A novel index of insulin resistance determined from the homeostasis model assessment index and adiponectin levels in Japanese subjects

Insulin resistance is the principal cause of glucose intolerance and type 2 diabetes and induces progression of severe atherosclerosis in these patients. Adiponectin, the adipose-specific proteins, is known to correlate negatively with insulin resistance in patients with obesity and type 2 diabetes. The purpose of this study was to evaluate the potential of using serum adiponectin levels as a marker of insulin resistance in various states of insulin resistance. Furthermore, we attempted to establish a modified index of the homeostasis model assessment index (HOMA-IR), calculated from the product of serum insulin and plasma glucose levels divided by serum adiponectin levels (HOMA-AD).We recruited 117 Japanese subjects with various degrees of glucose tolerance and determined serum adiponectin levels and insulin sensitivity (M-value) by using the euglycemic hyperinsulinemic clamp technique. M-value, the gold standard index of insulin resistance, correlates significantly and independently with fasting insulin (r = −0.313, P < 0.001), glucose (r = −0.319, P < 0.001), and adiponectin (r = 0.241, P < 0.002) levels. M-values were more significantly correlated with HOMA-AD (r = −0.643, P < 0.001) than HOMA-IR values (r = −0.591, P < 0.001). In subjects with moderate hyperglycemia (fasting glucose levels > 8.0 mmol/L, n = 30), HOMA-AD showed a more significant correlation with the M-value than HOMA-IR (r = −0.535, P = 0.005 versus r = −0.461, P = 0.010).We would therefore like to propose a novel index, HOMA-AD, as a simple and adequate index for determining insulin resistance even in diabetic patients with overt hyperglycemia.