of the disease, and addressing the disparities in diabetes prevalence and outcomes among different populations. Healthcare providers in many different facets, including pharmacists, physicians, and nurses, all play a crucial role in managing diabetes by working collaboratively to provide patient education, counseling, and medication management services. Additionally, healthcare professionals can work with community organizations to develop and implement diabetes prevention and management programs that address the unique needs of the diverse populations that they serve.

Economic Burden


Diabetes has a significant economic impact on the healthcare system and individuals with the disease. In 2017, the estimated cost of diagnosed diabetes in the United States was $327 billion, including $237 billion in direct medical costs and $90 billion in reduced productivity due to illness-related absenteeism and presenteeism.9 Individuals with diabetes have medical expenses that are approximately 2.3 times higher than those without diabetes, and the cost of managing the disease increases as complications develop.9 The financial burden of diabetes also extends to families, who may experience reduced income due to the need for caregivers to aid family members with diabetes, as well as treat the subsequent comorbidities which stem from the disease.9


Pathophysiology of Diabetes


Diabetes is a chronic, heterogeneous metabolic disorder whose underlying etiology involves many different mechanisms.1,2,11


Figure 1. Insulin and Glucagon



Diabetes’ hallmark is hyperglycemia, or elevated plasma glucose levels, due to issues with insulin secretion, insulin action, or both.2,11 In healthy individuals, the intake of carbohydrates increases blood glucose levels and stimulates incretin hormone release from the gut and insulin release from beta-cells in the pancreas.1 High insulin levels then suppress glucose production by the liver, suppress glucagon release, and trigger peripheral tissues to take up glucose.1 Insulin also has an anti-lipolytic effect, which reduces levels of free fatty acids (FFA) in the plasma.1 See the illustration of the interaction between insulin and glucagon in Figure 1.12


Pathophysiology of Type 1 Diabetes Mellitus


Type 1 diabetes mellitus (T1DM), historically referred to as insulin- dependent diabetes mellitus (IDDM), is an autoimmune disorder in which the body's immune system attacks and destroys insulin-producing beta cells in the pancreas.11 The IDDM nomenclature has been updated to T1DM as patients with T2DM may also depend on insulin but have different underlying pathophysiology and consequences to undertreatment. The destruction of beta cells in T1DM results in an absolute deficiency of insulin, which is required to transport glucose from the bloodstream into cells for energy production.11 Without sufficient insulin, glucose accumulates in the bloodstream, leading to hyperglycemia.11 The pathogenesis of T1DM involves genetic and environmental factors, with a strong association with certain HLA haplotypes.11 The onset of T1DM typically occurs in childhood or adolescence, and the disease is often diagnosed based on the presence of hyperglycemia, ketosis, and the presence of autoantibodies against beta cells.11


Pathophysiology of Type 2 Diabetes Mellitus


Type 2 diabetes mellitus (T2DM), also historically known as non-insulin- dependent diabetes mellitus (NIDDM) or adult-onset diabetes, is a metabolic disorder characterized by insulin resistance and relative insulin deficiency via beta-cell dysfunction.11 Like IDDM, the other terms of NIDDM and adult-onset diabetes are outdated, as they are descriptors of conditions and not the underlying disease itself, as patients are now developing T2DM in childhood,

or require insulin as described above. In T2DM, Insulin resistance occurs because of disrupted cellular pathways which results in muscle, liver, and adipose tissue cells becoming less sensitive to insulin.11 This insulin resistance ultimately results in decreased glucose uptake and utilization.11 A decrease in insulin sensitivity initially causes beta-cell to attempt to compensate by increasing insulin secretion.11 Over time, the resulting hyperinsulinemia cannot compensate for decreased insulin sensitivity and beta cell dysfunction also occurs.11 Unlike T1DM, T2DM usually progresses more slowly over time and is typically diagnosed later in life.10 Patients will often remain asymptomatic despite elevated glucose levels, which may be a factor in undiagnosed cases.11


Pathophysiology of Gestational Diabetes Mellitus (GDM)


GDM is diagnosed either during or right after pregnancy and is the occurrence of glucose intolerance or the development of diabetes during pregnancy.11 GDM should not be confused with pre-existing cases of diabetes in patients with diabetes who then become pregnant.11 During the late second or third trimester of a pregnancy, blood glucose levels tend to increase. If they reach levels consistent with diabetes, GDM is diagnosed.11 Risk factors for GDM include age, obesity, having a previous pregnancy with large babies, and a previous history of GDM.11


Person-First Language in Diabetes


Historically, patients with diabetes were referred to as diabetics. Recent guidelines and medical societies have emphasized using language that prioritizes the patient and not the disease.4 By labeling patients as diabetic, much like counterparts of alcoholic, addict, or epileptic, the disease takes precedence in language over the human being seeking medical attention. To that end, the current preferred terminology is to describe patients with diabetes exactly that way (a person with diabetes) and not as diabetic, which can be a difficult transition.

Classifications of Diabetes


According to the American Diabetes Association (ADA) Standards of Care 2023 Diabetes guidelines, diabetes is classified into 4 general categories (Table 2).4 The classification system is important for the appropriate diagnosis, management, and prevention of diabetes and its complications.


Table 2. Classification of Diabetes


1. Type 1 diabetes (due to autoimmune b-cell destruction, usually leading to absolute insulin deficiency, including latent autoimmune diabetes of adulthood)

2. Type 2 diabetes (due to a non-autoimmune progressive loss of adequate

b-cell insulin secretion frequently on the background of insulin resistance and metabolic syndrome)

3. Specific types of diabetes due to other causes, e.g., monogenic diabetes syndromes (such as neonatal diabetes and maturity-onset diabetes of the young), diseases of the exocrine pancreas (such as cystic fibrosis and pancreatitis), and drug- or chemical-induced diabetes (such as with glucocorticoid use, in the treatment of HIV/AIDS, or after organ


4. Gestational diabetes mellitus (diabetes diagnosed in the second or

third trimester of pregnancy that was not clearly overt diabetes prior to gestation)


The classification of diabetes is important for several reasons. First, it allows for appropriate diagnosis and treatment of the disease. Each type of diabetes has a distinct pathophysiology and requires different approaches to management. For example, T1DM requires insulin treatment for survival, whereas T2DM can often be managed initially with lifestyle modifications, oral medications, or newer injectable treatments. Second, classification of diabetes allows for an accurate estimation of disease prevalence and incidence rates, which are key for public health planning and resource allocation given the increasing prevalence and impact of this epidemic disease. It is important for clinicians to recognize the potential complexity in diagnosing diabetes and the potential for misdiagnosis; hyperglycemia occurs in multiple conditions other

than diabetes, so a firm understanding of the characteristics of each of the following diagnostic tests is key.4


Diagnosis of Prediabetes and Diabetes Mellitus Diagnostic Tests

The diagnosis of diabetes is based on the measurement of plasma glucose levels. Per the ADA, there are four diagnostic criteria for diabetes. These include a fasting plasma glucose (FPG) level, oral glucose tolerance test (OGTT), a random plasma glucose, and a hemoglobin A1c (A1C).4 All three tests are considered equally appropriate to as diagnostic screening tools.4 However, detection rates vary for these tests based on the populations and individuals being screened.4 Further, these same screening tests can be used to diagnose prediabetes. Table 3 presents criteria for the diagnosis of diabetes and table 4 presents criteria for the diagnosis of prediabetes. The screening tests are described in more detail below.4


Table 3. Criteria for the Diagnosis of Diabetes4

FPG ≥126 mg/dL (7.0 mmol/L).

Fasting is defined as no caloric intake for at least 8 h.*


2-h PG ≥200 mg/dL (11.1 mmol/L) during OGTT.

The test should be performed as described by WHO, using a glucose load containing the equivalent of 75 g anhydrous glucose dissolved in water.*


A1C ≥6.5% (48 mmol/mol).

The test should be performed in a laboratory using a method that is NGSP certified and standardized to the DCCT assay.*


Random plasma glucose ≥200 mg/dL (11.1 mmol/L).

In a patient with classic symptoms of hyperglycemia or hyperglycemic crisis

*In the absence of unequivocal hyperglycemia, diagnosis requires 2 abnormal test results from the same results from the same sample or in 2 separate test samples.

2 h PG - 2 hour plasma glucose

DCCT - Diabetes Control and Complications Trial

Table 4. Criteria for the diagnosis of prediabetes*4

FPG 100 mg/dL (5.6 mmol/L) to 125 mg/dL (6.9 mmol/L) (IFG)
2-h PG during 75-g OGTT 140 mg/dL (7.8 mmol/L) to 199 mg/dL (11.0 mmol/L) (IGT)
A1C 5.7–6.4% (39–47 mmol/mol)

IFG -impaired fasting glucose OGTT -oral glucose tolerance test 2 h PG -2 h plasma glucose

*For all 3 tests, the risk is continuous, extending below the lower limit of the range and becoming disproportionately greater at the higher end of the range


Fasting Plasma Glucose (FPG)


The fasting plasma glucose (FPG) measures the amount of glucose in the blood after a period of no caloric intake for at least 8 hours.4 The normal range for fasting plasma glucose is between 70 and 99 mg/dL.4 A result of 100 to 125 mg/dL indicates prediabetes, while a result of 126 mg/dL or higher is diagnostic for diabetes.4 Unless the patient has unequivocal hyperglycemia, a diagnosis requires two abnormal FPG tests from either the same sample or two separate test samples.4


The FPG test is reliable and easy to perform, but some factors can affect the accuracy of the results. For example, stress, illness, medications, and physical activity can all affect blood glucose levels, leading to false results.4 That is why it is important to follow the proper preparation guidelines for the FPG test, which includes avoiding food and beverages (except water) for at least 8 hours prior to the test and avoiding strenuous exercise and stressful situations during this time.4


2-hour Plasma Glucose during Oral Glucose Tolerance Test (OGTT)


The Oral Glucose Tolerance Test (OGTT) is a diagnostic test used to evaluate the body's ability to metabolize glucose. During an OGTT, the patient will fast for at least eight hours and then intake a glucose load that contains the equivalent of 75 grams of anhydrous glucose dissolved in water.4 Blood

glucose levels are then measured two hours after the glucose drink.4 Fasting and carbohydrate restriction have the potential to falsely elevate glucose levels with the OGTT.4 Because of this, it is recommended patients eat a balanced diet that contains at least 150 grams of carbohydrates for the three days prior to this test.4


The OGTT is generally safe and well-tolerated, but some patients may experience side effects such as nausea, vomiting, and dizziness due to the high glucose load. It is important for patients to follow the fasting requirements before the test to ensure accurate results.


Per the ADA, the concordance between the FPG and the 2h PG test is imperfect. When compared to both the FPG and A1C cut points, the 2 hour plasma glucose test values result in a greater number of prediabetes and diabetes diagnoses.4 If a patient has a discordance between their A1C and glucose values, the 2-hour PG is more accurate.4


Random Plasma Glucose


In patients who display classic symptoms of hyperglycemia or are experiencing a hyperglycemic crisis, a random plasma glucose level of greater than or equal to 200 mg/dl (11.1 mmol/L) can be used to diagnose diabetes.4 Unlike the fasting plasma glucose test and the oral glucose tolerance test, this test does not require the patient to fast prior to the test.4 A random plasma glucose level cannot be used to diagnose prediabetes.4


Hemoglobin A1c (A1C)


A hemoglobin A1c (A1C) level is another means by which to diagnose diabetes and prediabetes.4 An A1C level provides overall picture of a patient’s average blood glucose levels over the past 2-3 months.4 An A1C measures the percentage of hemoglobin in the blood that has glucose attached to it.4 Hemoglobin is the protein in red blood cells that carries oxygen throughout the body.4 When glucose levels are high in the blood, some of it attaches to

hemoglobin and remains there for the life of the red blood cell, which is approximately 2-3 months.4


Various factors may impact hemoglobin glycation independent of glycemia and, therefore, the interpretation of the A1C. These include hemodialysis, pregnancy, HIV treatment, age, race, ethnicity, genetic background, and hemoglobinopathies.4 While A1C can be used to screen children and adolescents for diabetes and prediabetes, the initial studies recommending A1C testing included only adults.4 Additionally, the presence of hemoglobin variants should be considered, as these have the potential to interfere with A1C measurements.4 A1C levels for African American patients who are heterozygous for the hemoglobin variant HbS may have a 0.3% lower A1C when compared to those without the trait.4 The X-linked glucose 6- phosphate dehydrogenase G202A is associated with a ~0.7-0.8% lower A1C. Even without consideration of variants, African American patients may have A1C levels lower than non-Hispanic white patients despite similar fasting and post-prandial glucose levels.4 Finally, the measurement of A1C levels is not as reliable in the following conditions and states: postpartum, HIV treatment with certain protease inhibitors and nucleoside reverse transcriptase inhibitors, and in iron-deficiency anemia.4


Using an A1C to diagnose diabetes provides several benefits over the FPG and OGTT. These include patient convenience, as fasting is not required, greater preanalytical stability, and fewer day-to-day perturbations during times of stress, illness, or changes in nutrition.4 However, obtaining an A1C is associated with higher cost, and A1C testing does have a lower sensitivity at the designated cut point.4 Using a threshold of ≥6.5%, the A1C test will diagnose only 30% of diabetes cases collectively using A1C, FPG, or the 2- hour plasma glucose.


Per ADA guidelines, the A1C test should be performed using an NGSP- certified method. When the NGSP began in 1996, it was originally called the “National Glycohemoglobin Standardization Program.”4 As this program grew and became international in scope, the official name was shortened to the acronym. The NGSP-certified method utilized should be standardized to the

Diabetes Control and Complications Trial (DCCT) reference assay.4 In doing so, missed diagnoses and misdiagnoses can be avoided.4


Confirming the Diagnosis


The ADA guidelines state that two abnormal screening test results are necessary to confirm a diagnosis of diabetes unless there is a very clear clinical diagnosis, such as in the case of a hyperglycemic crisis.4 These two results may come from the same sample or two separate test samples.4 If a second test sample will be obtained, it is recommended that the second test be performed quickly after the first.4 This second test can be the same as the initial test or a different test.4 If both tests are at or above the diagnostic threshold, for example, an A1C level of 7.0% and 6.8%, a diabetes diagnosis can be confirmed.4 However, if these two tests have conflicting results, the test which is above the diagnostic cutoff should be repeated, and the possibility of A1C assay interference should be considered.4 It is also possible that a test that resulted in an abnormal value (one above the diagnostic threshold) may produce a value below the threshold when repeated.


Screening for and Diagnosing Type 1 Diabetes Screening for Type 1 Diabetes

There have been numerous studies suggesting the measurement of islet autoantibodies in relatives of patients with T1DM can assist in identifying patients who will develop T1DM.4 One study attempted to ascertain the risk of progressing to T1DM from the time of seroconversion to autoantibody positivity in patients in Finland, Germany, and the United States.4 Five hundred and eighty-five children developed more than two autoantibodies, and of those, 70% developed T1DM in ten years, and 84% did so within fifteen years.4 Overall, the risk of T1DM increases as the number of autoantibodies detected increases.4 Currently, widespread clinical screening of asymptomatic and low-risk individuals is not recommended.4

Diagnosing Type 1 Diabetes


The presentation and diagnosis of T1DM may vary depending on the patient. Historically, children and adolescents presented with diabetes ketoacidosis, and the rates of DKA have increased over the past two decades within the US.4 Some patients may have modestly increased fasting plasma glucose levels that can then rapidly progress to DKA with the occurrence of stress.4 In contrast, some adult patients may retain enough beta cell function to prevent the occurrence of DKA for months and even years.4 Once diagnosed, they may have little to no plasma C-peptide.4


Autoimmune markers associated with T1DM include islet cell autoantibodies and autoantibodies to glutamic acid decarboxylase (GAD65), insulin, tyrosine phosphatases islet antigen (IA-2) and IA-2beta, and zinc transporter 8.4 In Stage 1 of T1DM, patients have at least two of these autoimmune markers present.4


Several genetic factors play a role in the destruction of beta-cells within T1DM, and environmental factors also have a potential role. Various syndromes associated with T1DM include the following: immune dysregulation, polyendocrinopathy, enteropathy, and X-linked syndrome.4


Type 1 diabetes mellitus can develop following the use of immunotherapies.4 These types of immune-related adverse events occur in less than one percent of patients on such therapies.4 It is more likely in patients with high-risk HLA-DR4.4


Screening for and Diagnosing Prediabetes and Type 2 Diabetes


The criteria for screening patients for prediabetes in adults, children, and adolescents are in Tables 5 and 6, respectively. Tables 5 and 6 are set forth below.

Table 5. Criteria for Screening Adult Patients for Prediabetes and Diabetes4

1. Testing should be considered in adults with overweight or obesity (BMI

≥25 kg/m2 or ≥23 kg/m2 in Asian American individuals) who have one or more of the following risk factors:

First-degree relative with diabetes
High-risk race/ethnicity (e.g., African American, Latino, Native American, Asian American, Pacific Islander)
History of CVD
Hypertension (≥130/80 mmHg or on therapy for hypertension)
HDL cholesterol level <35 mg/dL (0.90 mmol/L) and/or a triglyceride level >250 mg/dL (2.82 mmol/L)
Individuals with polycystic ovary syndrome
Physical inactivity
Other clinical conditions associated with insulin resistance (e.g., severe obesity, acanthosis nigricans)
2. People with prediabetes (A1C ≥5.7% [39 mmol/mol], IGT, or IFG) should be tested yearly.
3. People who were diagnosed with GDM should have lifelong testing at least every 3 years.
4. For all other people, testing should begin at age 35 years.
5. If results are normal, testing should be repeated at a minimum of 3-year intervals, with consideration of more frequent testing depending on initial results and risk status.
6. People with HIV

CVD - cardiovascular disease; GDM- gestational diabetes mellitus IFG -impaired fasting glucose; IGT -impaired glucose tolerance


Table 6. Criteria for Screening Asymptomatic Pediatric and Adolescent Patients for Prediabetes and Diabetes4

Screening should be considered in youth* who are overweight (≥85th percentile) or obese (≥95th percentile) and who have one or more additional risk factors based on the strength of their association with


Maternal history of diabetes or GDM during the child’s gestation
Family history of type 2 diabetes in first- or second-degree relative
Race/ethnicity (Native American, African American, Latino, Asian American, Pacific Islander)
Signs of insulin resistance or conditions associated with insulin resistance (acanthosis nigricans, hypertension, dyslipidemia, polycystic ovary syndrome, or small-for-gestational-age birth weight)

*After the onset of puberty or after 10 years of age, whichever occurs earlier



The ADA suggests prediabetes should be viewed as a risk factor for progressing to diabetes and cardiovascular disease.4 Prediabetes is associated with hypertension, dyslipidemia (high triglycerides and/or low HDL cholesterol), and obesity.4 Many studies have found a strong association between A1C levels and the subsequent diagnosis of diabetes.3 For example, patients with an A1C between 5.5% and 6.0% had a 5-year incidence between 9% and 25%.4 For those with an A1C between 6.0-6.5%, this 5-year risk is 25% to 50%.4 The ADA has a screening tool for determining the appropriateness of screening for prediabetes.4


Type 2 Diabetes Mellitus


Unlike in T1DM, autoimmune destruction of beta cells does not occur and DKA rarely occurs.4 Due to the gradual development of hyperglycemia, it may be years before T2DM is properly diagnosed.4 Risk factors for the development of T2DM include age, obesity, and a lack of physical activity. Patients with polycystic ovarian syndrome or a history of gestational diabetes mellitus (GDM) are more likely to develop T2DM.4 If adult patients do not have the traditional risk factors for T2DM, islet autoantibody testing can be done to exclude a T1DM diagnosis.4


Screening Asymptomatic Adults


Healthcare professionals are encouraged to utilize validated screening tools for prediabetes and T2DM. The pre-symptomatic phase prior to the diagnosis of T2DM can be long, and the longer the duration of hyperglycemia, the stronger the risk of adverse outcomes.4 Screening is also beneficial in that identifying prediabetes allows for interventions to prevent the profession of diabetes. In doing so, there is a much lower risk of developing long-term complications such as retinopathy.4 An appropriate screening test interval is not clear. It is currently recommended to screen every three years as the number of false-positive tests will be reduced, and false-negative tests can be

redone before any complications develop.4 Higher-risk individuals may benefit from shorter intervals between screenings.4


Patient Counseling


Every patient with diabetes is unique and benefits from an individualized and patient-centered approach. The ADA recommends that all people with diabetes participate in diabetes self-management education.4 Diagnosis is a critical time to evaluate the need for diabetes self-management education and support, which certified diabetes educators can give. Still, it can also be supported by other health professionals, including pharmacists, pharmacy technicians, physicians, and nurses.4 In addition to learning about diabetes and its management, all healthcare team members can relay several important concepts. Patients can be advised to:


Ask questions at any time. The answers can be very important.

Use reputable resources when getting medical information about diabetes, including from their treating healthcare team or the American Diabetes Association.

Not become stressed about potential misinformation they may find from internet sources or laypersons.

Not compare diabetes tests and management to their friends or family, as each patient's situation is unique.


Patients may need to know some basic facts about diabetes as well.

These include the following:


Compare the different types of diabetes, and that each person’s course is unique.

Some medications can induce or worsen diabetes.

Diet and lifestyle optimization is the foundation of diabetes management.

It is critical to display compassion when communicating with patients, especially when they may be overwhelmed by the implications of their diabetes. Allow time for patients to consider what is being discussed and use teach-back to ensure patient comprehension.




Diabetes is a prevalent and serious public health issue within the United States. The early and correct diagnosis and management of diabetes are essential to prevent the development and progression of complications associated with the disease. Several diagnostic tests are available for the diagnosis of diabetes, including fasting plasma glucose, the oral glucose tolerance test, random plasma glucose, and hemoglobin A1C. It is important to consider the patient's clinical presentation and risk factors in interpreting the results of these tests. In addition, screening for diabetes in patients who are at increased risk for the disease can help identify cases of diabetes early and prevent the development of complications.


It is vital healthcare providers, including physicians, nurses, and pharmacists, remain up to date with the newest diabetes care guidelines, which now incorporate inclusive language and a patient-first approach. This includes a firm understanding of the classification and diagnosis of diabetes.

Course Test


Which of the following statements regarding the prevalence of diabetes mellitus (DM) is most correct?


True prevalence if DM is lower than measured because diabetes diagnostic criteria are commonly falsely positive

True prevalence of DM is higher than measured incidence due to patients who have DM but are undiagnosed*

Diabetes prevalence is higher in the younger population than the older population

There are fewer diagnosed cases of diabetes than 10 years ago


Which of the following racial/ethnic groups has the highest prevalence of diabetes?


American Indians/Alaska Natives

Non-Hispanic blacks


Non-Hispanic whites


Which of the following correctly describes Gestational Diabetes?


It is due to autoimmune b-cell destruction, usually leading to absolute insulin deficiency

It is due to a non-autoimmune progressive loss of adequate b-cell insulin secretion frequently on the background of insulin resistance and metabolic syndrome

It is diabetes diagnosed in the second or third trimester of pregnancy that was not clearly overt diabetes prior to gestation

It is due to drugs or chemicals that induce diabetes


Which of the following correctly describes Type 2 diabetes?


It is due to autoimmune b-cell destruction, usually leading to absolute insulin deficiency

It is due to a non-autoimmune progressive loss of adequate b-cell insulin secretion frequently on the background of insulin resistance and metabolic syndrome

It is diabetes diagnosed in the second or third trimester of pregnancy that was not clearly overt diabetes prior to gestation

It is due to drugs or chemicals that induce diabetes

Which criteria does the American Diabetes Association cite as diagnostic for diabetes?


FPG ≥70 mg/dL

A1c ≥ 5.7%

Random plasma glucose >200 mg/dL in a patient with classic symptoms of hyperglycemia or a hyperglycemic crisis

Random plasma glucose >100 mg/dL


Which criteria does the American Diabetes Association cite as diagnostic for prediabetes?


FPG <50 mg/dL

A1c ≥ 5.7%

Random plasma glucose >200 mg/dL

GAD65 autoantibodies


Patients with an overweight or obese BMI should be considered for testing if they have which of the following risk factors?







How often should patients with prediabetes be tested for diabetes?


Every year

Every 3 years

Every 5 years

Only if the patient develops symptoms


At what age should patients without any known risk factors for diabetes begin screening for diabetes?


25 with rechecks every 5 years if results are normal

35 with rechecks every 3 years if results are normal

45 with rechecks every 2 years if results are normal

55 with rechecks every year if results are normal

The hemoglobin A1C level estimates the average glucose over which of the following time periods?


1-2 months

2-3 months

1 year




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