The effect of obesity and type 1 diabetes on renal function in children and adolescents.

Background: Early signs of renal complications can be common in youths with type 1 diabetes (T1D). Recently, there has been an increasing interest in potential renal complications associated with obesity, paralleling the epidemics of this condition, although there are limited data in children. Hypothesis: Obese children and adolescents present signs of early alterations in renal function similar to non-obese peers with T1D. Subjects: Eighty-three obese (age: 11.63.0yr), 164 non-obese T1D (age: 12.43.2yr), and 71 non-obese control (age: 12.33.2yr) children and adolescents were enrolled in the study. Methods: Anthropometric parameters and blood pressure were measured. Renal function was assessed by albumin excretion rate (AER), serum cystatin C, creatinine and estimated glomerular filtration rate (e-GFR), calculated using the Bouvet's formula. Results: Obese and non-obese T1D youths had similar AER [8.9(5.9-10.8) vs. 8.7(5.9-13.1) mu g/min] and e-GFR levels (114.8 +/- 19.6 vs. 113.4 +/- 19.1mL/min), which were higher than in controls [AER: 8.1(5.9-8.7) mu g/min, e-GFR: 104.7 +/- 18.9mL/min]. Prevalence of microalbuminuria and hyperfiltration was similar between obese and T1D youths and higher than their control peers (6.0 vs. 8.0 vs. 0%, p=0.02; 15.9 vs. 15.9 vs. 4.3%, p=0.03, respectively). Body mass index (BMI) z-score was independently related to e-GFR (r=0.328; p<0.001), and AER (r=0.138; p=0.017). Hemoglobin A1c (HbA1c) correlated with AER (r=0.148; p=0.007) but not with eGFR (r=0.041; p=0.310). Conclusions: Obese children and adolescents show early alterations in renal function, compared to normal weight peers, and they have similar renal profiles than age-matched peers with T1D.