Phase angle as a predictive marker for very low-calorie diet efficacy in newly diagnosed type 2 diabetes mellitus

Phase angle (PhA), as a nutritional and metabolic indicator, can reflect the integrity of cell membranes and the functional status of cells, and may have a predictive effect on the prognosis of patients with newly diagnosed type 2 diabetes mellitus (T2DM) undergoing very low-calorie diet (VLCD). This study aims to investigate the predictive value of bioelectrical impedance PhA for assessing the therapeutic efficacy of VLCD in newly diagnosed T2DM patients. Additionally, we seek to explore whether PhA can serve as an early biomarker for metabolic improvements following VLCD intervention. A total of 223 newly diagnosed T2DM patients who received 9-day VLCD intervention (300-600 kcal/day) at the Xiamen Hospital of Traditional Chinese Medicine from July 2021 to December 2023 were enrolled. Baseline PhA was measured using multifrequency bioelectrical impedance analysis. Therapeutic efficacy was defined as posttreatment homeostasis model assessment of insulin resistance <2.5. Logistic regression and receiver operating characteristic curve analyses were performed. After VLCD intervention, 139 patients (62.3%) achieved the primary endpoint (homeostasis model assessment of insulin resistance < 2.5) with significant improvements in body weight and glycemic parameters. All participants completed the intervention with good compliance. No severe adverse events (including hypoglycemia or hepatorenal dysfunction) occurred. PhA was identified as an independent predictor (males: OR = 6.34, 95% CI = 3.025-13.291; females: OR = 1.82, 95% CI = 1.05-3.15). Receiver operating characteristic analysis showed optimal predictive accuracy in males (area under the curve = 0.728, P = .001; sensitivity 66.7%, specificity 76.5% at cutoff 6.45), but limited value in females (area under the curve = 0.586, P = .089). The reduction of PhA can be considered as an independent risk factor for the prognosis of newly diagnosed T2DM patients undergoing VLCD intervention and may serve as a predictive indicator for the efficacy of dietary restriction therapy in male patients with newly diagnosed T2DM, which has potential clinical application value.