The diet most often recommended for people who suffer from diabetes mellitus is high in dietary fiber, especially soluble fiber, but low in fat (especially saturated fat). Patients may be encouraged to reduce their intake of carbohydrates that have a high glycemic index (GI). However, in cases of hypoglycemia, they are advised to have food or drink that can raise blood glucose quickly, followed by a long-acting carbohydrate (such as rye bread) to prevent risk of further hypoglycemia.
Carbohydrates
The American Diabetes Association in 1994 recommended that 60-70% of caloric intake should be in the form of carbohydrates. This is somewhat controversial, with some researchers claiming that 40% is better, while others claim benefits for a high-fiber, 75% carbohydrate diet.
An article summarizing the view of the American Diabetes Association contains the statement "Sucrose-containing foods can be substituted for other carbohydrates in the meal plan or, if added to the meal plan, covered with insulin or other glucose-lowering medications. Care should be taken to avoid excess energy intake." Sucrose does not increase glycemia more than the same number of calories taken as starch. Although it is not recommended to use fructose as a sweetener, fruit should not be avoided because of its fructose content. Benefits may be obtained by consumption of dietary fibre in conjunction with carbohydrate; as Francis (1987) points out, evidence suggests that carbohydrate consumed with dietary fibre will have a less major impact on glycemic rise than the same amount of carbohydrate consumed alone.
What has not generally been included in diabetic diet recommendations is the variation in effect from different carbohydrates. Glucose is the only carbohydrate which participates in the primary metabolic control mechanism using insulin. That mechanism is ubiquitous amongst animals, from invertebrate nematode worms through the vertebrates, including humans.
Despite it is a common belief that table sugar contributes to the development of diabetes, it has medium (55-69) GI that actually lowers blood glucose levels than the equal amount of calories obtained from starch and other carbohydrates. The Canadian Diabetes Association recommended that table sugar be included as part of the diabetes diet.
In humans, some carbohydrates are not digested or absorbed—a prime example here is cellulose, which can be digested by ruminant animals and by termites (both using gut flora), but not by humans. In humans, cellulose and related carbohydrates are roughage, or dietary fibre, and pass through the human digestive system unchanged. Humans lack the enzymatic machinery needed to digest dietary multi-saccharides; we can handle only one or two di-saccharides and no larger ones except starch or glycogen. All other multi-saccharides which contribute to human nutrition will have been pre-processed by gut flora, with accompanying gas and other effects; the classic example is lactose, which most adult humans cannot digest—having lost lactase production after childhood—and the gastro-intestinal effects (eg, cramping, bloating, diarrhea) which sometimes follow for the lactose-intolerant. Indeed, only a few of the mono-saccharides can be absorbed by humans; most cannot. And of those, at least one, fructose, is somewhat problematic. It is metabolized only in the liver, and in men, in sperm, since only those tissues contain the fructase needed. The liver is affected by high levels of dietary fructose by characteristic unfavorable alterations in blood lipid profiles, and possibly in a connection to insulin resistance and so to Type 2 diabetes mellitus.
Low-carbohydrate alternatives
Some studies show low-carbohydrate diet and low GI diet may be effective in dietary management of type 2 diabetes, as both approaches prevent blood sugars from spiking after eating.
Dr. Richard K. Bernstein has a diet plan that is substantially different from the plan recommended here and he is harshly critical of the standard ADA diet plan for diabetics. His plan includes very limited carbohydrate intake (30 grams per day) along with frequent blood glucose monitoring, and regular strenuous muscle-building exercise, and for diabetics using insulin, frequent small insulin injections if needed. His treatment target is "near normal blood sugars" all the time.
Another critic of the ADA program is Ray Kurzweil, who together with Dr Terry Grossman, co-author of "Fantastic Voyage - Live long enough to live forever", (pub 2004) describes the ADA guidelines as "completely ineffective".Their observations are that the condition, particularly in its early stages can be controlled through a diet which has sharply reduced carbohydrate consumption. Their guidelines for patients with type 2 diabetes is a diet that includes a reduction of carbohydrates to one sixth of total caloric intake and elimination of high glycemic load carbohydrates. As a previously diagnosed diabetic who no longer has symptoms of the disease, Ray is a firm advocate of this approach.
Vegan and Raw/Live Foods alternatives
Recent studies have shown that a vegan diet may also be effective in managing type 2 diabetes. Raw food protocols for treating Type 2 diabetes can be found in Dr. Gabriel Cousens, MD's book "There Is a Cure For Diabetes" and the documentary he appears in with six diabetics and other doctors, "Simply Raw: Reversing Diabetes in 30 Days". Also of note are the writings of Victorian Boutenko whose son's diabetes disappeared after converting to a raw foods diet.
Timing of meals
For people with diabetes, healthy eating is not simply a matter of "what one eats", but also when one eats. The question of how long before a meal one should inject insulin is asked in Sonsken, Fox and Judd (1998). The answer is that it depends upon the type of insulin one takes and whether it is long, medium or quick-acting insulin. If patients check their blood glucose at bedtime and find that it is low, it is advisable that they take some long-acting carbohydrate before retiring to bed to prevent night-time hypoglycemia.
Alcohol and drugs
Moderation is advised with regards to consuming alcohol and the use of some drugs. Alcohol inhibits the glycogenesis in the liver and some drugs inhibit hunger symptoms. This, together with impaired judgement, memory and concentration caused by some drugs can lead to hypoglycemia.
Specific Diets
G.I. Diet - lowering the glycemic index of one's diet can improve the control of diabetes. This includes avoidance of such foods as potatoes cooked in certain ways, and white bread, and instead favoring multi-grain and sourdough breads, legumes and whole grains—foods that are converted more slowly to glucose in the bloodstream.
Low Carb Diet - It has been suggested that the gradual removal of carbohydrates from the diet and replacement with fatty foods such as nuts, seeds, meats, fish, oils, eggs, avocados, olives, and vegetables may help reverse diabetes. Fats would become the primary calorie source for the body, and complications due to insulin resistance would be minimized. However, it's vitally important that such a diet is low in saturated fats. The American Diabetes Association explains: "saturated fat raises blood cholesterol. High blood cholesterol is a risk factor for heart disease. People with diabetes have more frequent heart disease."
High fiber diet - It has been shown that a high fiber diet works better than the diet recommended by the American Diabetes Association in controlling diabetes, and may control blood sugar levels with the same efficacy as oral diabetes drugs.