High blood pressure is linked to increased risk of diabetes

People with high blood pressure have an almost 60% increased risk of developing type 2 diabetes, shows a study of more than four million people published in the Journal of the American College of Cardiology.1

Hypertension has long been recognised as an independent risk factor for cardiovascular events, but the relationship between blood pressure and the risk of new onset diabetes is less clear.

The researchers looked at the health records of 4.1 million patients free from vascular disease and diabetes in the UK Clinical Practice Research Datalink, an electronic health record system covering about 9% of the UK population. The patients all had at least one blood pressure measurement performed from 1990 to 2013. The median age of the population was 46, the median body mass index was 25.7, and 56% were women. The patients were linked to hospital episode statistics, and 186 698 new onset diabetes events were observed during a median follow-up of 6.8 years.

The researchers found that, for every 20 mm Hg increase in systolic blood pressure, the risk of new onset diabetes was 58% higher (hazard ratio 1.58 (95% confidence interval 1.56 to 1.59)). For every 10 mm Hg increase in diastolic blood pressure the risk of developing diabetes was 52% higher (1.52 (1.51 to 1.54)).

The study, which was funded by the UK National Institute for Health Research, found that higher blood pressure was also associated with a higher risk of new onset diabetes in a wide variety of groups, including men and women of different ages, overweight and obese people, and those of normal weight. The strength of the association declined with increasing BMI and age.

Kazem Rahimi, study author and deputy director of the George Institute for Global Health UK at the University of Oxford, said, “We can’t say for certain that one causes the other, but this study helps to connect the dots, showing that if you have high blood pressure there is a significantly greater chance of developing diabetes.” He added, “Understanding the link will help us better communicate risks to patients and can provide another motivation for patients and doctors to aim for tight blood pressure control.”

The findings were supported by the results of a meta-analysis of 30 other studies, including 285 664 participants and 17 388 incident diabetes events. This found that the pooled relative risk of diabetes with a 20 mm Hg higher systolic blood pressure was 1.77 (1.53 to 2.05).

The authors said that it was unclear whether the observed association between blood pressure and diabetes was causal and that further investigation was needed.

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