Glucose Control Test

The blood glucose control test, or glycated haemoglobin (HbA1c), measures the percentage of haemoglobin with glucose attached, reflecting average blood sugar over the past 8 to 12 weeks. It’s used to diagnose diabetes and monitor long-term glucose control, guiding treatment adjustments. Results are reported as a percentage or mmol/mol; clinicians compare them to target ranges to assess control.

An oral glucose tolerance test (GTT) normal ranges: for nonpregnant adults after a 75 g load — fasting <100 mg/dL, 1‑hour <180 mg/dL, 2‑hour <140 mg/dL. For pregnancy (75 g OGTT) the stricter cutoffs for normal are fasting <92 mg/dL, 1‑hour <180 mg/dL, 2‑hour <153 mg/dL. Values above these suggest impaired tolerance or gestational diabetes.

To check glucose control: for home testing, wash hands, prepare meter and strip, prick the side of a finger with a lancet, apply blood to the strip, and record readings at recommended times (fasting, before meals, and 2 hours after meals). For clinic tests, follow fasting instructions for fasting glucose or oral glucose tolerance testing (samples at 0, 1 and 2 hours); HbA1c needs no fasting and shows 2–3 months’ control.

The best single test for overall glycemic control is the HbA1c glycated hemoglobin test, which reflects average blood glucose over the past 2 to 3 months and is used for diagnosis and monitoring. Self-monitoring with fingerstick glucose or continuous glucose monitoring complements HbA1c by showing day-to-day levels, variability, and hypoglycemia, guiding short-term treatment adjustments.

Five common signs of high blood glucose are: frequent urination, excessive thirst, increased hunger, unexplained fatigue, and blurred vision. Other possible indicators include slow-healing wounds, recurrent infections, and unexplained weight loss; anyone with these symptoms should check their blood sugar and consult a healthcare professional promptly for testing and treatment.

The two main glucose tests are fasting blood glucose and postprandial (or random) blood glucose. Fasting glucose is measured after at least eight hours without eating to assess baseline blood sugar. Postprandial or random tests measure glucose after a meal or at any time to evaluate how the body handles glucose. Both can be done by finger‑prick or laboratory venous samples; diagnostic thresholds differ.