- 8 to 10 hours of overnight fasting is required for fasting plasma glucose (FPG) estimation. Not more not less.
- Usual night’s food; no less no more.
- Diabetic drugs or insulin, if prescribed for night should also be taken as usual.
- Fasting state in the morning is required, no insulin or drugs in the morning before giving first sample of blood for fasting glucose estimation; one glass of water can be allowed in the morning.
- Take usual or equivalent diet as taken in the lunch time with drugs/insulin, if already prescribed for diabetes; give second blood sample after 1 hour or 2 hours as advised; for post prandial blood glucose (PPGS) estimation.
- Alternatively 75 grams of glucose mixed in two glasses of water drunk within 5 minutes; can be substituted for the the food in PPGS estimation.
- Venous blood is ideal for plasma glucose estimation; preferably collected from a vein in between forearm and arm.
Interpretation goes like this;
NORMAL -- GLUCOSE INTELERANT - DIABETES
FPG…Less than110 mg% …… 110 to 126 mg%………….. More than 126 mg%
PPGS Less than140 mg%………140 to 180/200 mg%…. More than 200 mg%
Glucose Oxidase method in the best method for estimation of plasma glucose.
Random plasma glucose estimation should not be relied for diagnosis of new diabetes.
Diabetes mellitus is never diagnosed on urine sugar estimation.
At present glycosylated haemoglobin (HAc1) also not used to diagnose new diabetes mellitus.
Testing at least three different occasions required to diagnose new diabetes mellitus.