14.01.1 Diabetes Mellitus

Diabetes means large volume of urine flowing through. Diabetes mellitus is when the urine is sweet. Diabetes insipidus is when the urine is tasteless. Diabetes insipidus is a rare condition due to impaired renal conservation of water. Diabetes mellitus is the subject of this chapter.

One million Australians have diabetes mellitus, including 20% of those over 65. Diabetes is an enormous burden to the economy, as 10-15% of total health expenditure is on diabetes, of which 6% is on diabetes medications and the rest is spent on diabetic complications. In diabetes the underlying syndromes is hyperglycemia, high circulating levels of glucose. The glucose sticks to many sites to interfere with many processes in the body, and this underlies the complications with diabetes. The glucose sticks to haemoglobin, and we use this to monitor the ongoing glucose levels in diabetes. Thus, glycosylated haemoglobin is used as a measure of diabetes mellitus, and effective treatments lower the percentage of glycosylated haemoglobin. By sticking to things, hyperglycemia is associated with the altered metabolism of lipids, carbohydrates and proteins.

There are two types of diabetes mellitus. Type I diabetes mellitus (which was previously known as insulin-dependent diabetes mellitus (IDDM)) only accounts for 10% of diabetes. Type I diabetes is a juvenile onset, autoimmune disease of the pancreatic cells that secrete insulin. Once the pancreatic cells are destroyed the individual no longer produces or stores insulin. As insulin is essential to the management of glucose in the body, the resulting high levels of glucose can have major effects, if left untreated.

Type 2 diabetes mellitus (previously known as non-insulin dependent diabetes mellitus (NIDDM) or maturity onset diabetes) is the common one, and the type of diabetes that is epidemic in the Westernized world. Type 2 diabetes, which accounts for 90% of the diabetes mellitus, is more common in adults but can occur in children or adolescents if they are overweight or obese. Type 2 diabetes is characterized by low levels of insulin and/or loss of insulin sensitivity. Type 2 diabetes is caused by a variety of genetic and environmental factors. These are multifactorial (involve many factors), heterogenous (vary between people), and include obesity, ethnicity, hypertension, and hyperlipidemia.

Diabetes leads to many complications with nearly 60% of diabetic deaths being cardiovascular, predominantly myocardial infarction and stroke. Diabetes also causes damage to the kidney and diabetic kidney disease is the most common cause of end-stage renal failure. Diabetes used to also cause a lot of blindness and neuropathy. Today, if diabetes is managed well, these conditions are slow to develop.