Effect of in-hospital glycemic variability on mortality in patients with diabetes

The aim of this study was to evaluate the impact of mean blood glucose (MBG) and glycaemic variability (GV) during hospitalisation on mortality after discharge.

We conducted a retrospective longitudinal analytical cohort study that included patients discharged form a department of internal medicine with a diabetes-related diagnosis. The evaluated prognosis was mortality. During hospitalisation, the patients' clinical, laboratory and glycaemic control-related variables were recorded (MBG, GV and hypoglycaemia). The GV was measured with the coefficient of variation (CV). We calculated the mortality rates for every 1000 patient-years and compared them with Kaplan-Meier curves. We determined the predictors of mortality by performing a Cox regression.

The study included 276 patients with a mean age of 77.6 (SD, 10.2) years. The median outpatient follow-up duration was 2.7 years. In the multivariate analysis, an MBG > 140 mg/dL (HR = 1.72; 95% CI 1.14-2.61; p = .01) and a CV > 0.29 (HR = 1.52; 95% CI 1.12-2.06; p = .006), but not the presence of hypoglycaemia, were additively and independently associated with an increased risk of mortality. An MG > 140 mg/dL with a CV > 0.29 increased the mortality rates (123 vs. 317 per 1000 patient-year; p < .001) and the adjusted mortality risk (HR = 2.70; 95% CI 1.71-4.27; p < .001) compared with having an MBG ≤ 140 mg/dL.

The simultaneous presence of a high MBG level and CV constitutes a powerful tool for stratifying mortality risk after hospital discharge.