Serum adiponectin in young adults--interactions with central adiposity, circulating levels of glucose, and insulin resistance: the CARDIA study.

Purpose: To study adiponectin, a circulating adipocytokine secreted by adipocytes inversely associated with diabetes and insulin resistance, and factors affecting its levels in the Coronary Artery Risk Development in Young Adults (CARDIA) study.

Methods: Adiponectin in serum was measured by radioimmunoassay in 3355 participants (ages: 23-45 years) categorized by fasting glucose levels as normal, impaired fasting glucose, or diabetes mellitus.

Results: Levels of adiponectin were higher in women, in white participants, and with age. Waist circumference, estimating visceral fat, strongly and inversely correlated with levels of adiponectin, more than body mass index. Adiponectin values adjusted for gender and race were lower with higher fasting glucose values in the normal range and still lower with impaired fasting glucose and untreated diabetes mellitus, even further adjusting for waist circumference and fasting insulin levels (p < 0.0001). Gender- and race-adjusted adiponectin levels were inversely associated with insulin resistance at year 15 and with insulin resistance measured 15 years previously and with its change from baseline to year 15 (p < 0.0001).

Conclusions: These data suggest complex and significant physiologic interactions among circulating levels of adiponectin and measures of insulin action throughout young adulthood, even from several years earlier. Central obesity, as measured with waist circumference, is a primary factor affecting levels of circulating adiponectin. Furthermore, levels of glucose and levels of adiponectin may directly influence one another.