Moderate alcohol consumption is associated with a reduced risk of type 2 diabetes. There are several possible biological mechanisms that may explain the observed relationship. Development of insulin resistance is a key factor in the pathogenesis of type 2 diabetes [76] and the risk reduction may be explained by an increase in insulin sensitivity after moderate alcohol consumption [77] which has been found in observational studies [78-80] as well as randomized controlled trials [81;82]. Alternatively, ethanol oxidation produces measurable downstream metabolites such as acetaldehyde and acetate [83] which may reduce the risk of type 2 diabetes. Moderate alcohol consumption is also known to increase high density lipoproteins (HDL) cholesterol concentrations [84], although at higher consumption levels, body weight, triglyceride concentration, and blood pressure may increase ([85;86]; see also IHD below). Another plausible protective mechanism is through the anti-inflammatory effect of alcohol [87;88]. However, whether moderate alcohol intake is itself a protective factor for diabetes or whether it is a marker for other healthy lifestyle choices is not certain. We decided to include diabetes into the CRA as causally impacted by alcohol consumption, but the overall level of evidence for this was considered as borderline between sufficient and limited.
