We evaluated the performance of creatinine-based estimating equations for glomerular filtration rate (GFR) in adults with type 2 diabetes without nephropathy compared to measured GFR by gold-standard inulin clearance methods. mGFR was performed 4 times over the course of a 1 month treatment period in the context of a small randomized placebo-controlled trial measuring the intrarenal hemodynamics function responses to the dipeptidyl peptidase 4 inhibitor sitagliptin. Thirty-two adults with type 2 diabetes (randomized 1:1 to placebo or sitagliptin) completed the trial, and all participants underwent mGFR by inulin clearance and GFR estimated by serum creatinine using the MDRD (eGFRMDRD) and CKD-EPI (eGFRCKD-EPI). Performance of eGFR equations was evaluated using measurements of bias (mean difference), precision (standard deviations [SD]), and inaccuracy (defined as the proportion of eGFR that differed by >20% of mGFR). The effects of treatment and time on bias were evaluated using linear mixed effects models. Mean±SD age, diabetes duration, HbA1c, and BMI was 60±8 years, 9±7 years, 7.2±0.8%, and 31.0±6.2 kg/m2, respectively, and 12(38%) participants were female. At baseline, mean mGFR was 113±24, mean eGFRMDRD was 93±12, and mean eGFRCKD-EPI was 94±9, all in mL/min/1.73m2. When all 128 observations (32 participants measured 4 times) were evaluated, both equations substantially underestimated mGFR. For the eGFRMDRD, mean bias was -21.5 mL/min/1.73m2, precision was 22.7 mL/min/1.73m2, and 46% of observations differed by more than 20%. Results were similar for eGFRCKD-EPI. No time or treatment effects on bias were observed. In adults with type 2 diabetes, eGFR equations underestimated mGFR, lacked precision and accuracy, and had lower performance at higher ranges of mGFR. More accurate measures of kidney function may improve clinical decision-making in adults with type 2 diabetes.


J.A. Lovshin: Other Relationship; Self; AstraZeneca. Consultant; Self; Novo Nordisk Inc.. Research Support; Self; Sanofi, Merck Sharp & Dohme Corp.. Other Relationship; Self; Novo Nordisk Inc.. L. Lovblom: None. P. Bjornstad: Consultant; Self; Boehringer Ingelheim GmbH. Y. Lytvyn: None. H. Rajasekeran: None. D. Scarr: None. B.A. Perkins: Advisory Panel; Self; Boehringer Ingelheim GmbH. Research Support; Self; Boehringer Ingelheim GmbH, Novo Nordisk Inc.. Advisory Panel; Self; Novo Nordisk Inc., Abbott. Speaker's Bureau; Self; Abbott, Janssen Pharmaceuticals, Inc.. Advisory Panel; Self; Insulet Corporation. Speaker's Bureau; Self; Insulet Corporation, Dexcom, Inc. D. Cherney: Consultant; Self; AbbVie Inc.. Other Relationship; Self; AstraZeneca, Boehringer Ingelheim GmbH, Eli Lilly and Company. Consultant; Self; Sanofi. Other Relationship; Self; Merck & Co., Inc.. Consultant; Self; Mitsubishi Tanabe Pharma Corporation. Other Relationship; Self; Janssen Pharmaceuticals, Inc..

Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. More information is available at http://www.diabetesjournals.org/content/license.