Introduction: The plethora of data on glycemic excursions and additional indices, such as the glycemic variability (GV) and glucose management indicator (GMI), which is an estimated A1C derived from the glucose measures that the continuous glucose monitoring (CGM) system provides, has revolutionized the study of dysglycemia on various organs and stress induced situations. GV has been proposed to be a risk factor for complication of diabetes and increased mortality and predictive marker for hypoglycemia. The purpose of this study was to describe the changes in glycemic patterns of kidney transplant recipients during the perioperative period using CGM and attempt to define the clinical significance of the glycemic variability that occur.

Method: A prospective observational study starting May 1st, 2021 was conducted for patients who underwent kidney transplantations at our center. Upon enrollment, a CGM system was applied and CGM was undertaken 2 weeks preoperatively and 2 weeks postoperatively. No additional interventions were undertaken. Clinical characteristics and transplant related outcomes were collected along with glucose profile using the CGM system.

Results: By March 1, 2022, a total of 72 patients were enrolled in the study and completion of both preoperative and postoperative CGM was accomplished in 51 patients. A hyperglycemic tendency was seen postoperatively than preoperatively with higher mean glucose levels (110.49±38.65 mg/dL vs. 134.24±32.74 mg/dL; p=<0.001), longer time above glucose level of 250mg/dL (3.13±9.19% vs. 4.24±8.118%; p=0.001), higher daily peak glucose levels (129.52±52.32mg/dL vs. 160.58±42.47mg/dL; p=<0.001), higher daily nadir glucose levels (85.84±26.73mg/dL vs. 105.27±27.83mg/dL p=<0.001). The GV and GMI as measured by the CGM system were also significantly increased from preop to postop; 28.48±7.78% vs. 32.70±9.05%, p=0.004 and 5.91±0.92% vs 6.89±2.51%, p=<0.001, respectively. Linear correlations fitted for postoperative glucose variability showed a positive correlation with preoperative glucose variability (r=0.40; p=0.006) and postoperative one-month hbA1c (r=0.35; p=0.023). A negative correlation with postoperative glucose variability and postoperative one-month fasting insulin (r=0.40; p=0.009), HOMA-B (r=-0.34; p=0.0029) and c-peptide (r=-0.49; p=0.001) was seen.

Conclusion: The continuous glucose monitoring of kidney transplantation recipients showed an overall hyperglycemic change in the post-transplant period with increased GV that was also reflected by an increase GMI and correlation with postoperative 1 month hbA1c. The negative correlations with postoperative GV and postoperative 1 month fasting insulin, c-peptide and HOMA-B values may relate to GV as a predictive marker of hypoglycemia, as reported in other studies. However, as an interim report of an ongoing prospective study, no conclusive statements about clinical significance could be made.