Circulating endothelin-1 levels increase during euglycemic hyperinsulinemic clamp in lean NIDDM men

Area of Science:

• Endocrinology
• Vascular Biology
• Metabolic Syndrome

Background:

• Endothelin-1 (ET-1) is a potent vasoconstrictor peptide.
• Insulin resistance is a hallmark of non-insulin-dependent diabetes mellitus (NIDDM).
• The relationship between insulin and ET-1 secretion in NIDDM requires further elucidation.

Purpose of the Study:

• To investigate whether insulin administration stimulates endothelin-1 (ET-1) secretion in vivo in individuals with NIDDM.
• To explore the correlation between insulin levels and ET-1 secretion.
• To assess the potential impact of ET-1 on insulin sensitivity.

Main Methods:

• A randomized crossover study involving 16 lean, normotensive men with NIDDM.
• Euglycemic hyperinsulinemic clamp (40 mU insulin.m-2.min-1) or placebo infusion was administered for 2 hours.
• Plasma ET-1 levels were measured at baseline, during clamp/placebo, and during recovery.

Main Results:

• Circulating ET-1 levels significantly increased during the hyperinsulinemic clamp compared to placebo (P < 0.0001 at 60 and 120 min).
• A significant positive correlation was observed between basal insulin levels and ET-1 levels (r = 0.771, P < 0.0001).
• A negative correlation between total glucose uptake and baseline ET-1 levels suggests impaired insulin sensitivity (r = -0.498, P < 0.05).

Conclusions:

• Insulin administration significantly elevates circulating ET-1 levels in men with NIDDM.
• Elevated ET-1 may exert detrimental effects on insulin sensitivity in target tissues.
• Increased ET-1 release, potentially stimulated by insulin, could contribute to diabetes-related vascular complications.