Estimated glomerular filtration rates cannot replace measured GFR in type 1 diabetes patients with hyperfiltration.

AIM: This study of children and young adults with type 1 diabetes with normal to high glomerular filtration rates (GFR) compared estimated GFR (eGFR) with measured GFR (mGFR).

METHODS: GFR was measured by inulin clearance, and we carried out simultaneous analyses of standardised creatinine and cystatin C. eGFR was calculated using different formulas.

RESULTS: We enrolled 106 patients, including 56 males, aged 21.9 (standard deviation 9.2) years with 13.7 (9.1) years' duration of diabetes and a mean haemoglobin A1c (HbA1c ) of 7.7% (61 mmol/mol). The median mGFR was 128 (111-143) mL/min/1.73 m(2) . Most of the eGFR estimations failed to detect a significant proportion of hyperfiltration based on inulin clearance. The best accuracy (P30) between eGFR and mGFR was seen with eGFRCKD - EPI (92%), eGFRcys C Berg (86%), eGFRcys C CAPA (78%) and eGFRcys C Inker (84%) where eGFRCKD - EPI and eGFR cys C Berg showed the lowest bias. Most eGFRcys C measurements showed greater accuracy when combined with eGFRcr (P30 92-94%).

CONCLUSION: The best accuracy (P30) and lowest bias were found with eGFRCKD - EPI and eGFR Berg. in this cohort. However, eGFR cannot accurately replace mGFR to detect hyperfiltration and follow GFR over time in young patients with type 1 diabetes.