Trends in antihypertensive and lipid-lowering therapy in subjects with type II diabetes: clinical effectiveness or clinical discretion?

Hypertension and lipid disorders in type II diabetes contribute to increased coronary risk, but optimal drug therapy has not been defined. We investigated primary care physicians choices of antihypertensive and lipid-lowering therapy for subjects with type II diabetes diagnosed with hypertension. Subjects were registered with 105 UK general practices in the General Practice Research Database and prescribed oral hypoglycaemic drugs for the first time between January 1993 and December 2001. We evaluated prescriptions for antihypertensive drugs in subjects with secondary diagnoses of hypertension in the first year following initiation of oral hypoglycaemic therapy. Data were analysed for 4519 diabetic subjects with diagnosed hypertension. Between 1993 and 2001, the proportion prescribed thiazide diuretics increased from 20 to 30%; angiotensin-converting enzyme (ACE) inhibitors from 35 to 45% and angiotensin receptor blockers from 0 to 8%. The proportion of subjects prescribed lipid-lowering therapy increased from 8% in 1993 to 33% in 2001, with the proportion prescribed statins increasing from 1 to 30%. At different general practices, the proportion prescribed thiazide diuretics ranged from 0 to 52%, beta-blockers from 5 to 60%, ACE inhibitors from 15 to 81%, and statins from 0 to 50%. Variation between practices was not explained by adjusting for age, sex, prevalent coronary heart disease or study year. Trends in drug utilisation were consistent with the evolving evidence base but there were wide variations in drug utilisation between practices. A more consistent approach to drug selection might be associated with improved patient outcomes.