Why do Aboriginal people experience higher rates of diabetes?

August 17th, 2010

In an aim to address the high rates of diabetes among Aboriginal people, the Government of Canada recently announced $110 million over two years for the Aboriginal Diabetes Initiative. Why do Aboriginal people experience higher rates of the condition? Dr. Bernard Zinman of the Department of Medicine at U of T and Mount Sinai Hospital, who specializes in diabetes and its long term complications reveals why, as well as who else might be at risk.

Why do Aboriginal people seem to experience a high frequency of Type 2 diabetes?

First let me explain that there are two types of diabetes – Type 1 and Type 2. Type 1 diabetes is the result of an autoimmune attack on the pancreas – specifically the beta cells of the pancreas that make insulin.

Type 2 is more complex. For Type 2, there’s both insulin resistance and a failure of beta cells to make sufficient insulin to overcome the resistance. Type 2 is the result of an interaction between environmental factors – such as nutrition, lack of exercise and obesity – and genetic factors, primarily the capacity of the pancreas to make more insulin to overcome the environmental factors and meet the body’s needs.

Aboriginal people in the past lived mostly hunter-gatherer lifestyles. They moved with the seasons and stayed very active while searching for food. Consequently, they developed a certain genotype that allowed them to effectively store energy during feasts, which helped them survive during times when food was scarce.

Their current nutritional circumstances have changed dramatically. Many Aboriginal people live on reserves. They do less hunting and fishing. There’s a high rate of unemployment and the foods that they’re exposed to are high in calories, fat and carbohydrates. As a result, there’s a high rate of obesity and the obesity leads to high rates of Type 2 diabetes.

It would also appear that for any given amount of obesity, they experience more diabetes than a matching Caucasian population with the same amount of obesity. In essence, Aboriginal people have genetic susceptibility for Type 2 diabetes. The rapid change in nutritional environment is what brought this out.

You mention that Type 2 is due to environmental factors and genetics. Do kids of parents who have Type 2 have a higher chance of being born with Type 1?

No. Children of parents who have Type 2 will have a high chance of ultimately developing Type 2 diabetes. Similarly children of parents who have Type 1 will have an increased risk of developing Type 1 diabetes.

The age of onset doesn’t completely define the type of diabetes a person can develop – even though historically Type 1 develops at a younger age and Type 2 in adulthood.

It’s important to note that Type 1 and Type 2 are two completely different diseases that just happen to share the same potential negative consequences of elevated blood sugar – namely an increased risk of blindness, heart diseases, kidney failure, lower limb amputation and the list goes on. It’s the uncontrolled high blood sugars that lead to these disabling complications.

Individuals suffering from Type 1 – more often than not – develop diabetes at a young age. Therefore, they’re exposed much earlier to high blood sugars and tend to encounter more serious complications. However, research studies have clearly demonstrated that if their diabetes is managed well, the risk of complication is dramatically reduced.

Is there also a high rate of Type 1 diabetes among Aboriginal people?

No, not at all. Although Type 1 diabetes does occur in Aboriginal people, the rate of this type is actually quite low.

What type of diabetes do you study?

We do research in both Type 1 and Type 2 diabetes. As an example, in Type 1 diabetes we’ve participated in a landmark study called The Diabetes Control Complications Trial (DCCT), which is probably the most important trial ever undertaken for Type 1. The ongoing trial includes 1,441 patients with Type 1 diabetes in the Unites States and Canada and established without any doubt that intensive glucose control with pumps or daily multiple injections of insulin coupled with close glucose monitoring dramatically reduces the long term complications of diabetes. The findings from this trial have become standard of care for all Type 1 diabetes patients in the world.

In another current study, we’re testing to see whether certain newer medications can improve glucose control and reduce cardiovascular disease at the same time. While testing these drugs, we’re also looking to see if it would be possible to put diabetes into remission early on in the condition.

Diabetes remission has been achieved by other researchers in the past. The problem, however, is that the remission is not sustained. In our study, we’ll induce diabetes remission using insulin for a brief period early in the course of Type 2 diabetes and then stop the insulin to see if we can sustain the remission with the new medications. If this hypothesis is correct our thinking about diabetes interventions may change completely.

My research is conducted at the Diabetes Centre, Samuel Lunenfeld Research Institute at Mount Sinai Hospital, which continues to be a clinical research leader for both Type 1 and Type 2. At this time we are looking for study participants who are in the early stages of Type 2 diabetes or are currently receiving medication for Type 2 diabetes. To obtain more information, interested candidates are encouraged to call 416-586-4800 ext. 4447.