Glucose Tolerance 75 Gram Dose |
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Blood glucose concentrations are tightly regulated through the coordinated actions of insulin and counter-regulatory hormones, such as glucagon and epinephrine. Diabetes mellitus is characterized by elevated plasma glucose concentrations resulting from insufficient insulin, insulin resistance, or both. Type 1diabetes accounts for less than 10% of all diabetes, while type 2 diabetes accounts for the remaining 90%. Gestational diabetes occurs in 3% of all pregnancies.
The American Diabetes Association's criteria for the diagnosis of diabetes mellitus include:
- A fasting glucose of 126 mg/dL or greater. Fasting is defined as no caloric intake for at least 8 hours.
- A casual plasma glucose of 200 mg/dL or greater plus symptoms of diabetes. Casual is defined as any time of day without regard to time since last meal.
- A 2 hour postload value of 200 mg/dL or greater after a 75 g oral glucose tolerance test.
Any of these 3 criteria can be used to diagnose diabetes. In the absence of unequivocal hyperglycemia, each must be confirmed on a subsequent day by any one of these methods.
The National Diabetes Data Group guidelines for the oral glucose tolerance test are:
- The test should be done in the morning after a 10 to16 hour fast, preceded by 3 days of diet containing at least 150 g of carbohydrate, and unrestricted physical activity.
- After obtaining a fasting specimen, a 75 g glucose loading dose is consumed over 5 minutes.
- The patient should remain seated throughout the test & may drink as much water as desired.
- Blood is drawn at 1, 2, & 3 hours after the glucose load.
- Specimens should be refrigerated after collection.
Specimen requirement is one gray top (potassium oxalate-sodium fluoride) tube of blood drawn before the glucose dose and at 1 and 2hours after the glucose challenge.
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