Diabetes - Type 2
Definition
Type 2 diabetes mellitus was once called adult-onset diabetes, typically affecting individuals older than 40 years. Now, because the epidemic of obesity and inactivity in children, type 2 diabetes is occurring at younger and younger ages: it has been diagnosed in children as young as 2 years of age who have a family history of diabetes.
Type 2 diabetes is characterised by peripheral insulin resistance with an insulin-secretory defect that varies in severity. For type 2 diabetes to develop, both defects must exist: All overweight individuals have insulin resistance, but only those with an inability to increase beta-cell production of insulin develop diabetes. In the progression from normal glucose tolerance to abnormal glucose tolerance, postprandial glucose levels first increase. Eventually, hepatic gluconeogenesis increases, resulting in fasting hyperglycaemia.
About 90% of patients who develop type 2 diabetes are obese. Because patients with type 2 diabetes retain the ability to secrete some endogenous insulin, those who are taking insulin do not develop diabetic ketoacidosis (DKA) if they stop taking it for some reason. Therefore, they are considered to require insulin but not to depend on insulin. Moreover, patients with type 2 diabetes often do not need treatment with oral antidiabetic medication or insulin if they lose weight.
Aetiology / Risk Factors
- Family history of type 2 diabetes—having a first-degree relative with type 2 diabetes leads to lifetime risk of 40%; similarly 25% to 33% of all type 2 diabetics have a family history of the condition
Age older than 40 years
Excess body fat, particularly truncal obesity with waist circumference >88 cm in women and >102 cm in men
Sedentary lifestyle with diet high in fats and calories
Glucose intolerance, dyslipidaemia, hypertension
History of gestational diabetes or polycystic ovary syndrome
Aboriginal or Torres Strait Islander, Pacific Islander, Indian or Chinese, African American, Hispanic American, and Native American.
Low birth weight and/or malnutrition in pregnancy may cause metabolic abnormalities in a foetus that later lead to diabetes.
Symptoms & Signs
Symptoms tend to appear gradually over a period of years, but once present may mimic some type 1 indicators. Type 2 diabetes is often asymptomatic (with elevated glucose found on routine exam), or an individual may present with:
Polyuria and polydipsia
Fatigue
Blurred vision
Vaginitis
Candidal infections of the skin
Poor vision
Pruritus
Impotence
Numbness or burning sensation of distal extremities
Frequent or recurrent urinary infections