P1679HYPOMAGNESAEMIA AND HYPERGLYCAEMIA AFTER KIDNEY TRANSPLANTATION

Background and Aims Hypomagnesaemia has been associated with increased insulin resistance and decreased insulin secretion. Recent data suggest that early post-engraftment hypomagnesaemia may play a role in development of post-transplant diabetes mellitus (PTDM). This single-centre study investigated the association between hypomagnesaemia 8 weeks post-engraftment and glucose metabolism changes 1 year after kidney transplantation. Method The study included 425 renal transplantation recipients, transplanted at Oslo University Hospital between March 2015 and May 2018. All included patients had functioning grafts with valid blood sampling and oral glucose tolerance tests 8 weeks and 1 year after transplantation. Patients with known pretransplant diabetes and those developing PTDM the first 8 weeks after transplantation were excluded. The association between plasma magnesium 8 weeks after transplantation and HbA1c, fasting plasma glucose and 2-hr glucose after 1 year was tested using both unadjusted and multiple linear regression, adjusted for: gender, age, body mass index (BMI), systolic blood pressure (SBP), tacrolimus (trough), measured glomerular filtration rate (mGFR; iohexol clearance) and plasma triglycerides. Results Patients had a median age of 54 (range 18-83) years, 65% were men and mean mGFR 1 year after transplantation was 56 (SD±14) ml/min/1.73m2. Median plasma magnesium was 0.72 (0.46-0.94) mmol/L 8 weeks after Tx and patients with hypomagnesaemia (Mg< 0.7 mmol/L) (n=169) were not different compared to patients with normal plasma magnesium (n=256) regarding age, gender, BMI, tacrolimus, mGFR, SBP or plasma triglycerides after 1 year. In unadjusted linear regression 1 mmol/L higher plasma magnesium at 8 weeks was associated with the following glycaemic endpoints 1 year after transplantation (β-coefficient, CI 95%, p-value); fasting glucose: HbA1c: +9 mmol/mol (1;16, P=0.02); +0.5 mmol/L (-0.7;1.7, P=0.39); 2-hour glucose: +0.74 mmol/L (-2.5;3.9, P=0.65). In multiple linear regression the following numbers were: Fasting glucose: HbA1c: +8 mmol/mol (0.3;16, P=0.042); +0.7 mmol/L (-0.5;2.0, P=0.26); 2-hour glucose: +2.8 mmol/L (-0.6;6.2, P=0.11). Conclusion In both unadjusted and multiple linear regression there was a positive correlation between 8-week plasma magnesium and HbA1c 1 year after transplantation. A similar trend was found for fasting and 2-hour glucose, although this was not statistically significant.