Circulating Insulin-Like Growth Factor I Concentrations in Clinically Severe Obese Patients With and Without NIDDM in Response to Weight Loss

Summary

Earlier studies have demonstrated decreased levels of circulating Insulin-Like Growth Factor-I (IGF-I) in patients with NIDDM and IDDM (Yde 1969; Rieu and Binoux 1985), with a return to normal in those diabetics who achieve improved metabolic control (Rieu and Binoux 1985; Ameil, Sherwin, Hintz, Gertner, Press and Tamborlane 1984) following insulin therapy. One method of improving metabolic control in clinically severe obese NIDDM patients is the gastric bypass procedure (GBP). This study revealed a significant decrease in serum IGF-I concentrations in clinically severe obese patients with NIDDM (obese NIDDM) (105 ng/dl ± 11; n = 29) as compared with clinically severe obese patients with normal glucose tolerances (obese control) (143 ± 11; n = 21) and lean controls (177 ± 14; n = 19) (p<0.001). Following a GBP, IGF-I levels increased in the NIDDM group (142 ng/dl ± 13.0; n = 20) to the extent that no significant difference was seen between postoperative NIDDM, obese controls, and lean controls. Postoperative IGF-I levels in the obese controls (151 ± 14; n = 9) revealed no difference from preoperative levels. Postoperative obese NIDDM and obese control had a 28% and 29% decrease, respectively, in weight, with no difference between the groups in respect to Body Mass Indices. The NIDDM postoperative group revealed reductions in levels of HbA₁C, insulin, and glucose concurrent with elevations in IGF-I when compared with controls. We conclude that improvement in glucose control led to the increase in IGF-I levels.

Key words

IGF-I - Diabetes - Obesity