The Effect of Diabetes and the Diabetogenic TBC1D4 p.Arg684Ter Variant on Kidney Function in Inuit in Greenland
Abstract ObjectiveDiabetes prevalence in Greenland is high and increasing. The aim of this study was to examine the effect of diabetes and the diabetogenic TBC1D4 variant on kidney function in Greenland in a population-based setting.Research Design and MethodsHealth survey data and TBC1D4 genotypes from 5,336 Greenlanders was used to estimate odds ratios (ORs) of albuminuria (>30 mg/g creatinine) and chronic kidney disease (CKD, eGFR<60 ml/min/1.73m2), comparing individuals with and without diabetes. Using baseline and follow-up data from individuals who participated in two surveys we examined the effect of diabetes on eGFR and urinary albumin creatinine ratio (UACR) at follow-up, stepwise adjusting for baseline confounders including the TBC1D4 variant.ResultsA total of 9.3% had diabetes of the 3,909 participants with complete data. Albuminuria and CKD was found in 27.6% and 9.5% among those with and without diabetes respectively. Diabetes was associated with increased risk of albuminuria (OR(95% CI) = 2.37 (1.69,3.33) p<0.001) and the TBC1D4 variant protected against albuminuria (OR(95% CI) = 0.44 (0.22,0.90) p=0.02) in a multivariable model. Neither diabetes nor the TBC1D4 variant significantly associated with CKD. Diabetes was not associated with changes in eGFR or UACR over a median of 11.3 years.ConclusionDiabetes conferred increased risk of albuminuria and the TBC1D4 variant was associated with decreased risk of albuminuria, but neither were associated with CKD. The presence/absence of diabetes did not predict changes in eGFR and UACR in longitudinal analyses. The potential renoprotective association of the TBC1D4 variant on albuminuria calls for further studies.