The Relation of Light-to-Moderate Alcohol Consumption to Glucose Metabolism and Insulin Resistance in Nondiabetic Adults: the Moderating Effects of Depressive Symptom Severity, Adiposity, and Sex

Due to the small number of regular drinkers (7.6%, n = 16 out of 213), we combined the occasional and regular drinking categories to form one category representative of light-to-moderate drinking. Before establishing this combined category, we examined whether the two categories, occasional and regular, differed on demographics, anthropomorphics, and depressive symptom severity. As expected, occasional drinkers (n = 70) reported fewer drinks per week (median = 0.43, IQR 0.15–1.0) relative to regular (n = 16) drinkers (median = 1.43, IQR 0.86–2.14). No subject in the regular consumption group reported drinking more than 3 drinks/day; thus, heavy drinkers (≥5 drinks/day) were no represented in this sample. Comparisons between occasional and regular drinkers did not reveal significant differences in age (F = 2.86, ns), BMI (F = 1.15, ns), educational status (F = 0.49, ns), and BDI (F = 0.14, ns). In addition, the distribution of men and women did not differ by alcohol group χ ²(1) = 0.46, ns. Using the same set of covariates as in the primary analysis (e.g., age, BMI, race, sex, educational status, and physical activity), we examined differences between occasional and regular drinkers on log(HOMA-IR), insulin, and glucose. Results showed no group differences for log(HOMA-IR) (F = 0.32, ns), insulin (F = 0.21, ns), and glucose (F = 2.29, ns).

For women, we also examined whether the BDI total score was positively associated with log (HOMA-IR) and insulin within each alcohol group. Previous studies have suggested that increases in BDI are associated with increases in insulin resistance and, to a lesser extent, increases in fasting insulin in nondiabetic adults [34, 58]. Results of analysis revealed that increasing log(HOMA-IR) was significantly associated with increasing BDI (b = 0.30, t = 2.56, p = 0.02) for nondrinkers, but not for infrequent (b = −0.70, t = −0.99, ns) and regular/occasional (b = 0.14, t = 1.38, ns) drinkers. Similarly, insulin values were significantly associated with total BDI score (b = 5.20, t = 2.46, p = 0.02) for nondrinkers, but not for infrequent (b = −0.15, t = −0.19, ns) or regular/occasional (b = 0.92, t = 0.86, ns) drinkers. Lastly, when alcohol group was used as a covariate, results of multivariate liner regression revealed positive associations between log(HOMA-IR) and BDI (b = 0.12, t = 1.93, p = 0.057) and between insulin and BDI (b = 1.85, t = 2.19, p = 0.03) for never drinkers. In drinkers, no associations between BDI and either log(HOMA-IR) or fasting insulin were observed. Combined, these findings suggest that higher levels of depressive symptom severity are associated with greater IR and fasting insulin and that these associations are significant only in women who abstain from alcohol. While we do not recommend that woman with elevated symptoms of depression begin drinking alcohol, the findings underscore the complex nature of the relationship among sex, alcohol consumption, glucose metabolism, IR, and depressive symptom severity.