High BP greatly increases women's diabetes risk

10 October 2007

MedWire News: Women with high blood pressure (BP) levels are three times more likely to develop Type 2 diabetes than those with optimal BP levels, irrespective of their body mass index (BMI) and presence of other cardiovascular and diabetes risk factors, US study findings reveal.

The authors report in the European Heart Journal that both baseline BP and BP progression strongly predict incident Type 2 diabetes in initially healthy women, and say their findings highlight the need to consider cardiovascular risk factors in combination.

David Conen (Harvard Medical School, Boston, Massachusetts, USA) and colleagues followed-up over 38,000 female health professionals enrolled in the Women's Health Study for 10 years. The women were all free of diabetes and cardiovascular disease at study entry.

"Despite several studies finding a close relationship between hypertension and Type 2 diabetes, little information exists on the relationship between BP levels and the subsequent development of Type 2 diabetes," explained Conen. "Data for women are particularly limited."

The team divided the women into four groups: those with optimal BP (<120/75 mmHg); those with normal BP (120-129/75-84 mmHg); those with high normal BP (130-139/85-89 mmHg); and those with established hypertension (≥140/90 mmHg), and/or self-reported history of hypertension or antihypertensive treatment.

At follow-up, the incidence of Type 2 diabetes was 1.4% in the optimal BP group, 2.9% in those with normal BP, 5.7% in high-normal BP participants, and 9.4% in the established hypertension group.

Multivariable adjusted hazard ratios (HRs) for diabetes across the BP categories were 0.66, 1.00 (referent group), 1.45, and 2.03 (p for trend <0.0001).

Stratification by BMI gave similar results. "Analyses showed that the relationship... was similar among women who were normal weight, overweight, or obese," Conen reported. "There was a three-fold increase in risk from the lowest to the highest BP category within all three weight categories."

Women whose BP increased over time during the study also had an increased risk for developing diabetes. Adjusted HRs for incident diabetes at 2 years among women who had no BP progression, those in whom BP increased but remained normotensive, and women who developed hypertension were 1.0, 1.26, and 1.64, respectively, compared with 2.39 in women with baseline hypertension (p for trend <0.0001).

The authors conclude: "Our findings provide strong evidence that BP and progression of BP are associated with an increased risk of diabetes. They highlight the fact that cardiovascular risk factors are interrelated and occur in clusters.

"Thus, an important message for physicians and future guidelines is that none of the cardiovascular risk factors should be looked at individually. The combination of all risk factors should be used to make treatment decisions."

Eur Heart J 2007; Advance online publication