Comparison of glycemic control and variability in patients with type 2 and posttransplantation diabetes mellitus

Aim: Posttransplantation diabetes mellitus (PTDM) is a common complication after renal transplantation leading to increased cardiovascular morbidity and mortality. In subjects with type 2 diabetes (T2DM) increased glycemic variability and poor glycemic control have been associated with cardiovascular complications. We therefore aimed at determining glycemic variability and glycemic control in subjects with PTDM in comparison to T2DM subjects. Methods: In this observational study we analyzed 10 transplanted subjects without diabetes (Control), 10 transplanted subjects with PTDM, and 8 non-transplanted T2DM subjects using Continuous Glucose Monitoring (CGM). Several indices of glycemic control quality and variability were computed. Results: Many indices of both glycemic control quality and variability were different between control and PTDM subjects, with worse values in PTDM. The indices of glycemic control, such as glucose mean, GRADE and M-value, were similar in PTDM and T2DM, but some indices of glycemic variability, that is CONGA, lability index and shape index, showed a markedly higher (i.e., worse) value in T2DM than in PTDM (P value range: 0.001-0.035). Conclusions: Although PTDM and T2DM subjects showed similar glycemic control quality, glycemic variability was significantly higher in T2DM. These data underscore potential important pathophysiological differences between T2DM and PTDM indicating that increased glycemic variability may not be a key factor for the excess cardiovascular mortality in patients with PTDM.