Impaired glucose tolerance (IGT) as well as diabetes mellitus (DM) are known to carry increased atherosclerotic risk. However, the mechanism is unclear. The purpose of this study is to clarify the relationship between IGT and plasma lipid as an atherosclerotic risk factor.
Fifty seven men matched for age and %IBW were divided into four groups: normal, IGT, DM and borderline group according to WHO diagnostic criteria for evaluation of 75g OGTT. DM group was newly diagnosed at start of this study. Borderline group was “not diagnosed” group which showed slightly impaired glucose tolerance. We examined plasma lipids, lipoproteins and basal insulin levels in four groups.
1) Mean plasma triglyceride and total cholesterol levels were 165* and 202mg/dl, respectively in DM group, 150* and 178mg/dl in IGT group, 135 and 180mg/dl in borderline group, and 117 and 182mg/dl in normal group (*p<0.05 vs. normal). The incidence of hyperlipemia increased with increasing degree of glucose intolerance, that is, in order of DM, IGT, borderline and normal group.
2) Plasma basal insulin level in IGT group was significantly higher than that in DM group.
3) Plasma LDL-Cholesterol level in DM and IGT group, and atherogenic index (LDL/HDL-Cholesterol ratio) in IGT, DM and borderline group were higher than in normal group, but it was not significant.
4) Only IGT group showed a tendency to have lower level of plasma HDL-Cholesterol than normal group. Plasma HDL2-Cholesterol level and HDL2/HDL3-Cholesterol ratio in DM, IGT and borderline group were lower than in normal group, but it was not significant. There was no difference in plasma HDL3-Cholesterol level in four groups.
The present results suggest that IGT and borderline group have alterations in lipid metabolism of intermediate degree between normal group and diabetic group. These alterations might partly contribute to increased atherosclerotic risk in IGT.
