Increased long-term risk of new-onset diabetes mellitus in white-coat and masked hypertension

OBJECTIVE: A sustained blood pressure elevation is associated with an increased risk of new-onset diabetes mellitus. Whether this is the case also in white-coat and masked hypertension is unknown. METHODS: In 1412 individuals of the Pressioni Arteriose Monitorate E Loro Associazioni study stratified for sex and age decades, we measured office, home and 24-h ambulatory blood pressure together with fasting plasma glucose and other metabolic variables. This allowed to identify patients with white-coat, masked, sustained hypertension and true normotension. RESULTS: Over a 10-year period, the increase in plasma glucose and the incidence of new-onset diabetes (plasma glucose ≤126 mg/dl or use of antidiabetic drugs) was significantly greater in individuals with white-coat and masked hypertension than in those with 'true' normotension (age and sex-adjusted risk 2.9 and 2.7, respectively), the increase being similar to that of sustained hypertensive individuals. The adjusted risk showed a marked increase when development of an impaired fasting glucose condition was also considered, and the results were similar when individuals reporting antihypertensive drug treatment were excluded or white-coat and masked hypertension were identified by office versus home blood pressure. The increased risk of new-onset diabetes become no more significant when data were adjusted for initial blood glucose and BMI, which, at a multivariate analysis, were the most significant predictors of this condition, with only a small although significant contribution of the initial blood pressure. CONCLUSION: Thus, white-coat and masked hypertension are associated with a long-term greater progression of blood glucose abnormalities and an increased risk of developing diabetes. This is largely accounted for by the metabolic abnormalities that are frequent components of these conditions.