We examined the in vivo metabolic effects of vanadyl sulfate (VS) in non-insulin-dependent diabetes mellitus (NIDDM). Six NIDDM subjects treated with diet and/or sulfonylureas were examined at the end of three consecutive periods: placebo for 2 wk, VS (100 mg/d) for 3 wk, and placebo for 2 wk. Euglycemic hyperinsulinemic (30 mU/m2.min) clamps and oral glucose tolerance tests were performed at the end of each study period. Glycemic control at baseline was poor (fasting plasma glucose 210 +/- 19 mg/dl; HbA1c 9.6 +/- 0.6%) and improved after treatment (181 +/- 14 mg/dl [P < 0.05], 8.8 +/- 0.6%, [P < 0.002]); fasting and post-glucose tolerance test plasma insulin concentrations were unchanged. After VS, the glucose infusion rate during the clamp was increased (by approximately 88%, from 1.80 to 3.38 mg/kg.min, P < 0.0001). This improvement was due to both enhanced insulin-mediated stimulation of glucose uptake (rate of glucose disposal [Rd], +0.89 mg/kg.min) and increased inhibition of HGP (-0.74 mg/kg.min) (P < 0.0001 for both). Increased insulin-stimulated glycogen synthesis (+0.74 mg/kg.min, P < 0.0003) accounted for > 80% of the increased Rd after VS, and the improvement in insulin sensitivity was maintained after the second placebo period. The Km of skeletal muscle glycogen synthase was lowered by approximately 30% after VS treatment (P < 0.05). These results indicate that 3 wk of treatment with VS improves hepatic and peripheral insulin sensitivity in insulin-resistant NIDDM humans. These effects were sustained for up to 2 wk after discontinuation of VS.
N Cohen, M Halberstam, P Shlimovich, C J Chang, H Shamoon, L Rossetti
The Editorial Board will only consider comments that are deemed relevant and of interest to readers. The Journal will not post data that have not been subjected to peer review; or a comment that is essentially a reiteration of another comment.