Hypertension and Diabetes

Summary

The choice of an appropriate antihypertensive agent and the hazards of postural hypotension are common problems faced in the treatment of diabetic hypertensive patients. The results of 3 studies addressing these problems are described in this report. In the first study, indoramin, an α-blocking agent, was administered to patients with non-insulin-dependent diabetes and mild to moderate hypertension. Blood pressure control was achieved in 57% of patients with mild, and in none with moderate hypertension. The blood glucose and insulin responses to an oral 50g glucose loading, as well as the blood concentrations of HbA₁ did not change during therapy. Seven patients were excluded because of side effects. In 4 of them postural hypotension was observed.

In the second study, the effects of angiotensin-converting enzyme (ACE) inhibitors, administered to patients with non-insulin-dependent diabetes and mild to moderate hypertension, were evaluated. Blood pressure control was achieved in 78% of the patients on captopril ( n=14 ) and in 74% of patients on enalapril therapy ( n=23). Symptomatic postural hypotension (n=2) and hyperkalaemia n=2 were observed with both drugs. Significant reductions in 24-hour urinary protein or albumin excretion were detected in 12 patients on enalapril therapy. No changes in 2-hour postprandial blood glucose and HbA₁ levels were observed during therapy with ACE inhibitors. In the third study, dopaminergic antagonist agents were evaluated in diabetic patients with orthostatic hypotension. In 7 patients metoclopramide (20mg intravenously) reduced the fall in mean arterial pressure induced by upright tilt. This response was associated with increases in total peripheral resistance and no changes in cardiac output. In addition, domperidone, a peripheral dopaminergic antagonist, was given to 9 diabetic patients with orthostatic hypotension. Marked increases in upright systolic and diastolic blood pressure were detected after a period ranging from 10 to 30 days, and maintained in 6 patients who completed 1 year of therapy.

Our results indicate that α-blockers may be a good therapeutic option for diabetic patients with mild hypertension. ACE inhibitiors are effective antihypertensive agents in diabetic patients but should be used with caution in those with renal failure or autonomic neuropathy. Dopaminergic antagonists appear to be effective in the treatment of diabetic orthostatic hypotension.