Definition:
Insulin resistance is the condition in which normal amounts of insulin are inadequate to produce a normal insulin response from fat, muscle and liver cells. There is decreased sensitivity of target cells (muscle, adipose and hepatic cells) to insulin.
Normally insulin is released from pancreatic beta cells after eating. The insulin signals the body to allow glucose to enter insulin-sensitive tissues (e.g., muscles, adipose tissue) and maintain normal blood glucose levels. In an insulin resistant
person the message does not get through, and more and more insulin is released in an attempt to compensate. Occasionally, this can lead to a steep drop in blood sugar and a hypoglycaemic reaction several hours after the meal. As the disorder progresses, hyperglycaemia develops as pancreatic beta cells are unable to produce adequate insulin to maintain
normal blood sugar levels. The inability of the beta cells to produce more insulin in the condition of hyperinsulinaemia is what characterises the transition from insulin resistance to type 2 diabetes.
Insulin resistance in fat cells results in hydrolysis of stored triglycerides, which elevates free fatty acids in the blood plasma. Insulin resistance in muscle reduces glucose uptake, whereas insulin resistance in liver reduces glucose storage, with both effects serving to elevate blood glucose. High plasma levels of insulin and glucose due to insulin resistance often leads to Metabolic Syndrome, increased risk of cardiovascular disease and type 2 diabetes.

Risk factors:
Factors that can contribute to the incidence of insulin resistance include:
• Obesity
• Physically inactive
• Low fat, high carbohydrate and/or high calorie diets
• Stress
• Systemic acidosis
• Family history of diabetes and/or insulin resistance
• Haemochromatosis
• Polycystic ovarian syndrome (PCOS)
• Hypercortisolaemia (e.g., steroid use or Cushing's disease)
• Drugs (e.g., glucocorticoids, progestrogens, many antiretrovirals, possibly alcohol)
• Low HDL cholesterol, high LDL and/or high triglycerides
• High blood pressure
• History of gestational diabetes
• Hormonal imbalances (e.g., hypercortisolaemia)
• Systemic toxicity
• Inflammatory disorders

Signs and Symptoms:
Common signs and symptoms of insulin resistance include the following:
• Blood glucose dysregulation
• Acanthosis nigricans (a brown to black, poorly defined, velvety hyperpigmentation of the skin)
• Increased visceral adiposity–particularly truncal obesity with waist circumference >80cm in women and >94cm in men
• Cardiovascular disease–i.e., hypertension, dyslipidaemia, hypercoagulable states
• Increased inflammatory cytokine levels
• Polyuria and/or polydipsia
• Fatigue
• Blurred vision
• Increased incidence of thrush
• Fungal infections of the skin
• Reduced immunological resistance to infection
• Nervous system disturbances–e.g., decreased concentration, diminished memory, impaired task performance, headaches, irritability.