The intravenous glucose tolerance test (IVGTT) was devised to eliminate some of the objections to the OGTT. Standard procedure for the IVGTT is as follows: The patient has a 3-day high-carbohydrate preparatory diet. After the FBG level is measured, a standard solution of 50% glucose is injected intravenously over a 3- to 4-minute period 0.33 gm/kg ideal body wt. Blood is obtained at 0.5, 1, 2, and 3 hours, although it would seem more informative to omit the 30-minute specimen and substitute a 1.5-hour sample. The curve reaches a peak immediately after injection (300-400 mg/100 ml [16.7-22.2 mmol/L], accompanied by glucosuria), then falls steadily but not linearly toward fasting levels. Criteria for interpretation are not uniform. However, most believe that a normal response is indicated by return to fasting levels by 1-1.25 hours. The height of the curve has no significance. Most agree that the IVGTT response is adequately reproducible. In diabetes, fasting levels are not reached in 2 hours and often not even by 3 hours. The curve in liver disease most characteristically returns to normal in 1.25-2 hours; however, some patients with cirrhosis have a diabetic-type curve. Many of the same factors that produce a diabetogenic effect on the OGTT do likewise to the IVGTT; these include carbohydrate deprivation, inactivity, old age, fever, uremia, stress, neoplasms, and the various steroid-producing endocrine diseases. There are, however, several differences from the OGTT. Alimentary problems are eliminated. The IVGTT is said to be normal in pregnancy and also in hyperthyroidism, although one report found occasional abnormality in thyrotoxicosis. The IVGTT is conceded to be somewhat less sensitive than the OGTT, although, as just noted, a little more specific.