Diabetes mellitus. Distinguishing between patients receiving insulin and those requiring insulin therapy.

Fifteen patients with maturity onset type diabetes, all of whom had received insulin for periods of one to thirty-five years, were admitted to hospital and insulin treatment was discontinued. Within 24 to 48 hours each patient was given an intravenous tolbutamide test, following which all were given either diet therapy alone or diet therapy plus oral agents. If significant hyperglycemia or ketonemia resulted, insulin therapy was reinstituted. Approximately 50 percent (8 of 15) of the patients showed improvement in fasting blood sugar levels following discontinuation of insulin. It was not possible to distinguish the insulin independent from the insulin dependent group using such criteria as age, sex, degree of overweight, insulin dosage, duration of diabetes or duration of insulin therapy. However, using the intravenous tolbutamide test it was possible to differentiate between the two groups. Those who did not require insulin responded to intravenous tolbutamide with a glucose decrease greater than 10 percent from the initial value. The insulin dependent group had either no glucose decrease or a rise in blood glucose following intravenous administration of tolbutamide.