Exaggerated somatomedin-C response to human growth hormone infusion in patients with type II diabetes mellitus.

The suggestion of a role for the abnormally regulated growth hormone (GH) in the pathogenesis of diabetes mellitus (DM), implicates also the somatomedins, as mediators of some of GH actions. The present study was aimed at assessing the somatomedin response to exogenous GH administration in diabetes type II (NIDDM) subjects as well as its possible relationship with the degree of control of diabetes. Twenty-two subjects (seven controls and 15 NIDDM patients), matched for sex and age, underwent human GH infusion (0.1 U/kg b.w.) over a one-hour period (time 0 to 1 hour). Total somatomedins (SMs) were measured by human placental membrane radioreceptor assay (in which all SMs crossreact) and Somatomedin-C (SM-C) was determined by a specific RIA. Values were obtained from plasma samples at times 0, 1, 4, 6, and 24 hours. Glycosylated hemoglobin (HbA1a-c) measurements were done from blood samples obtained at time 0. The increase in SMs following GH infusion in NIDDM group was not significantly different from that of the controls. In contrast, the SM-C increase at time 6 and 24 hours were significantly higher than in controls (p less than 0.05 and p less than 0.01, respectively). No significant difference was found between SMs or SM-C response to GH infusion in patients with HbA1a-c greater than 10% vs. less than 10%. These results indicate an exaggerated and prolonged increase in SM-C synthesis following exogenous GH infusion in NIDDM subjects, apparently unrelated to the degree of control of diabetes.