Albuminuria in diabetic patients: How to measure it?-a narrative review

Diabetes is the leading cause of chronic kidney disease (CKD) and end stage renal disease (ESRD) worldwide. Glomerular filtration rate (GFR) and urine albumin to creatinine ratio (ACR) define the severity of CKD and predict cardiovascular outcomes of patients with CKD. ACR is preferred over protein to creatinine ratio (PCR) because of a greater sensitivity for low level of proteinuria, higher reproducibility in between laboratories and better cardiovascular risk stratification. Interventions aiming at decreasing ACR [such as use of renin-angiotensin-aldosterone system (RAAS) or more recently, sodium glucose cotransporter type 2 inhibitors (SGLT2is)] slow down the rate of progression of CKD. Therefore, global recommendations state that ACR needs to be assessed at least once a year, ideally on an early morning void, in patients with diabetes or CKD. However, quantification of urinary albumin is not standardized yet and heterogeneity in the laboratory methods available or expression of albuminuria may lead to misinterpretation of ACR. Pre-analytical considerations such as characterisation of the urinary sediment is also important as abnormalities (infection or haematuria) may interfere with the ACR. Moreover, atypical features such as an active sediment, fast progression of albuminuria or decline in GFR, short duration of diabetes, absence of diabetic retinopathy, nephrotic syndrome, must lead to further investigation since non-diabetic renal disease is not rare in patients with diabetes and might benefit from targeted therapeutics. Nephrologists and diabetologists should be aware of these limitations when interpreting the results in order to offer incisive and adequate therapeutic management.