The impact of abnormal glucose regulation on arterial stiffness at 3 and 15 months after kidney transplantation

Background: Post-transplant diabetes mellitus (PTDM) has been associated with an increased risk of cardiovascular disease (CVD) mortality following kidney transplantation, but the association between pre-diabetes (i.e. impaired fasting glucose and impaired glucose tolerance) and CVD mortality remains unclear. The aim of this study was to assess the association between abnormal glucose regulation and arterial stiffness at 3 and 15 months post-transplantation. Methods: This is a single-centre prospective cohort study of 83 non-diabetic kidney transplant recipients who received a kidney transplant between 2008 and 2011. All patients underwent an oral glucose tolerance test (OGTT – categorised as normal, pre-diabetes or PTDM) and non-invasive measurements of arterial stiffness (aortic pulse wave velocity [PWV] and augmentation index [AIx]) 3 months post-transplantation. A sub-set of patients had repeat OGTT (n= 33) and arterial stiffness measurements (n=28) at 15 months post-transplant. Results: Of the 83 patients, 52% (n=43) had normal glucose regulation, 31% (n=26) had pre-diabetes and 17% (n = 14) developed PTDM. Compared with recipients with normal glucose regulation, recipients with PTDM (adjusted β= 5.61, 95% confidence interval [CI] 0.09 to 11.13, p = 0.047) but not those with pre-diabetes (adjusted β= 3.23, 95% CI -1.05 to 7.51, p = 0.137) had significantly higher AIx 3 months after transplantation. No association was found between glucose regulation and PWV at 3 months after transplantation. There was no association between glucose regulation at 3 or 15 months and AIx and PWV at 15 months in a subset of recipients. Conclusions: Early onset PTDM is associated with increased systemic vascular stiffness (AIx) but not regional stiffness of large arteries (PWV) suggesting that small vessel dysfunction may be the earliest vascular change seen with PTDM. Thus, measurements of arterial stiffness after transplantation may assist in more accurately stratifying future CVD risk of kidney transplant recipients.