Study of BMI and ESRD suggests obesity may provide a health benefit when it comes to end-stage renal disease.
Type 2 diabetes and obesity are a significant health problem worldwide. It is known that type 2 diabetes (T2D) is one of the leading causes of renal failure, including chronic kidney disease and end-stage renal disease (ESRD). However, some data shows that there is an inverse association between obesity and chronic kidney disease or ESRD. There are limited studies that compare the effect of obesity on the risk of ESRD in patients with and without T2D. Therefore, Yang-Hyun Kim et al. sought to evaluate the association between BMI and the risk of ESRD according to the glycemic status of the participants. The researchers also examined the association between BMI and the risk of ESRD according to the presence of T2D in sustained BMI groups, because high variability of BMI was associated with the development of ESRD in the general population.
Researchers monitored 9,969,848 Korean participants older than 20 years of age. The latter underwent a National Health Insurance Service health checkup in 2009 from baseline to the date of diagnosis of ESRD during a follow-up period of ∼8.2 years. Participants were monitored until December 2017. Those subjects who had missing data, type 1 diabetes, or had a history of renal disease were excluded from the study. Obesity was categorized by World Health Organization recommendations for Asian populations, and glycemic status was categorized into the following five groups: normal, impaired fasting glucose, newly diagnosed diabetes, and diabetes.
From the participants included in the study, there were 34,094 individuals with newly diagnosed ESRD. Diabetes was diagnosed in 868,241 patients (8.71%): 293,163 as newly diagnosed; 299,389 as <5 years diabetes; and 275,689 as >5 years diabetes.
The hazard ratio of ESRD increased as BMI decreased. The hazard ratio was highest in the underweight group (HR 1.602; 95% CI 1.504–1.706) and lowest in the obesity stage 1 group (HR 0.627; 95% CI 0.606– 0.649), after adjusting for all baseline covariates (age, sex, smoking, alcohol drinking, regular exercise, income, T2D, hypertension, dyslipidemia, chronic kidney disease [CKD], glucose, and waist circumference [WC]. In the underweight group, participants with T2D had a higher hazard ration of ESRD (HR 1.733) compared with those without T2D (HR 1.535) after adjusting for all covariates. However, in the overweight, obesity stage I and obesity stage II groups, participants without T2D had a higher hazard ratio of ESRD compared with those with T2D, after adjusting for all covariates (HR 0.75, 0. 7, and 0.809 in those without T2D and 0.679, 0.525, and 0.46 in those with T2D, respectively) (all P for interaction,0.001).
The researchers also analyzed the incidence ratio (per 1,000) and hazard ratio of ESRD by BMI category, stratified based on fasting glucose and diabetes duration. In the group with normal fasting glucose, the incidence ratio was highest in the obesity stage II group (IR 0.315). However, in the groups with impaired fasting glucose, the incidence ratio was the highest in the underweight group and increased with worsening glycemic status. In the groups with impaired fasting glucose, the hazard ratio of the underweight group increased with worsening glycemic status.
Also, the researchers examined the risk of ESRD in sustained BMI groups according to the presence of T2D. A total of 325,0627 participants were in sustained BMI groups: 112,279 as underweight, 1,402,030 as healthy weight, 671,920 as overweight, 960,973 as obesity stage I, and 103,425 as obesity stage II. The hazard ratio for ESRD was highest in subjects with sustained underweight status regardless of the presence of T2D. In the group without T2D, the hazard ratio ESRD showed a reverse J-curve. However, the hazard–ratio of ESRD in the group with T2D decreased as BMI increased.
The results from this study showed that the risk of ESRD is increased in patients with obesity and underweight, and underweight patients showed a more increased hazard ratio of ESRD according to glycemic status in the Korean participants. There was also a strong association between lower BMI and the risk of ESRD observed according to T2D status and the diabetes duration. Many studies have shown that higher BMI was associated with an increased risk of kidney disease, but the finding from this study is inconsistent with those previously published studies.
- The results of this nationwide cohort study provide evidence that low BMI is associated with a higher risk of ESRD development according to the T2D status and the duration of T2D.
- The findings persisted in the groups with sustained BMI.
- This study focusses on the nation of Korea; a more extensive study over a longer time may be able to provide more definitive data of the risk of ESRD in different ethnicities.
Kim, Yang-Hyun, et al. “Underweight Increases the Risk of ESRD for T2D in Korean Population: Data from the National Health Insurance Service Health Checkups 2009-2017.” Diabetes Care, American Diabetes Association, March 18. 2020, care.diabetesjournals.org/content/early/2020/03/12/dc19-2095.
Chardae Whitner, 2020 PharmD. Candidate, Lake Erie College of Osteopathic Medicine