Circadian variation of glucose, insulin, and free fatty acids during long-term use of oral hypoglycaemic agents in diabetes mellitus.

The circadian rhythms of preprandial and postprandial blood glucose, free fatty acids, and insulin levels were measured in groups of normal and of diabetic patients controlled by diet alone or by diet with tolbutamide, chlorpropamide, or metformin. All groups showed a greater insulin release after the first meal of the day than after subsequent meals. Diabetic patients controlled for more than two years on diguanide therapy showed the closest resemblance to non-diabetic control subjects. There was no significant difference between the values for diabetic patients on long-term control with diet alone and those on short- or long-acting sulphonylurea. The circadian rhythms disappeared in obese subjects on total starvation.