Definition, epidemiology, diagnosis and classification

Diagnosis

• In the majority of young people the diagnosis of type 1 diabetes should be made without difficulty and with urgency
• The symptoms of thirst, excessive drinking and urination should prompt immediate confirmatory tests for
  • heavy glycosuria (>55 mmol/l; 1.0 g/dl)
  • possible ketonuria (often >4 mmol/l; 0.4 g/l acetoacetate)
  • random hyperglycemia (BG 11.1 mmol/l; 200 mg/dl)

• In some countries and in certain circumstances diabetes may be of slower onset and present diagnostic difficulties
• In contrast, some forms of type 2 diabetes present acutely with ketoacidosis
• If the diagnosis of diabetes is uncertain the following investigations may help

1. Repeated random tests for BG, glycosuria and HbA_1c
2. Measurement of islet cell autoantibody markers, e.g. ICA, GAD, IA2 and IAA
3. Review of risk factors
   • family history of type 1 or type 2 diabetes
   • obesity (type 2)
   • autosomal dominant history suggesting genetic defects of beta-cell function
4. Oral glucose tolerance test (OGTT)
   • in fasting state (but only after previously normal carbohydrate intake)
   • glucose orally 1.75 g/kg body weight (maximum 75 g)