Low fasting serum insulin in Japanese alcohol consumers does not imply improved coronary risk factors

The effects of alcohol consumption on coronary risk factors (CRFs) and insulin resistance (IR) have seemed equivocal in previous studies. This study aimed to clarify the implications of low fasting blood insulin observed in alcohol consumers as related to CRFs and IR.

A cross-sectional observation in 2133 middle-aged healthy Japanese men for associations of increases in alcohol consumption, fasting serum insulin concentration and serum gammaglutamyltransferase (GGT) activity with the major CRFs of high systolic blood pressure (SBP), fasting serum glucose, triglycerides (TG), total- and LDL-cholesterol (tCh&LDLc) and low serum HDL-cholesterol (HDLc).

Increased alcohol consumption was related to higher SBP, serum GGT, glucose and HDLc, and lower serum LDLc and insulin. Although high serum insulin was significantly related to all of the CRFs in all nondrinkers, moderate drinkers consuming up to 59 ml of alcohol per day and excessive drinkers consuming more, the means of SBP, serum glucose and HDLc were significantly higher and serum LDLc was lower in drinkers than in nondrinkers at any level of serum insulin, indicating that the good and bad profiles of CRFs in alcohol consumers are independent of their low fasting serum insulin. High serum GGT related to increased alcohol consumption and/or body weight was significantly associated with high serum insulin and all of the CRFs in all categories of alcohol consumption.

Low fasting serum insulin observed in drinkers does not imply improved CRFs, and thus may not imply improved IR. High serum GGT may reflect increased IR in both drinkers and nondrinkers.