Is New-Onset Diabetes Mellitus Important?

Abstract

Diabetes mellitus is a powerful risk factor for cardiovascular disease (CVD), and most persons with diabetes ultimately succumb to coronary artery disease or stroke. The coincidence of hypertension and diabetes is common and, over the long term, sharply increases cardiovascular risk. The incidence of diabetes (new-onset diabetes [NOD]) among hypertensive persons is high, and appears to be increased during antihypertensive therapy. NOD is a distressing clinical event, provoking psychological distress, more clinical testing, and, sometimes, the need for hypoglycaemic therapy. Diuretics and β-blockers are more likely to provoke NOD than other drugs that block the renin angiotensin system, or calcium channel blocking agents, It is important to note that the alternative agents have not been shown to prevent the emergence of hyperglycaemia, but seem to be metabolically neutral. It is also true that because diuretic-induced NOD may be due to hypokalaemia, it can sometimes be reversed without sacrificing diuretic therapy. The evidence suggests that most NOD appearing during antihypertensive therapy is not drug induced, but rather part of the natural history of disease. Since diabetes is such a powerful CVD risk factor, it can hardly be surprising that, over the long term, NOD is associated with increased CVD. However, there is no evidence in short-term clinical trials that diuretic-induced NOD increases CVD or detracts from the cardioprotective effects of these agents. Indeed, long-term follow-up of participants in a large placebo-controlled trial of diuretic therapy in elderly hypertensive subjects suggests that this antihypertensive therapy actually eliminates the expected increase in CVD. In summary, although NOD can hardly be dismissed as a trivial event, concern about its possible occurrence is not a reason to influence initial antihypertensive drug selection, nor does its appearance provide a reason to compromise antihypertensive therapy. Indeed, the available evidence suggests that blood pressure control trumps hypoglycaemic therapy as the very best tool for CVD prevention in new or established diabetic subjects.