5
➤ Diagnostic Criteria and Laboratory Interpretation
• Prediabetes is def ined as a fasting plasma glucose level of
100–125 mg/dL, a 2-hour plasma glucose level of 140–199 mg/dL, or
a hemoglobin A1c level of 5.7% to 6.4%.
➤ The diagnosis of T2DM requires one of the following criteria:
• Fasting plasma glucose ≥126 mg/dL (7.0 mmol/L)
• 2-hour plasma glucose ≥200 mg/dL (11.1 mmol/L) during an oral
glucose tolerance test
• Hemoglobin A1c ≥6.5% (48 mmol/mol)
• Or random plasma glucose ≥200 mg/dL with classic symptoms of
hyperglycemia.
➤ The oral glucose tolerance test remains the gold standard for
diagnosing glucose intolerance, though hemoglobin A1c provides
valuable information about average glycemic control over two to
three months.
➤ A Finnish Diabetes Risk Score (FINDRISC) score ≥12 indicates a
high risk of T2DM. Noninvasive biomarkers of insulin resistance,
such as the Homeostatic Model Assessment of Insulin Resistance
(HOMA-IR) >2.0, may also indicate a risk of T2DM. Most sources
suggest a cutoff of greater than 2.0 for insulin resistance;
however, some studies suggest a cutoff of greater than 2.5.
➤ The triglyceride-glucose (TyG) index had an error in its initial
publication, leading to two different formulas being used in
the literature:
• TyG = Ln (fasting triglycerides
×
fasting plasma glucose) ÷ 2; cutoff
≥4.5 = insulin resistance.
• TyG = Ln (fasting triglycerides
×
fasting plasma glucose ÷ 2); cutoff
≥8.5 = insulin resistance.
