According to the International Diabetes Federation, South Africa ranks amongst the top five countries with the highest diabetes incidence in Africa, with an age-adjusted (20–79 years) comparative incidence of 10.8%.1 Diabetes mellitus is a metabolic condition characterised by elevated blood sugar levels (hyperglycaemia) and metabolic disturbances of carbohydrates, fat and protein, which result from defects in insulin secretion, action or both.2 This evidence concerns the gene INS and diabetes mellitus.