CGM metrics as indicators of graft function in islet transplant recipients

CGM metrics as indicators of graft function in islet transplant recipients

W.E.M.E. de Vos1, M. Ajie1, C.P. Landstra1, R.D. Hauck1, M.C. Tol1, D.J. Cornelissen1, M.A. Engelse1, E.J.P. de Koning1

Internal Medicine, Leiden University Medical Center, The Netherlands


 Allogeneic and autologous islet transplantation (ITx) is performed to stabilise glycaemic control by restoring endogenous insulin secretion. Continuous glucose monitoring (CGM) is used to monitor and improve glycaemic control post-ITx. We explored the relationship between specific CGM metrics and islet graft function during follow-up.


 Clinical outcome parameters from islet transplantation recipients were analysed up to one year post-ITx. We determined the area under the C-peptide curve (AUCC-peptide) during a mixed meal tolerance test (MMTT) to assess islet graft function at 3 months and 1 year. Averaged CGM metrics two weeks pre-MMTT included time in range (TIR), time in tight range (TITR), glucose management indicator (GMI), glucose variability (%CV) and glycaemia risk index (GRI= (3.0×VeryLow)+(2.4×Low)+(1.6×VeryHigh) + (0.8×High)). Graft function and CGM metrics data at 3 months and 1 year were pooled for analysis. Using mixed model testing we determined the relationship between these parameters and islet graft function.


 We analysed 34 islet transplantations (20 allogeneic/14 autologous) in 33 recipients (47% female; BMI 24.4±2.0 kg/m2; age 49.8±11.1years). Clinical outcomes regarding CGM metrics and graft function during follow-up are presented in Table 1. Overall, better CGM metrics were present at month 3 compared to year 1 while graft function remained stable. AUCC-peptide as a measure of graft function was strongly positively correlated with TIR (r=0.69, 95%CI [0.52,0.81], P<0.001) and TITR (r=0.64, 95%CI [0.44,0.77], P<0.0001). Glucose variability %CV (r=-0,70, 95%CI [-0.81,-0.53], P<0.001), GRI (r=-0.70, 95%CI [-0.82,-0.53], P=<0.001) and GMI (r=-0.44, 95%CI [-0.64,-0.19], P<0.001) were inversely correlated with graft function (AUCC-peptide).


 In conclusion, TIR, TITR, %CV and GRI may be used as indicators of islet graft function.