The effects of tree nuts on risk factors for coronary heart disease (CHD), in particular blood lipids, have been investigated in a number of studies and the beneficial effects are now recognized. The beneficial effects of nuts on CHD in cohort studies have also been clearly demonstrated. However, while there is also reason to believe the unique micro- and macronutrient profiles of nuts may help to control blood glucose levels, relatively few studies have investigated their role in diabetes control and prevention. Nuts are low in available carbohydrate, have a healthy fatty acid profile, and are high in vegetable protein, fiber and magnesium. Acute feeding studies indicate that when eaten alone nuts have minimal effects on raising postprandial blood glucose levels. In addition, when nuts are consumed with carbohydrate rich foods, they blunt the postprandial glycemic response of the carbohydrate meal. Despite the success of these acute studies, only a limited number of trials have been conducted with nuts in type 2 diabetes. These studies have either been of insufficient duration to observe changes in HbA1c, as the standard measure of glycemic control, or have been underpowered. Therefore, more long-term clinical trials are required to examine the role of nuts on glycemic control in patients with prediabetes and diabetes. Overall, there are good reasons to justify further exploration of the use of nuts in the prevention of diabetes and its micro- and macrovascular complications.