Both vegetarian and vegan diets can be healthful diets and can be part of a dietary strategy to control blood glucose levels if you have diabetes. There are a variety of vegetarian diets but all restrict animal meat. The vegan diet avoids animal products of any sort, including milk and eggs.
When properly planned using foods from all the food groups, vegetarian and vegan diets meet the requirements of the dietary guidelines. Those following vegan diets have to take extra care that they get adequate vitamin D, calcium, vitamin B12, iodine and iron. Vitamin B12 does not exist in the plant world and has to be obtained either through supplements or fortified cereal and soy products.
Vegan diets are low in saturated fat, cholesterol and high in fiber, which make them ideal diets for reducing the risk of heart disease. People with diabetes are at increased risk of heart disease and stroke so diets that can improve heart health are a bonus. Vegetarian diets can be heart healthy or not depending on the amount of regular dairy products (whole milk, yogurts, cheeses) that are consumed.
Vegetarian diets depend on a mixture of plant and animal sources to meet protein needs. Plant proteins are the only available proteins in the vegan diet. This makes these diets, particularly the vegan diet, heavily carbohydrate-based. Carbohydrates are the nutrients that have the most effect on blood glucose control. However, both amount and source of carbohydrate determine the degree and the rate of glucose rise after meals. Similar to omnivore diets, those vegetarian and vegan diets that contain more whole grains vs. processed grains and whole fruits rather than juices cause fewer glucose spikes.
Some studies have shown that vegan diets can be beneficial in helping people with type 2 diabetes lose weight and keep their glucose levels in control. Since well-planned vegan diets tend to be very high in fiber, they help keep people satisfied after meals which decreases extra calorie intake. In addition, very high levels of fiber do have a glucose lowering effect.
Making sure that carbohydrates are divided up through the day, rather than eaten all at one time, and are combined with a source of protein and or healthful fat is a good way to reduce the impact of higher overall carbohydrate load on metabolic control. For example, a dinner of brown rice stir-fried with tofu and broccoli in canola oil and a serving of berries with imitation whip cream for dessert would follow the guidelines of the plate method of carbohydrate control.
The evidence for vegan diets being either superior or inferior to those diets containing animal products for the treatment of type 1 diabetes is sparse. However, larger carbohydrate loads when derived from non-starchy vegetables and beans should have a smaller effect on glucose excursions than similar servings of white rice and potatoes. Of course, engaging in exercise on a regular basis will help you metabolize the extra carbohydrate more efficiently.