Objective: To study the correlation between the changes in homocysteine (Hcy) levels during hyperinsulinemia and insulin sensitivity.
Material and Method: Forty-five subjects who underwent hyperinsulinemic euglycemic clamp were studied. Twenty-five subjects had normal glucose tolerance, seven had impaired glucose tolerance, and 13 had type 2 diabetes mellitus. Serum Hcy was measured before (Hcy 0) and at 120 minutes (Hcy 120) of glucose clamp. The change in Hcy levels during hyperinsulinemia was expressed as absolute difference between Hcy 0 and Hcy 120 (ΔHcy) and percentage difference over Hcy 0 (%ΔHcy). Insulin sensitivity index (ISI) was used to correlate with variables of interest.
Results: The ISI was not correlated with Hcy 0 and Hcy 120 but was correlated with ΔHcy and %ΔHcy. The ΔHcy and %ΔHcy were not significantly different between subjects with normal and abnormal glucose tolerance, whereas they were significantly different between subjects whose ISI were above and below the mean value.
Conclusion: Although the change in Hcy levels during hyperinsulinemia was correlated with insulin sensitivity, the Hcy levels per se were not found to be correlated with insulin sensitivity. The change in Hcy levels during hyperinsulinemia was significantly different in subjects whose ISI was above and below the mean value but not in subjects with normal and abnormal glucose tolerance. This indicated that insulin resistance, not the glucose tolerance status, affected Hcy metabolism.

Keywords: Homocysteine, Hyperinsulinemia, Insulin sensitivity