Phase Angle Evaluated by a Bioimpedance Analysis Is Closely Related to Diabetic Nephropathy and Peripheral Neuropathy in Patients with Type 2 Diabetes.

Introduction: The phase angle (PhA), calculated through bioimpedance analysis (BIA), is a measure of skeletal muscle quality and cellular integrity. This study aimed to explore the relationship between PhA and diabetic microangiopathy in patients with type 2 diabetes.

Methods: We conducted a cross-sectional analysis of 556 adult Japanese outpatients with type 2 diabetes who underwent body composition evaluation using BIA. Clinical characteristics, including diabetic microangiopathy (retinopathy, nephropathy, and neuropathy), were assessed for their association with PhA. Furthermore, in 23 patients who underwent a second BIA assessment, we examined the relationship between changes in PhA and glycated hemoglobin (HbA1c) levels longitudinally. Statistical methods employed included Wilcoxon's signed-rank test, regression analyses, and trend tests.

Results: PhA was significantly lower in patients with diabetic microangiopathy compared to those without it. It was positively correlated with the skeletal muscle mass index (SMI) and negatively correlated with the extracellular water-to-total body water ratio. Multiple regression analysis revealed that sex, age, nephropathy, peripheral neuropathy, hemoglobin, serum albumin, and low-density lipoprotein cholesterol levels were significant explanatory variables for PhA. In the longitudinal analysis, changes in HbA1c levels showed a significant negative correlation with changes in PhA, however, no association was observed between changes in HbA1c and changes in SMI.

Conclusions: PhA is significantly associated with age, malnutrition, and diabetic microvascular complications, and may provide insights into muscle and tissue health in patients with type 2 diabetes. Further research is required to examine causal relationships and explore potential interventions to preserve muscle quality in diabetic patients.