Comments on the Use of Visceral Adiposity Index to Predict Diabetes Remission in Low BMI Chinese Patients after Bariatric Surgery

Abstract

The recent paper by Ke et al. is an important study on the examination of the use of visceral adiposity index (VAI) for the prediction of diabetes remission in low body mass index (BMI) patients after bariatric surgery. This study shows interesting and promising preliminary trends that suggest VAI can be used as a threshold for the prediction of surgical efficacy beyond the current evidence [1]. Uncontrolled type 2 diabetes mellitus (T2DM) is a major risk factor for morbidity and mortality in obese and non-obese patients, making the study of treatment options and outcomes in both of these heterogeneous populations essential to providing high-quality medical care. The authors included patients with BMI < 35 kg/m and showed that the duration of diabetes, HbA1c, and VAI can predict remission of diabetes after bariatric surgery. They have discussed the limitations of their study including low sample size (87 patients) with only 13 patients with sleeve gastrectomy, retrospective nature of the study, and incomplete followup. In the study by Amato et al., the VAI metric was designed and examined. In addition to visceral fat dysfunction, VAI was showed to have an inverse correlation with insulin sensitivity whereas BMI and waist circumference did not. Furthermore, VAI was found to be positively correlated with many other components of metabolic syndrome including diabetes, high blood pressure, low HDL cholesterol, high triglyceride and LDL cholesterol, coronary heart disease, and risk of ischemic and thromboembolic events [2]. This result is important for consideration as it appears unclear what other factors contributing to T2DM are being potentially captured by VAI as well. While not disqualifying from the potential of VAI to be used as a predictor of remission of T2DM after bariatric surgery, it is important that careful attention is paid to ensuring all known predictors of T2DM remission after bariatric surgery are included in logistic regression and that VAI remains an independent predictor of remission in multivariate analysis. For future researches, all the known predictors associated with T2DM remission should be included in a regression model. Other potential factors to be included are “treatment with insulin” and “other medications for T2DM.” [3]. While weight loss in this low-BMI patient cohort was small, it may be worthwhile to include percent excess weight loss (%EWL) in the logistic regression since it is another predictor of T2DM remission post-surgically in obese patients [4]. Without the inclusion of all known predictive factors in regression analysis, the correlation of VAI with so many different components of metabolic syndrome may suggest that it is serving as a measurement of disease severity rather than an independent predictive factor in and of itself. As the authors mentioned, a CT scan or MRI for assessing visceral adiposity can be costly. However, the addition of CT or MRI for the measurement of central adiposity may be useful in future studies. Both CT and MRI have been useful and accurate in the quantification of visceral and hepatic fat distribution. This data would serve to not only correlate the VAI measure with truly measured adiposity but also may offer an opportunity to explore in what ways the inclusion of triglyceride and HDL improves VAI as a measure of adipose tissue dysfunction [5]. This is important because previous validation studies for VAI are mostly focused on the association of VAI with cardiovascular and metabolic outcomes. The results of this study cannot be generalized to all bariatric patients. The BMI of patients in this study was less than 35, with an average of 28.8 kg/m. Also, the study by Amato which defined the VAI was based on 315 non-obese healthy participants with BMI 20–30 [2]. Therefore, further studies in all BMI subgroups are needed for better generalization. * Zhamak Khorgami [email protected]