Carbohydrate restriction

Most doctors and many people with diabetes think that diabetes is mainly managed by changes in insulin doses or tablets. Diabetes may indeed be controlled with tablets or with insulin but diet is absolutely fundamental in long term wellbeing as well as in glucose control. Many people with diabetes can achieve excellent control by dietary means alone.

In the early days diabetes was seen as all about sugar - simply a disease of blood glucose and so a low carbohydrate diet was the obvious and standard advice. We now know that diabetes is far more complicated than this, and the treatments are designed not just to keep blood sugar levels down, but to prevent the complications that occur over the years. We have to take in our calories in some form and if we reduce carbohydrate we must increase protein or fat. Even lean meat, rich in protein, contains quite a lot of fat. People with diabetes are at increased risk of heart disease and it has been accepted for many years, despite a lot of evidence to the contrary, that a high fat diet is bad for heart disease. Therefore the advice from organisations such as the American Diabetes Association and Diabetes UK has been to use a diet low in fat and rich in “complex” carbohydrates.
 
Complex carbohydrates are said to have a low glycaemic index because they release glucose slowly. Sugars have a high glycaemic index as they release glucose fast. Even foods with a low glycaemic index are likely to lead to a significant rise in blood glucose levels, although the rise will be smaller than with those having a high glycaemic index. High peaks of blood glucose should be avoided. They seem to be toxic to cells and may be responsible for causing many of the complications of diabetes including coronary artery disease.
 
The whole question of the supposed dangers of fats in the diet is beginning to be looked at again, and the pendulum is swinging back towards cutting the amount of carbohydrate in the diet. Average blood glucose levels are reflected in the concentration of glycosylated haemoglobin (HbA1C) in the blood. Lower levels are associated with fewer complications in both Type 1 and Type 2 diabetes. But some people think that it is the fluctuations in the levels which matter just as much as the averages. It is not yet clear whether the source of the problem is fluctuations in glucose or insulin levels – both may be involved.

Low carbohydrate diets are at least as effective for weight loss as low-fat diets. Weight loss is important for those who are overweight as it reduces resistance to insulin. Substituting fat for carbohydrate has been shown in many studies to be beneficial in terms of weight loss and in reducing the risk of heart disease. Weight loss itself leads to better control in diabetes, but the benefits of a low carbohydrate diet are greater than those just connected with weight loss and are also seen in people with diabetes who are not overweight.

For many doctors, low carbohydrate diets are still controversial but the evidence supporting this approach is growing. Some people have reported “cures” for diabetes using very low carbohydrate diets, but these diets tend to be unpalatable and few can tolerate them. It may be that weight loss and improved blood tests might be due to the combination of an increased protein intake together with restriction of carbohydrate, but this is not yet clear. Higher protein intakes reduce glucose production from the liver and minimizes the excessive secretion of insulin, and people on diets higher in protein or fat eat less because these lead to a greater feeling of fullness and satisfaction.

As the advantages of lower carbohydrate intakes in diabetes are becoming increasingly accepted, the major associations and doctors’ organisations are beginning to change their recommendations, but the rate of change is slow, and people with diabetes are starting to take matters into their own hands.

Dr Tony Woolfson MB BS DM MRCP(UK)
Learn how to master your diabetes.  Visit my website at www.diabetesdietdoctor.com.