Longevity Briefs: Can Blood Pressure Lowering Drugs Prevent Type II Diabetes?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

Why is this research important: Type II diabetes is one of the most common and most deadly chronic diseases of ageing, in part because it increases the risk of most other major chronic diseases. Among these are atherosclerosis (in which major blood vessels become increasingly occluded by the growth of fatty plaques) and other conditions related to the blood vessels, such as diabetic retinopathy (in which high blood sugar damages blood vessels in the eyes). Treatment aimed at lowering blood pressure can reduce the risk of these diseases in diabetics, but can they also reduce the risk of becoming diabetic in the first place?

What did the researchers do: Here, researchers conducted a meta analysis of data concerning the effects of five major classes of blood pressure lowering drugs on the risk of new-onset type II diabetes. The data came from 22 randomised studies carried out between 1973 and 2008 in which the drug under investigation was compared to a placebo or other class of blood pressure lowering drug.

Key takeaway(s) from this research: A reduction in systolic blood pressure (the pressure during cardiac contraction) of 5 mmHg was associated with an 11% reduction in type 2 diabetes incidence after a median follow-up of 4.5 years. However, not all treatments were beneficial: drugs belonging to the ACE inhibitor and ACE receptor blocking classes were associated with a similar risk reduction, but calcium channel blockers had no significant effect, while thiazide diuretics and beta blockers were actually associated with an increased risk of type II diabetes.

These findings could have important implications for the choice of antihypertensive drug for people with heart disease, as it suggests that while lowing blood pressure is on average associated with a reduction in diabetes risk, some classes of drug may increase risk through their off-target actions. Previous studies that have posed similar questions to this study have reported conflicting results, but most of these were observational and were not randomised trials, making them vulnerable to confounding factors. Because this meta-analysis looked only at randomised, placebo controlled trials, the observed relationships are more likely to be causal.

One thing that this study did not investigate was the effects of treatment with a combination of drugs from different classes. This is noteworthy because it is very common for a patient to receive multiple different classes of antihypertensive drug. The authors also note that information on drug dosage in the studies was incomplete, meaning that the results could be reflective of different drug dosages across the studies.

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