Understanding Diabetes Mellitus: Blood Sugar Thresholds

Diabetes mellitus is diagnosed based on specific blood sugar (glucose) level thresholds:

- Fasting Plasma Glucose (FPG): Fasting means not consuming any calories for at least 8 hours, usually overnight.

1) Normal: Less than 100 mg/dL (< 5.6 mmol/L)

2) Impaired Fasting Glucose (IFG): 100–125 mg/dL (5.6–6.9 mmol/L)

3) Diabetes: 126 mg/dL (7.0 mmol/L) or higher

- Random Plasma Glucose (RPG): A random blood sugar test can be done at any time, regardless of when you last ate.

1) Normal: Less than 140 mg/dL (< 7.8 mmol/L)

2) Diabetes: 200 mg/dL (11.1 mmol/L) or higher

- Oral Glucose Tolerance Test (OGTT): This test measures how your body responds to sugar after consuming a glucose-containing drink. Blood sugar levels are checked over a period of several hours.

1) Normal: Fasting glucose below 100 mg/dL (5.6 mmol/L) and 2-hour glucose below 140 mg/dL (< 7.8 mmol/L)

2) Impaired Glucose Tolerance (IGT): Fasting glucose below 126 mg/dL (7.0 mmol/L) and 2-hour glucose between 140–199 mg/dL (7.8–11.0 mmol/L)

3) Diabetes: Fasting glucose 126 mg/dL (7.0 mmol/L) or higher, or 2-hour glucose 200 mg/dL (11.1 mmol/L) or higher

For most people, a single abnormal blood sugar test result does not necessarily indicate diabetes. Therefore, your doctor may recommend repeating the test or conducting additional tests to confirm a diagnosis of diabetes mellitus.