Effect of tight control of HbA1c and blood pressure on cardiovascular diseases in type 2 diabetes: an observational study from the Swedish National Diabetes Register (NDR).

AIM: To estimate hazard ratio (HR) of first incident fatal/non-fatal cardiovascular diseases (CVD) in female/male type 2 diabetic patients, with tight versus adverse control of HbA1c and blood pressure (BP) at baseline, age 30-70 years, no baseline CVD, followed for mean 5.7 years.
METHODS: 2593 patients with tight control of HbA1c <7.5% and BP < or = 140/90 mmHg (median 6.5%/130/80 mmHg), and 2160 patients with adverse control 7.5-9.0%/141-190/91-110 mmHg (median 8.1%/155/85 mmHg).
RESULTS: The hazard ratio (HR) for CVD with tight/adverse control was 0.67 (0.55-0.80; p<0.001), adjusting for age, sex, duration, hypoglycaemic treatment, smoking, BMI, lipid-lowering drugs, antihypertensive drugs, microalbuminuria. Adjusted HR for myocardial infarction, coronary heart disease, stroke and total mortality were 0.72 (0.56-0.92; p=0.01), 0.69 (0.55-0.86; p<0.001), 0.62 (0.45-0.84; p<0.001), 1.00 (0.72-1.39). The partial population-attributable risk percent for myocardial infarction, stroke and CVD was 23%, 33%, 29% if adverse HbA1c/BP control could be avoided, while 43%, 38%, 39% with overweight and smoking also avoided. Baseline lower BMI and absence of microalbuminuria were associated with tight control.
CONCLUSION: Median difference of HbA1c/BP 1.6%/25/5 mmHg between tight and adverse control considerably reduced the risk of cardiovascular diseases. The findings call for a multi-factorial approach to improve HbA1c, BP, obesity, smoking, and microalbuminuria.