Diabetes and its complications are fast becoming the UK’s No. 1 health threat, outstripping smoking-related diseases, cancer and drugs. Type 2 or so-called ‘adult’ diabetes, is by far the commonest form of diabetes. It’s hugely on the increase – teenagers and even some children are now getting it. We need to find out why.
Why is type 2 diabetes a problem?
Type 2 diabetes is more serious than people think because of its complications. It is the commonest cause of blindness, kidney failure and amputation. Heart attacks and strokes are three times more likely in type 2 diabetes.
When does type 2 diabetes start?
The seeds of type 2 diabetes are probably sown in early childhood, long before the symptoms become obvious. In some, the fuse that leads to diabetes will burn very slowly; in others, it will burn more rapidly and we need to know how to put it out before diabetes develops. Crucially, we need to know what ignites the fuse in the first place.
Why the intense interest now?
Only recently has it become clear that diabetes is not a single disorder but part of a much broader metabolic syndrome. In the past, large vessel (macrovascular) disease, heart attacks and stroke were looked upon as complications of diabetes. Now we recognise them all as outcomes of a single disturbance – insulin resistance. Insulin resistance results largely from lifestyle factors involving overnutrition and underactivity. Their most obvious expression is obesity, and upper body (intra-abdominal) obesity in particular seems to be associated with insulin resistance. As the tissues become less sensitive to insulin, the blood glucose rises and stimulates the pancreatic beta cells to make more insulin. The result, crucially, is hyperinsulinaemia, and the high levels of insulin drive disturbances as diverse as coronary heart disease in middle age and infertility in young women. It may be many years, even decades, before diabetes develops. Indeed, diabetes may never occur if the beta cells can match every rise in insulin resistance with a corresponding increase in insulin production. It will be clear, however, that each increment in insulin level will be associated with a rise in coronary risk. Many are beginning to look on diabetes as primarily a cardiovascular disease, hence the particular focus on understanding and preventing it. At present there is only very limited evidence on how early in childhood insulin resistance emerges, what causes it and how to prevent it progressing.
What is the difference between type 1 and type 2 diabetes?
Some will argue that there is no difference, and that insulin resistance underlies both. Certainly, with what used to be called ‘maturity-onset’ diabetes occurring in childhood and ‘childhood’ diabetes presenting in adulthood, it can sometimes be difficult to make a distinction. Type 1, by definition, is insulin requiring, while type 2 is not. The type 2 diabetic whose insulin needs, as a result of insulin resistance, ultimately exceed the capacity of his beta cells to make sufficient insulin will become an insulin-requiring type 1. There is a prevailing view among many diabetics that type 2 is the mild form, and type 1 the severe form of diabetes. Nothing could be further from the truth. The high insulin levels in type 2 diabetes kill relentlessly by premature heart disease. Of course, the childhood diabetic who puts on excessive weight later on will need increasing doses of injected insulin to overcome his weight-induced insulin resistance.
Insulin resistance is a fundamental and inescapable problem for diabetes, and the primary aim of management – whether type 1 or type 2 – should be achievement of ideal weight, and with it minimum insulin levels.
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