Diabetes

Prediabetes and Diabetes Type 2: Screening and Making the Diagnosis

Clinical Actions:

Diabetes results when the pancreas cannot respond to or produce insulin, leading to abnormal metabolism of carbohydrates and elevated levels of glucose in the blood and urine. Type 2 diabetes (previously “noninsulin-dependent diabetes” or “adult-onset diabetes”) accounts for 90–95% of all diabetes. Type 2 diabetes is caused by a progressive loss of β-cell insulin secretion, usually associated with insulin resistance. Prediabetes is diagnosed when glucose levels start to rise due to β-cell insulin secretion failure, but diagnostic criteria are not yet met for Type 2 diabetes.

Evaluate Patients for Risk Factors
Screening and Diagnostic Criteria
Symptoms of Diabetes (related to hyperglycemia)
Complications of Type 2 Diabetes

Evaluate Patients for Risk Factors

Risk Factors for Type 2 Diabetes (NIDDK)

Overweight or obese
- NIDDK BMI chart (see ‘Primary Sources – Learn More’ below)
  - Not Asian American or Pacific Islander: At-risk BMI ≥ 25
  - Asian American: At-risk BMI ≥ 23
  - Pacific Islander: At-risk BMI ≥ 26
≥45 years
Family history of diabetes
Race/Ethnicity
- African American, Alaska Native, American Indian, Asian American, Hispanic/Latino, Native Hawaiian, or Pacific Islander
Hypertension (or on therapy for hypertension)
Dyslipidemia
Personal history of
- Pregnancy: GDM or macrosomia (BW >4000 g)
- Physical inactivity
- Heart disease or stroke
- Depression
- PCOS
- Acanthosis nigricans
- HIV

Screening and Diagnostic Criteria

Who and When to Screen

ADA

Overweight or obesity (BMI ≥25 kg/m2 or ≥23 kg/m2 in Asian Americans) and ≥1 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 (≥140/90 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)
- Women with polycystic ovary syndrome
- Physical inactivity
- Other clinical conditions associated with insulin resistance (e.g., severe obesity, acanthosis nigricans)
People with HIV
- Screen for diabetes and prediabetes with a fasting glucose test
  - Before starting antiretroviral therapy
  - At the time of switching antiretroviral therapy
  - 3 to 6 months after starting or switching antiretroviral therapy
- If initial screening results are normal, fasting glucose should be checked annually
Patients with prediabetes (A1C ≥5.7% [39 mmol/mol], IGT, or IFG) should be tested yearly
Women who were diagnosed with GDM should have lifelong testing at least every 3 years
For all other patients, testing should begin at age 35 years
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

AACE/ACE

Begin at age 45 without risk factors
Screening based on risk factors: In addition to the above list, AACE/ACE includes the following factors
- Antipsychotic therapy for schizophrenia and/or severe bipolar disease
- Chronic glucocorticoid exposure
- Sleep disorders (e.g., obstructive sleep apnea, chronic sleep deprivation, and night shift occupation) with glucose intolerance
Normal glucose values: Every 3 years
Consider annual screening for patients with 2 or more risk factors

USPSTF

Screen for prediabetes and type 2 diabetes in adults aged 35 to 70 years who have overweight (BMI ≥25) or obesity (BMI ≥30)
Clinicians should offer or refer patients with prediabetes to effective preventive interventions
Above are Grade B recommendations: Offer or provide this service

Diagnostic Criteria

Normal
- Fasting plasma glucose (FPG) <100 mg/dL (5.6 mmol per L)
- Oral glucose tolerance test (OGTT) with 75g glucose load
  - 2h (plasma glucose) PG <140 mg/dL (7.8 mmol per L)
High Risk for Diabetes (prediabetes)
- Impaired fasting glucose (IFG): FPG ≥100 to 125 mg/dL (5.6 to 6.9 mmol per L)
- Impaired glucose tolerance (IGT): 2h PG ≥140 to 199 mg/dL (7.8 to 11.0 mmol per L)
- A1C 5.7% to 6.4%
- Note: Patients with prediabetes should be tested yearly

Diabetes: Glucose criteria are preferred for the diagnosis of DM
- FPG ≥126 (7.0 mmol per L) mg/dL
- OGTT: 2h PG ≥200 mg/dL (11.1 mmol per L)
- Random PG ≥200 mg/dL (11.1 mmol per L) with the following symptoms of hyperglycemia
  - Polydipsia | Polyuria | Polyphagia | Blurred vision | Weakness | Unexplained weight loss
- A1C ≥6.5%
- Note: Always confirm diabetes diagnosis with repeat glucose or A1C testing on another day

SYNOPSIS:

Prediabetes is not a clinical disorder but rather an important risk factor for diabetes and cardiovascular disease. While there are some differences between organizations regarding risk factors for screening and diagnostic cut-offs, all agree as to the importance of identifying those at risk for significant cardiovascular events if diabetes is left untreated. The prognosis for type 2 diabetes varies and is very dependent on glucose control.