Clinical Significance of the Maximum Body Mass Index Before Onset of Type 2 Diabetes for Predicting Beta-Cell Function

Harutoshi Ozawa; Kenji Fukui; Sho Komukai; Yoshiya Hosokawa; Yukari Fujita; Takekazu Kimura; Ayumi Tokunaga; Junji Kozawa; Hiromi Iwahashi; Iichiro Shimomura

Disclosures

J Endo Soc. 2020;4(4) 

In This Article

Abstract and Introduction

Abstract

Objective: This study aimed to clarify the clinical significance of the maximum body mass index (BMI) before the onset of type 2 diabetes (MBBO) for predicting pancreatic beta-cell function.

Methods: This was a cross-sectional observational study. Of 1304 consecutively admitted patients with type 2 diabetes, we enrolled 410 patients satisfying the criteria in this study. The correlations between the C-peptide index (CPI), which is one of the parameters that reflects beta-cell function, and various clinical parameters, including MBBO and duration of diabetes, were analyzed in multiple linear regression analyses.

Results: The analyses revealed that MBBO was correlated with CPI independently after adjustment for age, sex, HbA1c, and duration of diabetes. When we divided the subjects into three subgroups by MBBO (MBBO < 25 kg/m2; 25 kg/m2 ≤ MBBO < 30 kg/m2; MBBO ≥ 30 kg/m2), CPI was negatively correlated with duration of diabetes in each subgroup, while the rates of CPI based on the duration of diabetes were not different among the three MBBO subgroups. In contrast, the declining rates of CPI were higher in the BMI ≥ 25 kg/m2 group on admission than in the BMI < 25 kg/m2 group on admission.

Conclusions: MBBO may be an independent factor correlating with beta-cell function and may predict insulin secretion capacity at diagnosis, but it does not seem to affect the rate of decline in insulin secretion capacity after diagnosis. It is important to preserve beta-cell function by decreasing a patient's BMI during treatment after diagnosis regardless of MBBO.

Introduction

Type 2 diabetes is characterized by both insulin resistance and beta-cell dysfunction.[1] Insulin resistance is mainly caused by overweight or visceral fat accumulation generated from patient lifestyles,[2,3] while beta-cell function in individuals is determined by genetic factors.[4] It has been reported that the insulin secretion capacity of patients with type 2 diabetes declines progressively with the duration of diabetes,[5] and some previous reports have suggested that a high body mass index (BMI) during treatment for diabetes is associated with a high rate of decline in insulin secretion capacity in the patient.[6,7]

In contrast, in prediabetes, beta cells increase insulin secretion in response to insulin resistance to maintain plasma glucose at a normal level;[1] thus, the degree of insulin resistance could also represent the insulin secretion capacity. Since BMI is the major determinant of insulin resistance,[8] BMI should also be an indicator of beta-cell function in individuals with prediabetes.[9] Physicians often inquire regarding the maximum BMI before type 2 diabetes onset, but the clinical significance of this parameter is not necessarily clear. Although several studies have described the relationship between the BMI of patients with type 2 diabetes mellitus and the rate of decline in beta-cell function, it seems difficult to use the BMI of patients with type 2 diabetes mellitus as an indicator of beta-cell function. This is because their BMI would be affected by medications for the treatment of glycemic control. Considering that BMI should be an indicator of beta-cell function in patients with prediabetes, the maximum BMI before onset of diabetes (MBBO) might reflect the maximum beta-cell function that the patient had ever possessed. Thus, we thought that this parameter, MBBO, could express the potential function of beta cells in patients. However, few clinical studies have been conducted to evaluate whether MBBO is associated with insulin secretion capacity.

The purpose of this study was to examine whether MBBO can act as an indicator of beta-cell function in patients with type 2 diabetes mellitus. We enrolled diabetic patients admitted to our hospital and analyzed the correlations between their MBBO and various clinical parameters, including insulin secretion capacity, in a multiple regression analysis. We also investigated whether MBBO may be an independent factor predicting the beta-cell function of the patient and whether it might affect the rate of decline in insulin secretion capacity after diagnosis during the treatment of diabetes.

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