The diagnosis of diabetes is mainly based on the values of Fasting Plasma Glucose (FPG), 2-hour Plasma Glucose in Oral Glucose Tolerance Test (OGTT), and Glycated Hemoglobin (HbA1c).
Diabetes can be diagnosed if:
Fasting blood glucose ≥ 7.0 mmol/L, OR
2-hour OGTT blood glucose ≥ 11.1 mmol/L, OR
HbA1c ≥ 6.5%,
after excluding other interfering factors.
Below are the normal values, diabetic values, and prediabetic values used for diagnosis:
- Fasting Plasma Glucose (FPG)
Fasting means no calorie intake for at least 8 hours.
Normal: < 6.1 mmol/L
Diabetic: ≥ 7.0 mmol/L
Impaired Fasting Glycemia (prediabetes): 6.1–6.9 mmol/L - 2-hour OGTT Plasma Glucose
Measured 2 hours after drinking 75g of glucose solution.
Normal: < 7.8 mmol/L
Diabetic: ≥ 11.1 mmol/L
Impaired Glucose Tolerance (prediabetes): 7.8–11.0 mmol/L
Sometimes, repeated testing is required to confirm a diabetes diagnosis.