Pioglitazone Lowers Blood Pressure in Patients With Diabetes

Introduction

Hypertension is frequently diagnosed in patients with type 2 diabetes mellitus. Both conditions carry an increased risk for cardiovascular and renal disease.^[1,2,3] Hypertension accelerates the development of microalbuminuria and retinopathy in type 2 diabetes, thus enhancing risks for vascular and renal complications.^{[1,3,4,5,6,7]} Tight control of blood pressure and glucose reduces progression of diabetic retinopathy and deterioration in visual acuity in these patients.^[8] Given the possibility of significant co-morbidities, physicians prescribing treatments that affect any of these aspects should also consider their impact on other aspects.^[9]

The most common approach to treating hypertension is through the use of antihypertensive drugs. While it is recognised that certain co-morbidities require special attention and must be addressed (e.g. hyperlipidaemia requires therapy with lipid-lowering agents), the fundamental problem of insulin resistance in hypertensive patients is rarely addressed.^[10] Hyperglycaemia, central (visceral) obesity, hypertension, dyslipidaemia, hyperinsulinaemia, endothelial dysfunction and impaired fibrinolysis are found in both type 2 diabetes and hypertension,^[9] as well as in the prediabetic state,^[11] but insulin resistance is the common metabolic disorder in patients with these two conditions.^[10]

Thiazolidinediones (also known as glitazones) represent a new class of oral antidiabetic agents. They activate the peroxisome proliferator-activated receptor (PPAR)-γ, thereby reducing insulin-resistance.^[12] The thiazolidinedione pioglitazone targets vascular insulin resistance in particular by improving endothelial dysfunction and inflammatory processes in the arterial wall.^[13,14] Clinical data clearly demonstrate that thiazolidinediones have blood pressure-lowering effects in hypertensive diabetic and non-diabetic patients.^{[13,15,16,17]}

There are numerous trials revealing a blood pressure-lowering effect of thiazolidinediones in diabetic patients as well as in non-diabetic patients. Most of these studies are well designed but have small sample sizes. It is therefore important to study the effects of thiazolidinediones in larger and unselected populations of patients with type 2 diabetes. The aim of this study was to investigate whether treatment with pioglitazone in an unselected population of patients with type 2 diabetes results in comparable blood pressure benefits to those reported in previous studies.