my personal edition > diabetes > news


  E-Mail this DGReview to a colleague

DGReview

Insulin-Like Growth Factor I Has Direct Effect on Glucose and Protein Metabolism in Type 1 Diabetes

In patients with type 2 diabetes, insulin-like growth factor I (IGF-I) has a direct effect on glucose and protein metabolism, reports a study from the United Kingdom.

Although data indicate that recombinant human IGF-I (rhIGF) treatment improves metabolic control, reduces insulin requirement and decreases overnight growth hormone (GH) concentrations in patients with type 1 diabetes, it remains unclear whether the efficacy of IGF-I is through direct or indirect effects on reducing GH secretion.

To determine whether IGF-I directly effects glucose, lipid and protein metabolism independent of changes in GH secretion, Helen Simpson, MD, and colleagues, St. Thomas Hospital, London, United Kingdom, used stable isotopes to examine the effects of a pulse of recombinant human GH, a subcutaneous injection of recombinant human IGF-I and placebo on glucose, lipid and protein metabolism in 7 patients with type 1 diabetes.

The effects were measured during basal insulin infusion and a hyperinsulinaemic euglycaemic clamp, and octreotide was administered to suppress endogenous GH secretion.

During the basal insulin infusion, IFG-I significantly reduced hepatic glucose production (P < .05) and protein breakdown (P < .005), and increased peripheral glucose uptake (P < .05) compared to placebo. Similar significant effects were seen during the hyperinsulinaemic euglycaemic clamp compared to placebo (P < .05, P < .005, and P < .05, respectively). No significant effect was found between IGF-I and glycerol production rate, an index of lipolysis.

Significant increases in glucose and glycerol production rates was associated with GH during basal insulin infusion compared to placebo (P < .005), but no significant differences were seen during the clamp.

These data indicate a significant direct effect of IGF-I on glucose homeostasis and decreasing protein breakdown, conclude the authors. This suggests "that circulating IGF-I may act in concert with insulin to control glucose and protein metabolism, and provides more evidence to support the use of rhIGF-I as an adjunct to insulin therapy in type 1 diabetes."
J Clin Endocrinol Metab 2004 Jan;89:1:425-32. "Insulin-like growth factor I has a direct effect on glucose and protein metabolism, but no effect on lipid metabolism in type 1 diabetes"

E-Mail this DGReview to a colleague

To print, use this version