Association of glycaemia with macrovascular and microvascular complications of type 2 diabetes (UKPDS 35): prospective observational study

Objective To determine the relation between exposure to glycaemia over time and the risk of macro vascular or microvascular complications in patients with type 2 diabetes. Design Prospective observational study. Setting 23 hospital based clinics in England, Scotland, and Northern irelan d. Participants 4585 white, Asian Indian, and Afro-Caribbean UKPDS patients, w hether randomised or not to treatment, were included in analyses of inciden ce; of these, 3642 were included in analyses of relative risk. Outcome measures Primary predefined aggregate clinical outcomes: any end po int or deaths related to diabetes and all cause mortality. Secondary aggreg ate outcomes: myocardial infarction, stroke, amputation (including death fr om peripheral vascular disease), and microvascular disease (predominantly r etinal photocoagulation). Single end points: non-fatal heart failure and ca taract extraction. Risk reduction associated with a 1% reduction in updated mean HbA(1c) adjusted for possible confounders at diagnosis of diabetes. Results The incidence of clinical complications was significantly associate d with glycaemia. Each 1% reduction in updated mean HbA(1c) was associated with reductions in risk of 21% for any end point related to diabetes (95% c onfidence interval 17% to 24%, P < 0.0001), 21% for deaths related to diabe tes (15% to 27%, P < 0.0001), 14% for myocardial infarction (8% to 21%, P< 0.0001), and 37% for microvascular complications (33% to 41%, P < 0.0001). No threshold of risk was observed for any end point Conclusions Ln patients with type 2 diabetes the risk of diabetic complicat ions was strongly associated with previous hyperglycaemia. Any reduction in HbA(1c) is likely to reduce the risk of complications, with the lowest ris k being in those with HbA(1c) values in the normal range (< 6.0%).