Association of serum adiponectin concentration to lipid and glucose metabolism in healthy humans.

BACKGROUND: Adiponectin is a recently discovered plasma protein with many associations to glucose and lipid metabolism. Due to its central role in cardiovascular diseases and insulin resistance, we studied the relationship between serum adiponectin and factors reflecting glucose and lipid metabolism. METHODS AND RESULTS: Thirty healthy participants (20M/10F, age 32.0 +/- 2.1 years, BMI 25.8 +/- 0.9 kg/m (2) and HbA (1c) 5.2 +/- 0.1 %) were studied four times at approximately one week intervals. The effects of a 4-hour euglycemic hyperinsulinemia (40 mU/m (2)/min), saline infusion (control), oral glucose, and oral fat load on serum adiponectin were studied. No significant correlation was found between serum adiponectin and insulin sensitivity before (r = 0.25) or after adjustment for age, BMI and gender (r = 0.04). Adiponectin concentration correlated inversely with HbA (1c) (r = - 0.43, p < 0.05), insulin concentration (r = - 0.38, p < 0.05) and triglyceride concentration (r = - 0.42, p < 0.05) but positively with HDL cholesterol (r = 0.38, p < 0.05). Metabolic procedures had no effect on serum adiponectin. CONCLUSIONS: Our findings favor the interpretation that adiponectin is not causally related to insulin sensitivity in healthy participants. The strongest associations of adiponectin in healthy participants are to be found to lipid metabolism. Serum levels of adiponectin are very stable and not acutely affected by hyperinsulinemia, oral glucose or fat load.