Prehypertension is associated with cardiovascular disease and insulin resistance. However, whether subjects with prehypertension have more diabetes risk is not known. Researchers David R. Mullican, MD, Carlos Lorenzo, MD, and Steven M. Haffner, MD, University of Texas Health Science Center San Antonio, examined whether prehypertension is a risk factor for developing Type 2 diabetes.
Incident diabetes was examined in nondiabetic normotensive participants in the San Antonio Heart Study (n = 2,767; aged 25-65 years; median follow-up 7.8 years).
The results showed that the Incident diabetes was 12.4% in subjects with prehypertension and 5.6% in subjects with normal blood pressure. The odds of incident diabetes were 2.21 greater for individuals with prehypertension than for those with normal blood pressure (95% CI 1.63-2.98) after adjusting for age, sex, and ethnicity. Prehypertension was not associated with incident diabetes after additional adjustment for BMI, impaired glucose tolerance, insulin resistance and secretion, and family history of diabetes (odds ratio 1.42 [95% CI 0.99-2.02]).
This study confirms previous reports on the relation of prehypertension to obesity and insulin resistance and demonstrates that individuals with prehypertension have higher rates of conversion to diabetes than those with normal blood pressure. Much of the diabetes risk associated with prehypertension is explained by disorders related to the insulin resistance syndrome.
Subjects with prehypertension have more diabetes risk than those with normal blood pressure regardless of sex, ethnicity, and categories of obesity and glucose tolerance. However, prehypertension is not associated with incident diabetes in subjects aged ≥50 years. Potential explanations may be a lack of statistical power (n = 752) or a lesser relationship between blood pressure and insulin resistance in individuals aged ≥50 years.
A significant limitation in this study is the lack of information on waist circumference, chronic inflammation, and physical activity for all participants. These confounders could be relevant for explaining the relationship between prehypertension and incident diabetes.
In summary, this study shows that subjects with prehypertension had greater risk of converting to diabetes than those with normal blood pressure. Much of this risk is explained by disorders related to the insulin resistance syndrome. Further study is needed regarding mechanisms of this phenomenon and treatment options for participants with prehypertension.
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