Which of the following 2 hour postprandial glucose value demonstrates unequivocal hyperglycemia diagnostic for diabetes mellitus?

• A. 160 mg/dL (8.8 mmol/L)
• B. 170 mg/dL (9.4 mmol/L)
• C. 180 mg/dL (9.9 mmol/L)
• D. 200 mg/dL (11.0 mmol/L)

Answer: (D)

In diagnosing diabetes with an oral glucose tolerance test, the key measure is the 2-hour postload plasma glucose after a 75 g glucose drink. A value of 200 mg/dL (about 11.1 mmol/L) or higher at 2 hours is diagnostic for diabetes, regardless of symptoms in the OGTT framework. Values below that threshold fall into normal or impaired glucose tolerance categories: typically, 140–199 mg/dL indicates impaired glucose tolerance (prediabetes), and below 140 mg/dL is normal. Therefore, 200 mg/dL at 2 hours is the unequivocal diabetes threshold, while the lower values do not alone confirm diabetes.