By: Thomas Pickering, MD, DPhil, FRCP, Director of Integrative and Behavioral Cardiology Program
of the Cardiovascular Institute at Mount Sinai School of Medicine, New York.

People who have diabetes often have hypertension as well and are at increased risk of heart disease. Other major complications of diabetes include damage to the kidneys (nephropathy), eyes (retinopathy), and nerves (neuropathy). Research has suggested that complications will be less likely to develop if the blood pressure is lowered very aggressively. For patients whose diabetes comes on at a young age, and who require insulin for its treatment, there is evidence that ACE inhibitors are better at preventing some of the complications than other antihypertensive drugs. It is uncertain whether the same applies to patients with non-insulin-dependent diabetes, which typically starts in middle age.

The ABCD (Appropriate Blood Pressure Control in Diabetes) trial was designed to find out whether lowering the diastolic pressure to 75 mm Hg or less would be better at preventing the progression of the complications described above than keeping the pressure at 80 to 89 mm Hg. A secondary goal was to find out whether a long-acting calcium channel blocker (Sular, or nisoldipine) would be as good as an ACE inhibiotr (Vasotec, enalapril) in delaying the complications.

All patients in the trial had non-insulin-dependent diabetes and were aged between 40 and 74 years. This report analyzed the results in the 470 patients who were also hypertensive, of whom half were treated with nisoldipine and half with enalapril. The main finding was that the rate of heart attacks over five years was significantly lower in the patients treated with enalapril (five heart attacks) than in those given nisoldipine (22 heart attacks).

Doctor's comments

The finding that ACE inhibitor treatment results in fewer heart attacks than treatment with calcium channel blockers in patients with non-insulin-dependent diabetes was unexpected. It raises a big question: do ACE inhibitors protect against heart attack, or do calcium channel blockers provoke it? Because there was no group given other blood pressure-lowering drugs or placebo, this study does not give an answer. You should not conclude from this study that calcium channel blockers are dangerous, but rather that if you have diabetes, an ACE inhibitor is preferable. This is also the recommendation of the Joint National Committee.

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