RESUMO
Background Diabetic nephropathy (DN) is a significant cause of morbidity and mortality in young adults with type 1 diabetes (T1D). Microalbuminuria (MA) is generally considered as the earliest manifestation of DN. However, it has been shown that MA may be temporary and not reflect permanent renal failure. For this reason, sensitive markers are needed for the detection of kidney damage in the early period. Urinary tubular injury markers increase in the early period of diabetes. These tubular markers are rather indicators of acute renal damage. The objective of this study was to measure the urinary netrin-1 level, a marker of tubular injury in children with normoalbuminuric (NA) T1D, and to determine its relationship with short-term fluctuations in blood glucose using fructosamine levels. Methods Netrin-1 levels in spot urine samples from 82 children with T1D (median age 13.6 years) without MA or hypertension and from 59 healthy controls (median age 11.3 years) with a similar distribution of age and body mass index (BMI) were compared. The relationship of the netrin-1 levels with diabetes parameters such as fructosamine, hemoglobin A1c (HbA1c) or duration of diabetes was investigated. Results Urinary netrin-1 level was found to be higher in patients with T1D than in healthy controls (590 [interquartile range (IQR) = 811] pg/mg-creatinine [pg/mg-cr] and 396 [IQR = 742] pg/mg-cr, respectively) (p = 0.03). Urinary netrin-1 was found to correlate with HbA1c (p = 0.007, r = 0.320) and fructosamine (p = 0.04, r = 0.310) but not with average HbA1c in the last year (p = 0.14, r = -0.19), duration of diabetes (p = 0.83, r = 0.02) or other diabetes indices. Conclusions These results support the idea that tubular damage occurs early in the course of diabetes. However, the fact that netrin-1 is related to fructosamine and HbA1c but not to the duration of diabetes or average HbA1c in the last year may suggest that the tubular damage markers are affected by short-term fluctuations in blood glucose.