ABSTRACT
Six cases of congenital generalized lipodystrophy have been studied at different ages from infancy to adolescence with regard to glucose tolerance, insulin secretion, and insulin sensitivity. During the first few years of life there is normal glucose tolerance. The fasting immuno-reactive insulin (IRI) levels are either slightly elevated or normal. The IRI response to glucose is exaggerated and prolonged, at least from the third year of life. Some degree of insulin resistance is already present in infancy.
From the age of 8–10 years glucose tolerance decreases rapidly. The fasting IRI levels are usually grossly elevated, while fasting plasma glucose levels are only moderately elevated or normal. The IRI responses to oral and iv administered glucose, and to tolbutamide are exaggerated; the insulinogenic indices are high. Cortisone primed glucose tolerance tests become abnormal. Insulin resistance is marked, and increases with age.
After cessation of growth at approximately 12 years of age, frank diabetes with fasting hyperglycaemia and diabetic glucose tolerance curves developed in the one patient followed beyond this age. Her fasting IRI was increased, but there was a poor IRI response to glucose stimulation, suggesting a partial exhaustion of the β-cells. Her initial IRI response to tolbutamide was still good, but not as brisk as in the younger patients. This type of diabetes is quite different from the juvenile form, and also from the diabetes of older age. It may be causally related to the lack of an adequate adipose organ necessary for the disposal of excesses of glucose, or possibly related to another anti-insulin mechanism.
Effects of glucose and meal ingestion on incretin secretion in Japanese subjects with normal glucose tolerance