Comment on Cundy et al. Early Worsening of Diabetic Nephropathy in Type 2 Diabetes After Rapid Improvement in Chronic Severe Hyperglycemia. Diabetes Care 2021;44:e55–e56

We were interested in the recent article by Cundy et al. (1), who described a rapid and durable decline of estimated glomerular filtration rate (eGFR) in four subjects with type 2 diabetes after their HbA1c had fallen from 118 mmol/mol (12.9%) to 48 mmol/mol (5.5%). Fifteen years ago, we reported that GFR and its estimations correlated with HbA1c, each +1% (+9 mmol/mol) HbA1c being associated with +5–6 mL/min/1.73 m2 GFR (2). One could then fear a –35 mL/min/1.73 m2 GFR reduction after a rapid –7% reduction of HbA1c. We have recently shown that a dramatic reduction of HbA1c, by more than 27 mmol/mol (–3%), could be detected during the years preceding admission in 13.5% of 680 patients hospitalized …