What dietary patterns can help prevent and manage type 2 diabetes?

This review examined the role of diet and nutrition in preventing and managing type 2 diabetes (T2D). Diets rich in whole grains, fruit, vegetables, nuts, legumes and low in refined grains, processed meats and sugar sweetened beverages (SSBs) reduced the risk of developing diabetes and were beneficial for management of existing diabetes. 

Obesity, sedentary lifestyles and increased consumption of high-calorie, refined, processed food has contributed to the large increase in T2D worldwide. Healthy diet patterns can reduce the risk of developing T2D and improve management of existing T2D.

This review examined the various dietary patterns and individual nutrients which may impact the risk of diabetes and help manage existing diabetes.

High BMI (body mass index; measure of body fat) and waist circumference both increase risk of T2D. Weight loss and exercise programs reduce the risk of diabetes by 58% in those at high risk. Weight loss improves quality of life for T2D patients and reduces medication requirements.  

Replacing saturated fat (fatty meat, butter and baked goods) with plant-based fats, especially poly-unsaturated fatty acids (PUFAS; vegetable oils and nuts) can reduce diabetes risk. Patients with T2D are advised to reduce saturated fat and trans fat (also called hydrogenated oil) and increase fish and PUFA consumption.

White rice and red meats, especially processed meats such as hot dogs, sausages and bacon are associated with increased diabetes risk. High fiber, whole grain carbohydrates and low glycemic index (GI; foods that do not rapidly increase blood glucose levels) carbohydrates lower diabetes risk. They also improve blood glucose control in T2D patients.

Green leafy vegetables, grapes, apples and blueberries are associated with decreased diabetes risk. Dairy (yogurt particularly) and nut consumption, especially walnuts, may decrease diabetes risk. In T2D patients, following a Mediterranean diet (high in vegetables, whole grains, and olive oil, low in saturated fats) was associated with improved blood glucose control and lowered cardiovascular (heart) risk. Patients trying to lose weight should not decrease their intake of protein in order to prevent muscle loss.

Reducing SSBs and added sugar is recommended for T2D patients or those at risk. Instead, water, tea or coffee are recommended. Excess alcohol consumption is also associated with increased diabetes risk. Moderate alcohol consumption is recommended. 

This review concluded that a diet rich in fruits, vegetables, whole grains, nuts, legumes and low in processed and red meats, SSBs and refined grains is associated with reduced risk of diabetes and is beneficial in the management of diabetes. 

The majority of guidelines are based on research in Western populations.