New onset hyperglycemia and diabetes are associated with increased cardiovascular risk after kidney transplantation

Background. Post-transplant diabetes (PTDM) is a common and serious complication of kidney transplantation. The implications of developing hyperglycemia of lesser severity are not well understood. Methods. In this study we used American Diabetes Association (ADA) criteria to assess the incidence of abnormal glycemia post-transplant, the variables that relate to this complication, and the relationship between hyperglycemia and cardiovascular (CV) disease. Included in the study were 490 kidney recipients, transplanted from 1998 to 2003, without a history of diabetes, and with a pretransplant fasting glucose <126 mg/dL. Results. Within one week post-transplant, 45% of recipients had impaired fasting glycemia (IFG, glucose 100-125 mg/dL), and 21% PTDM (glucose ≥126). One year post-transplant, 33% of patients had IFG, and 13% PTDM. Risk factors for hyperglycemia at one year included: older recipient, male gender, higher BMI, higher pretransplant glucose, and higher glucose one week post-transplant (all P < 0.002 by multivariable analyses). During a follow-up period of 40 ± 14 months, 12% of recipients had CV events (cardiac, CVA, and/or peripheral). Increasing fasting glucose levels at one, four, and/or 12 months post-transplant were significantly related to CV events. Furthermore, these relationships were independent of other CV risk factors, including: older age, CV events pretransplant, male gender, dyslipidemia, and transplant year. Fasting glucose levels >100 mg/dL were associated with higher incidence of post-transplant cardiac (P = 0.001) and peripheral vascular disease events (P = 0.003). Conclusion. The incidence of post-transplant hyperglycemia and its CV impact have been underestimated. Pretransplant characteristics and, particularly, the glycemia during the first month post-transplant identified patients at risk of PTDM. Increasing glucose levels greater than 100 mg/dL, any time after the first month post-transplant, are associated with increasing CV risk. We postulate that aggressive detection and treatment of post-transplant hyperglycemia may significantly reduce CV morbidity and mortality after kidney transplantation.