Children with antibodies to beta cell proteins (ie, at early stages of an immune reaction to them) but no overt diabetes, and treated with vitamin B-3 (niacin), had less than half the diabetes onset incidence in a 7-year time span as did the general population, and an even lower incidence relative to those with antibodies as above, but who received no vitamin B3.

Type 2 diabetes risk can be reduced in many cases by making changes in diet and increasing physical activity. The American Diabetes Association (ADA) recommends maintaining a healthy weight, getting at least 2 1/2 hours of exercise per week (several brisk sustained walks appear sufficient), having a modest fat intake, and eating sufficient fiber (eg, from whole grains). The ADA does not recommend alcohol consumption as a preventive, but it is interesting to note that moderate alcohol intake may reduce the risk (though heavy consumption absolutely and clearly increases damage to bodily systems significantly); a similarly confused connection between low dose alcohol consumption and heart disease is termed the French Paradox.

There is inadequate evidence that eating foods of low glycemic index is clinically helpful despite recommendations and suggested diets emphacizing this approach.

There are numerous studies which suggest connections between some aspects of Type II diabetes with ingestion of certain foods or with some drugs. Some studies have shown delayed progression to diabetes in predisposed patients through prophylactic use of metformin, rosiglitazone, or valsartan. In patients on hydroxychloroquine for rheumatoid arthritis, incidence of diabetes was reduced by 77% though causal mechanisms are unclear. Breastfeeding may also be associated with the prevention of type 2 of the disease in mothers. Clear evidence for these and any of many other connections between foods and supplements and diabetes is sparse to date; none, despite secondary claims for (or against), is sufficiently well established to justify as a standard clinical approach.