Diabetes mellitus (DM) is a syndrome of chronic hyperglycaemia
due to relative insulin deficiency, resistance or both.Diabetes is usually irreversible and, although patients can lead a reasonably normal lifestyle, its late complications result in reduced life expectancy and major health costs.
These include macrovascular disease, leading to an increased prevalence of coronary artery disease, peripheral vascular disease and stroke, and microvascular damage causing diabetic retinopathy and nephropathy. Neuropathy is another major complication.
Primary diabetes is classified into:
How do you get diabetes?
Type 2 diabetes mellitus which was previously referred to as non-insulin-dependent diabetes mellitus (NIDDM) is the predominant form worldwide, accounting for 90% of patients with DM. Tissue insensitivity to insulin action (i.e. insulin resistance), and an inability of the pancreatic b-cells to compensate adequately for this, leads to overproduction of glucose by the liver and under utilisation by other tissues, with an inevitable rise in blood glucose levels – i.e. there is relative insulin deficiency.
Typically, in Type 2 Diabetes Mellitus (DM) there is a positive family history. In most affected individuals the inherited component is likely to be polygenic, involving interaction between multiple genes involved in both insulin secretion and insulin action. Overall, the risk of a sibling or offspring of a person with type 2DM developing the condition is high (as much as 33%; identical twins are affected in 60–100% of cases).
Type 2 DM, is strongly linked to obesity, which predisposes to insulin resistance. So any daily activity which make you obese will lead to diabetes after many years.
The overweight or obese should be encouraged to lose weight by a combination of changes in food intake and physical activity.
CLINICAL PRESENTATION OF DIABETES
Presentation may be acute, subacute or asymptomatic.
Young people often present with a 2–6-week history and report the classic triad of symptoms:
The clinical onset may be over several months or years, particularly in older patients. Thirst, polyuria and weight loss are typically present but patients may complain of such symptoms as lack of energy, visual blurring (owing to glucose-induced changes in refraction) or pruritus vulvae or balanitis that is due to Candida infection.
Complications as the presenting feature
Glycosuria or a raised blood glucose may be detected on routine examination (e.g. for insurance purposes) in individuals who have no symptoms of ill-health. Glycosuria is not diagnostic of diabetes but indicates the need for further investigations. About 1% of the population have renal glycosuria. This is an inherited low renal threshold for glucose, transmitted either as a Mendelian dominant or recessive trait.