What is type 2 diabetes?

Type 2 diabetes is the most common variety of diabetes. It is a disorder of carbohydrate metabolism in which the body effectively becomes resistant to the hormone insulin. Initially, the person with this disorder has impaired tolerance to glucose. This develops into high blood glucose levels after eating and eventually high blood glucose levels even when fasting.

However, some people with type 2 diabetes remain relatively sensitive to insulin, while others have little or no insulin sensitivity. This difference affects treatment of the disease. In general, those type 2 diabetics who are not obese retain some sensitivity to insulin.

The causes of type 2 diabetes are complex. Insulin resistance is the main metabolic abnormality leading to the development of type 2 diabetes. The most recent research suggests that type 2 diabetes can be seen as a consequence of a series of physiological disruptions, each of which makes the person vulnerable to subsequent disruption of normal glucose metabolism.

Insulin resistance is common and is usually caused by obesity. There are effectively three stages in the development of type 2 diabetes:

• Insulin resistance, for which the body compensates by increasing the secretion of insulin to allow the liver and muscles to continue to function normally.
• Eventually the pancreas is unable to produce enough insulin to compensate for the insulin resistance. This leads to a sequence of impaired glucose tolerance, high blood glucose after eating (postprandial hyperglycaemia) and finally, high blood glucose levels even when fasting (fasting hyperglycaemia) and worsening postprandially. These high glucose levels are toxic not only to the large and small blood vessels but also to the cells producing insulin, the so-called beta-cells of the pancreas.
• This damage to the beta-cells leads to a decline in their function and eventually less insulin is produced as the disease progresses.

The raised fasting and postprandial glucose levels result in complications that affect the small and large blood vessels of the body. This contributes to renal failure, eye complications and, more importantly, accelerated atherosclerosis leading to strokes and heart disease. The artherosclerotic complications are responsible for 80% of the deaths in diabetics.

Type 2 diabetes in Australia
Worldwide, the percentage of people with diabetes is highly variable among geographical regions and populations, so estimates are often inaccurate.

However, according to Diabetes Australia, an estimated 280 Australians develop diabetes every day. The 2005 Australian AusDiab Follow-up Study showed that 1.7 million Australians have diabetes, but that up to 50% of people with type 2 diabetes remain undiagnosed. What’s more, up to 60% of cases of type 2 diabetes can be prevented.

The risk factors for type 2 diabetes are:

• Obesity
• Lack of exercise
• An abnormal lipid profile
• A family history of the disease

A typical person at risk for type 2 diabetes would be:

• Overweight
• Excessive thirst
• Excessive urination
• Loss of weight

However, these are late signs that occur when the person is already seriously hyperglycaemic.

Early in the course of the disease there are more subtle signs such as fatigue, greater susceptibility to illness and poor wound healing.

A very common early sign in men is erectile dysfunction, as is candida infection of the tip of the penis (candida balanitis). In women, persistent vaginal candida may be an early sign of type 2 diabetes, particularly in older women.