Effect of in-hospital glycemic variability on mortality in patients with diabetes. / Efecto de la variabilidad glucémica intrahospitalaria en la mortalidad de los pacientes con diabetes.

INTRODUCTION: 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. MATERIAL AND METHODS: 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. RESULTS: 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 >140mg/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 MBG >140mg/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 ≤140mg/dl. CONCLUSION: The simultaneous presence of a high MBG level and CV constitutes a powerful tool for stratifying mortality risk after hospital discharge.