Relationship between vitamin D and post-transplant diabetes mellitus in kidney transplant recipients

Post-transplant diabetes mellitus (PTDM) adversely affects graft survival and is an independent predictor of adverse cardiovascular events. Observational studies in the general population as well as the post-transplant setting suggest an association between the plasma 25-hydroxyvitamin D [25(OH)D] level and onset of type 2 diabetes mellitus. Literature is very limited in the context of PTDM.

To study the relationship between vitamin D deficiency at the time of kidney transplant and PTDM in the post-transplant period.

In this single center study, 72 patients who underwent kidney transplant were included. Blood samples for serum vitamin D level were collected on the day of transplant and analyzed at the end of study. The LIAISON^® 25(OH)D assay was used for quantitative estimation of total 25(OH)D in the serum. PTDM was diagnosed by either fasting plasma glucose (> 126 mg/dL), 2-h post prandial plasma glucose (> 200 mg/dL), or 2-h oral glucose tolerance test after 45 days post-transplant. Hemoglobin A1c was not used to diagnose PTDM. Vitamin D levels were labeled as sufficient (≥ 30.0 ng/mL), insufficient (20.0-29.9 ng/mL), and deficient (< 20.0 ng/mL). Patients were reviewed at 45 days and 1 year post transplant for the occurrence of PTDM.

In our study cohort 72 patients completed the study. Overall, 32 (43.8%) patients developed PTDM during the follow up of 1 year, 44 (61.1%) patients had deficient (< 20 ng/mL) 25(OH)D levels. Twenty-six (81.2%) patients with PTDM had deficient vitamin D levels as compared with 18 (45.0%) patients without PTDM (P = 0.007). This association was also significant when univariable [odds ratio (OR) = 5.3, 95% confidence interval (CI): 1.79-15.67, P = 0.003)] and multivariable (OR = 8.21, 95%CI: 2.19-30.75, P = 0.002) regression analysis was performed. A higher proportion of subjects having PTDM (15.6%) had a positive family history of diabetes mellitus than the controls (2.5%) (P = 0.045). However, this association did not persist in the multivariable regression analysis (OR = 12.6, 95%CI: 0.86-185.4, P = 0.065).

Deficient vitamin D levels (< 20 ng/mL) were significantly associated with PTDM in the post kidney transplant setting. Further studies are needed to see the effect of vitamin D replacement on PTDM.