Contrasting mortality risks among subgroups of treated hypertensive patients developing new-onset diabetes

Hypertension and diabetes mellitus (DM) frequently cluster together and synergistically increase cardiovascular risk. Among those who develop DM during treatment for hypertension (new-onset diabetes, NOD), it is unclear whether NOD reflects a separate entity associated with increased risk or merely reflects accelerated presentation of DM.

We analysed data on 15 089 hypertensive patients attending the Glasgow Blood Pressure Clinic. The date at first hospital encounter either with diagnosis of diabetes or prescription of anti-hyperglycaemic medication were considered as the onset of diabetes. Cox proportional hazard models (including propensity score matching) were employed to study associations between diabetes status, early and late NOD (diagnosis <10 years or >10 years from first clinic visit) and cause-specific mortality. There were 2516 patients (16.7%) with DM, of whom 1862 (12.3%) had NOD [early NOD = 705 (4.6%); late NOD = 1157 (7.6%)]. The incidence rate of NOD was 8.2 per 1000 person-years. The total time at risk was 239 929 person-years [median survival: 28.1 years (inter-quartile range: 16.2-39.9)]. Compared with non-diabetic individuals, prevalent DM [hazard ratio (HR) = 1.8, 95% confidence interval (CI): 1.4-2.2] and time varying NOD status (HR: 1.09, 95% CI: 1.06-1.17) were associated with increased adjusted all-cause mortality. Early NOD (HR: 1.39, 95% CI: 1.2-1.6) was associated with increased in mortality risk, but not late NOD (HR: 0.92, 95% CI: 0.83-1.01). Results were consistent in the propensity score matched analyses.

Although 1-in-8 hypertensive patients develop NOD, mortality is increased only in the 1-in-20 who develop early NOD. Further studies are warranted to determine if early identification of such individuals should provide an alert for intensification of therapeutic interventions.