Temporal variation of renal function in people with type 2 diabetes mellitus: a retrospective UK Clinical Practice Research Datalink cohort study.

AIMS: Renal function, measured by estimated glomerular filtration rate (eGFR), varies over time. This study aimed to characterize the longitudinal variability of eGFR in people with type 2 diabetes mellitus (T2DM), including variation between categories and individuals.

METHODS: People with T2DM and sufficient recorded serum creatinine measurements were identified from the Clinical Practice Research Datalink (T2DM diagnosis from 1st January 2009-1st January 2011 with five years' follow-up). eGFR was calculated using the CKD-EPI equation.

RESULTS: 7,766 individuals were included; 32.8%, 50.2%, 12.4%, 4.0% and 0.6% were in GFR categories G1, G2, G3a, G3b and G4, respectively. Overall, eGFR decreased by 0.44 mL/min/1.73m2 per year; eGFR increased by 0.80 mL/min/1.73m2 between index and year 1, then decreased by 0.75 mL/min/1.73m2 annually up to year 5. Category G1 showed a steady decline in eGFR over time; G2, G3a and G3b showed an increase between index and year 1, followed by a decline. Category G4 showed a mean eGFR increase of 1.85 mL/min/1.73m2 annually. People in categories G3-G4 moved across a greater number of GFR categories than those in G1 and G2. Individual patients' eGFR showed a wide range of values (change from baseline at year 5 varied from -80 to +59 mL/min/1.73m2 ).

CONCLUSION: Overall, eGFR declined over time, although there was considerable variation between GFR categories and individuals. This highlights the difficulty in prescribing many glucose-lowering therapies, which require dose adjustment for renal function. The study also emphasizes the importance of regular monitoring of renal impairment in people with T2DM. This article is protected by copyright. All rights reserved.