Hypertension in diabetes mellitus

Abstract

Recent US National Health and Nutritional Examination Surveys of adults have estimated the age-adjusted prevalence of diabetes and hypertension at 8.3 % and 29 %, respectively. However, the prevalence of both conditions increases nearly exponentially with age and body-mass index, such that 67 % of diabetics had blood pressures =140/90 mmHg (or were taking antihypertensive medication) in the 2005-2008 datasets. Data from epidemiological studies and clinical trials in hypertensive subjects indicate that diabetes roughly doubles the risk of cardiovascular disease. For the US national dataset gathered from 2005 to 2010, diabetes and hypertension increased the risk for chronic kidney disease by a factor of 3.4 and 2.4, respectively. Across the USA, either diabetes or hypertension was cited in 2010 as the primary reason for end-stage renal disease in 44 % or 28 %, respectively, of those requiring renal replacement therapy. Clinical trials comparing antihypertensive therapy vs. placebo/no treatment in diabetics have demonstrated significant reductions in both cardiovascular and renal endpoints; the data are particularly strong for a single inhibitor (but not multiple inhibitors) of the renin-angiotensin system. Some, but not all, clinical trials have shown benefit for a lower-than-usual blood pressure target for diabetics, so current US guidelines suggest a blood pressure of <140/80 mmHg, and perhaps even lower for diabetics with proteinuria >1 g/day. It is abundantly clear that hypertension increases the risk of all cardiovascular and renal endpoints in diabetes, and that one or more type of antihypertensive drug therapy decreases these risks. What is not clear is whether, in all diabetics, the additional effort required to reduce blood pressure to a lower-than-usual target results in better outcomes, either clinically or economically.