Background and Objective: Little is known about the effects of the calcium channel antagonist manidipine when it is added as a third drug in non-controlled hypertensive patients with diabetes mellitus receiving dual anti-hypertensive therapy. The aim of this study was to evaluate the response in terms of blood pressure (BP) and microalbuminuria when manidipine is administered to patients with type 2 diabetes and uncontrolled hypertension who are already being treated with a combination of a low-dose diuretic plus an ACE inhibitor or an angiotensin II type 1 receptor antagonist (angiotensin receptor blocker [ARB]). We also evaluated the effects of addition of manidipine on plasma fasting glucose, glycosylated haemoglobin (HbA1c), serum uric acid, the lipid profile, serum creatinine and creatinine clearance.
Methods: This was a non-comparative, open-label study of hypertensive diabetic patients with systolic/diastolic BP >130/80 mmHg. All patients had been receiving treatment for ≥3 months with stable doses of a diuretic plus an ACE inhibitor or ARB. Manidipine 10 mg/day was added, increasing to 20 mg/day if the target BP was not reached after 3 months’ treatment. The follow-up period was 6 months. Patient compliance was verified by tablet count. The doses of statins being taken by patients prior to commencement of the trial were not modified during the study. All patients were treated with oral antihyperglycaemic agents only; patients receiving insulin were excluded from the study.
Results: 136 patients were enrolled in the trial and completed the study; 41.9% of the patients were males, the mean ± SD age of the study population was 64.4 ± 12.3 years, and the mean ± SD body mass index was 30.2 ± 4.9 kg/m2. The mean ± SD BP at baseline was 158.6 ± 15.6/86.7 ± 11.2 mmHg compared with 136.8 ± 12.0/78.0 ± 11.2 (−21.8/−8.7, respectively) mmHg at the end of the study period (p < 0.001). A total of 63.6% of the patients attained a BP of <140/90 mmHg and 20.9% attained a BP of <130/80 mmHg. The mean ± SD heart rate decreased from 75.1 ± 11.2 at baseline to 72.8 ± 11.2 beats/min at the end of the study (p = 0.06; not significant). Fifty percent (95% CI 41.6, 58.4) of the patients had microalbuminuria at baseline compared with 31.3% (95% CI 23.0, 39.6) at study end (p = 0.006). Reductions in mean ± SD fasting glucose levels (−10.2 ± 50.3 mg/dL; p < 0.05), HbA1c (−0.19 ± 0.97%; p = 0.05), total cholesterol (−11.9 ± 35.2 mg/dL; 95% CI −18.1, −5.8; p < 0.005), triglycerides (−10.8 ± 51.1 mg/dL; 95% CI −19.7, −1.8; p = 0.018) and low-density lipoprotein-cholesterol (−8.1 ± 27.7 mg/dL; 95% CI −13.2, −2.9; p = 0.002) were observed. No patients dropped out of the study because of adverse effects. The most frequent adverse effect encountered was malleolar oedema (9%).
Conclusion: Manidipine added as the third drug to a renin-angiotensin system inhibitor plus a low dose of diuretic significantly reduces BP, improves renal function, has favourable effects on the lipid and glucose profiles, and reduces microalbuminuria in uncontrolled hypertensive patients with type 2 diabetes. Long-term trials are necessary to evaluate time-related effects.