Studies in congenital generalized lipodystrophy. IV. Effect of muscular exercise on carbohydrate and fat metabolism including plasma levels of IRI and HGH.

Two patients with congenital generalized lipodystrophy have been studied at rest, and during and after long-term exercise at different carefully measured work loads. The two patients represented different stages of diabetes development. Both patients derived most of their energy used during muscular exercise from carbohydrate, and comparatively little from fat. FFA levels remained low throughout the period of observation in contrast to normal individuals and patients with juvinile diabetes. The data presented seem to show that deposition of glucose and free fatty acids (FFA) as triglyceride, must be impaired and are not compatible with the concept of increased triglyceride turnover in the adipocytes. The fall in blood glucose concentration (BCG) was less than in normal individuals and juvenile diabetes during exercise, and the glucose tolerance remained unchanged following work stop in both patients (k-values unchanged), in contrast to normal persons and patients with juvenile diabetes. Both patients showed significant falls in circulating immuno-reactive insulin (IRI) levels during exercise irrespective of a rise or fall in BGC. Thus, the exercise itself might activate endogenous mechanisms which could, on the one hand increase the circulating BGC, and at the same time force circulating IRI to decrease, thus disturbing the well-known relationship between circulating glucose and IRI levels as has been exhibited in normal subjects. The high IRI levels, also during exercise in these patients, indicate a relative insulin resistance in the muscles, but less marked than the insulin resistance in the adipose tissue. The IRI response after glucose infusion did not change significantly with increasing work loads with one exception. Exercose did not alter significantly the human growth hormone (HGH) levels in either the diabetic or the non-diabetic patient indicating an abnormal regulation of the HGH secretion in congenital lipodystrophy.