Maximum BMI Predicts Advanced Diabetic Complications Before T2D Onset

Maximum body mass index (BMI) before the onset of type 2 diabetes (MBBO) is independently associated with complications of the disease but BMI on admission is not, according to a study in BMJ Open Diabetes Research & Care.

Researchers retrospectively reviewed data from 1304 consecutive patients who were admitted to a hospital in Japan for treatment of poor glycemic control from August 2010 to June 2017. Investigators sought to evaluate whether MBBO or BMI could predict progressive diabetic retinopathy or diabetic nephropathy in patients with type 2 diabetes (T2D).

Univariate and multivariate analyses were performed by logistic regression models to predict outcomes of advanced retinopathy or nephropathy. In the multivariate analyses, to assess the effect of BMI, MBBO, and age at MBBO on prediction, a model was developed using a stepwise method with backward selection for all variables that excluded them. Cross-validation was used to determine whether adding these factors to the model would improve prediction accuracy.

A total of 435 participants (262 men and 173 women) had a mean (±SD) age of 63 (51~72) years and a mean age at T2D diagnosis of 50 (42~60) years. Patients had a median glycated hemoglobin (HbA_1c) of 8.5% (70 mmol/mol), and most had poor glycemic control.

Univariate logistic regression analysis indicated that MBBO was associated with advanced retinopathy, while BMI on admission was not. However, univariate analysis suggested that MBBO and BMI on admission could be associated with advanced nephropathy.

Researchers also performed a multiple logistic regression that included MBBO. The P value of this analysis was .041, indicating a significant association between MBBO and advanced retinopathy. For advanced nephropathy, the P value of the analysis including MBBO was 0.0018, indicating a significant association between MBBO and advanced nephropathy.

In a comparison of the area under the curve (AUC) for the 4 models yielded by cross-validation, for advanced diabetic retinopathy the AUCs ranged from 0.701 to 0.723. For advanced nephropathy, the AUCs ranged from 0.812 to 0.831. In a comparison of AUCs among models, high MBBO was independently associated with advanced retinopathy and nephropathy after adjusting for other variables, while BMI on admission was not.

Study limitations include the retrospective, cross-sectional, observational design. Also, many patients whose maximum BMI was reached after the diagnosis of T2D were excluded, and the study authors did not evaluate medications for hypertension, dyslipidemia, or hyperuricemia.

“At the time of the diagnosis of diabetes mellitus, MBBO would enable us to predict the progress of diabetic complications, and this prediction would lead to more careful support and medical treatment,” the researchers concluded.

Reference

Ozawa H, Fukui K, Komukai S, et al. Maximum body mass index before onset of type 2 diabetes is independently associated with advanced diabetic complications. BMJ Open Diabetes Res Care. 2021;9:e002466. doi:10.1136/bmjdrc-2021-002466