Effect of Renin Angiotensin System [RAS] Blockade on Blood Glucose Levels in Prediabetic Hypertensive Patients

Introduction: Patients with hypertension have an increased prevalence of type II diabetes mellitus and impaired glucose tolerance. Prevalence of prediabetes is increasing worldwide and experts have projected that more than 470 million people will have pre-diabetes by 2030. A proportion of 5-10% of people per year with pre-diabetes will progress to diabetes, with the same proportion converting back to normoglycemia. Blockade of Renin Angiotensin System [RAS] either by an Angiotensin converting enzyme (ACE) inhibitor or an Angiotensin receptor blocker (ARB) would slow down the progression of prediabetic state to diabetes.
Methods: This was an open labeled, prospective, observational cohort study and a total of 71 prediabetic hypertensive patients who were prescribed either an ACE inhibitor or ARB monotherapy were enrolled into the study. An oral Glucose Tolerance Test (GTT) was done in all the patients at baseline, end of 6 months and end of 1 year of treatment with RAS blockade.
Results: At the end of 1 year, out of cohort of 59 prediabetic hypertensive patients who completed the study, 28.81% were in the Normal glucose tolerance (NGT) group, 23.72% developed diabetes whereas 47.45% remained prediabetic at the end of study. In the prediabetic group, significant negative correlation was observed between Initial Systolic Blood Pressure (SBP1), Age, their interaction (Age × SBP1) and fall in GTT. Significant regression of fall in GTT with SBP1 and interaction of age and initial SBP (Age × SBP1) implies that initiation of treatment at an early age, at lower initial systolic blood pressure levels have a beneficial effect on the glucose tolerance state.
Conclusion: In prediabetic hypertensive patients, the blockade of RAS with either ACE inhibitor or ARB has significant preventive effect on the progression of Type II DM. The beneficial effect is more marked if the RAS based pharmacotherapy is initiated at low initial systolic blood pressure, especially at a relatively younger age. The exact nature of beneficial role of RAS blockade in addition to their hypotensive effect should be investigated by further studies.