Tuesday, December 2, 2008
Type 1 Diabetes
The pancreas is a multifunctional organ that sits below and behind the stomach. As an exocrine organ, it empties digestive enzymes into the gut at the level of the duodenum. The pancreas is also an endocrine organ, synthesizing insulin in its beta cells and glucagon in its alpha cells, and secreting those hormones into the blood.
Normally the pancreas performs its functions silently and efficiently. However in some cases the beta cells of the pancreas are vulnerable to an attack by the body's own immune system. For about three million Americans, the pancreatic beta cells are no longer functional, resulting in a condition called type 1 diabetes.
The cause of type 1 diabetes is not entirely clear. The peak age of diagnosis is 14 years, but type 1 diabetes can develop at any age. There is a genetic contribution--twenty percent of patients have a relative who also has the disease. The presence of other autoimmune disorders is a predisposing factor, and childhood viral infections such as rubella, cytomegalovirus and coxsackie B may trigger the condition. In any case, in these patients the body's immune system targets the beta cells of the pancreas and renders them unable to produce insulin.
Before Drs. Banting and Best discovered insulin in 1921, the diagnosis of type 1 diabetes was a death sentence. Victims had continuous thirst and voracious appetites, but without endogenous insulin to control their blood sugar, they wasted away because they could not properly utilize the food they ate. A very low carbohydrate diet could forestall the inevitable for several years, but most died before the age of 30.
With the advent of exogenous insulin therapy, a new set of problems arose for type 1 diabetics. Blood glucose could be controlled, but if it was poorly controlled, it would eventually result in eye, kidney and nerve diseases. If too much insulin was injected, it could result in severe hypoglycemia and even death. Dr. Richard K. Bernstein is a physician who developed type 1 diabetes in 1946 at the age of 12. He tells a fascinating story, showing how difficult it was in those days to match insulin dose to blood glucose level. The advent of the glucometer enabled patients to monitor their blood glucose much more accurately, but it also led to the temptation to eat large amounts of carbohydrates and then "cover" the carbs with injected insulin.
Today the American Diabetes Association recommends that diabetics eat 25-35% of calories from fat, 15-20% from protein and 45-55% from carbohydrates. By contrast, Dr. Bernstein proposes that eating a large number of calories as carbohydrates produces a large variability in blood glucose and a high level of difficulty in controlling blood sugar. To counteract this, he suggests something called the Laws of Small Numbers, which entails eating only small amounts of slow-acting carbohydrate, and no fast-acting carbohydrate at all.
Which approach is correct? No definitive scientific comparison is available, but this review notes that when the ACCORD study attempted tight glycemic control in type 2 diabetics through drug therapy, the study had to be terminated because of high mortality. By contrast, the reviewers cite a long list of references that indicate that dietary control of hyperglycemia is able to improve many of the long-term consequences of diabetes. Type 1 diabetics are unable to completely avoid the use of exogenous insulin, but the strategy of eating very small amounts of carbohydrate that require only small amounts of insulin, appears to be worth serious consideration.