An Overview of Diabetes and its Complications

Abstract

Diabetes mellitus is a metabolic disorder in which the body’s capacity to utilise glucose, fat and protein is disturbed due to impairment in insulin secretion and/or insulin resistance leading to chronic hyperglycaemia. Therefore, having an understanding of the underlying pathophysiology and the acute and/or long-term complications of diabetes will enable the development of strategies for ameliorating the condition. Individuals may be classified as having pre-diabetes or diabetes based on their fasting blood glucose and/or postprandial blood glucose. In this regard, individuals with impaired fasting glycaemia (IFG) have fasting plasma glucose >6.1 mmol/L to 7.8 mmol/L to <11.1 mmol/L following a 2 hour oral glucose tolerance test and both IFG and IGT define the extent of glucose dysregulation between the range of normoglycaemia and type 2 diabetes. The diagnostic criteria for patients with diabetes are fasting plasma glucose ≥7.0 mmol/L and oral glucose tolerance Test (OGTT) ≥11.1 mmols/L.1 While normal fasting glucose depends on the ability to sustain the production of basal insulin and promotion of insulin sensitivity at the level of the liver, IFG results from abnormalities of these metabolic functions and are often characterised by raised hepatic glucose output and defect in early insulin secretion.2 However, during OGTT, the normal body’s response is usually in the form of increased insulin secretion, decreased hepatic glucose production and enhanced glucose uptake in the liver and the muscle. Therefore, IGT is often associated with peripheral insulin resistance, mostly in the skeletal muscle. In addition to IFG and IGT, other risk factors for type 2 diabetes include genetics/family history, environmental factors such as type of diet and physical activity, obesity, age and body fat distribution.