Response to Masked hypertension in untreated and treated patients with diabetes mellitus: attractive but questionable interpretations and response to Is masked hypertension related to diabetes mellitus?

We agree with Drs Sobiczewski and Wirtwein that a selfreported diagnosis of diabetes mellitus or the use of antidiabetic drugs may not provide an accurate prevalence of the disease, in particular because of the somewhat different criteria used in the 11 cohorts included in the International Database on Ambulatory blood pressure in relation to Cardiovascular Outcomes (IDACO).1 However, misclassification of diabetes mellitus should weaken, not strengthen, the results of our study. In reply to the comments on ambulatory blood pressure (BP) measurement, we standardized the definitions of daytime and nighttime across cohorts taking into account the differences in the pattern of daily activities between Europe and Asia (see Expanded Methods in the onlineonly Data Supplement).1 Moreover, to account for the varying intervals between ambulatory BP readings, we computed timeweighted BP means of the daytime BP (see Expanded Methods in the online-only Data Supplement).1 In terms of the comparison of cardiovascular risk between untreated diabetic patients with masked hypertension versus untreated diabetic patients with stage-1 hypertension,1 we wish to correct a misconception. The risk was equal with a hazard ratio of 1.07 (95% confidence interval, 0.58\u20131.98; P=0.82). In addition, the hypothesis that we may have underdiagnosed untreated masked hypertension in the patients with diabetes mellitus by using the daytime rather than the nighttime ambulatory BP was put to the test. Of the 229 untreated diabetic patients with normotension by office reading, there were 67 (29.3%) versus 56 (24.5%) patients with masked hypertension as identified by elevated daytime versus nighttime BP, respectively. However, use of daytime versus nighttime BP to define masked hypertension led to discrepant diagnoses in 22.2% of the untreated patients with diabetes mellitus. There is abundant evidence in the diabetic and other high-risk hypertensive states that nocturnal BP, alone or together with daytime BP, is a superior predictor of cardiovascular risk than daytime BP alone.2\u20134 In the current study in untreated patients with diabetes mellitus, masked hypertension, either defined using daytime BP (hazard ratio, 1.96; confidence interval, 0.97\u20133.97; P=0.059) or nighttime BP (hazard ratio, 3.44; confidence interval, 1.68\u20137.06; P