not strictly paleo but what the heck...

After controlling for possible confounders of age, body mass index, family
history of diabetes, physical activity and smoking, multivariate analysis
demonstrated that men who consumed 30.0 to 49.9 g of alcohol daily (about
two and a half to four and a half glasses of wine) had a relative risk  of
0.61 (95% confidence interval 0.44 to 0.91) compared with abstainers.
http://www.medicalfriendsofwine.org/diabetesinsulin.html

andrew