Among patients with type 2 diabetes undergoing bariatric surgery, adolescents have earlier resolution of elevated urinary albumin to creatinine ratio (UACR), compared to adults, reports a study in Kidney International.
The researchers analyzed 161 adolescents with severe obesity who underwent Roux-en-Y gastric bypass surgery. For comparison, they looked at a group of 396 adults undergoing gastric bypass—all with a reported history of obesity at age 18 or younger. Before gastric bypass, type 2 diabetes was present in 14% of the adolescents and 31% of the adults. For patients with preoperative type 2 diabetes, the adolescents and adults were similar in terms of preoperative weight, body mass index (BMI), and glycated hemoglobin. Among those without preoperative diabetes, the adolescents had higher weight, BMI, and insulin levels.
Renal outcomes 5 years after bariatric surgery were compared between age groups, focusing on spot UACR measurement and estimated glomerular filtration rate measured by serum creatinine and cystatin C. Analyses were stratified by the presence of preoperative type 2 diabetes.
Before surgery, the prevalence of elevated UACR was 22.5% in adolescents with type 2 diabetes, compared to 9.0% in diabetic adults. Follow-up data showed earlier improvement in elevated UACR in teens with preoperative diabetes compared to adults. In adolescents, adjusted prevalence of elevated UACR decreased from baseline to 1 year, remaining stable thereafter. In adults, adjusted prevalence of elevated UACR was stable from baseline to year 4, with a significant decline in year 5.
In contrast, there was no difference in UACR in response to gastric bypass between adolescents or adults without preoperative diabetes. Teens with preoperative type 2 diabetes had a higher prevalence of hyperfiltration (prevalence ratio 2.36), which persisted across the 5-year study period.
The study is the first to compare kidney outcomes after bariatric surgery in adolescents versus adults. “Adolescents with pre-operative type 2 diabetes experienced a more precipitous resolution of elevated UACR following gastric bypass compared to their adult counterparts,” the researchers write.
The age-related difference in UACR response after bariatric surgery adds to previous evidence that adolescents have “greater plasticity for comorbidity reversal.” Further studies with extended follow-up are needed to clarify the risks and benefits of bariatric surgery for severely obese adolescents, with and without type 2 diabetes [Bjornstad P, et al. Five year kidney outcomes of bariatric surgery differ in severely obese adolescents and adults with and without type 2 diabetes. Kidney Int 2020; DOI: https://doi.org/10.1016/j.kint.2020.01.016].