Independent Association of Phase Angle with Fasting Blood Glucose and Hemoglobin A1c in Korean Type 2 Diabetes Patients

Phase angle as an independent predictor of sarcopenia and glycemic control in older adults with type 2 diabetes: a cross-sectional observational study

Objectives

The global rise in type 2 diabetes mellitus (T2DM) poses challenges, particularly with the increasing burden of sarcopenia and poor glycemic control. Phase angle (PhA) is a promising biomarker for early detection and management of these conditions. This study aimed to evaluate PhA as an independent predictor of sarcopenia and glycemic control.

Methods

This cross-sectional study included older adults with T2DM hospitalized for diabetes education between April 2021 and March 2023. Measurements included PhA, muscle mass, body fat mass, grip strength, knee extension strength, physical function (Short Physical Performance Battery and 6-min walk distance), and glycemic control (fasting blood glucose and hemoglobin A1c [HbA1c]). Sarcopenia was defined as low muscle mass and physical function. Analyses included Pearson correlations, receiver operating characteristic curve analysis, and multivariate logistic regression.

Results

PhA was moderately correlated with muscle mass (r = 0.42, p < 0.001), grip strength (r = 0.43, p < 0.001), and body mass index (r = 0.27, p = 0.001), and inversely correlated with HbA1c (r = - 0.34, p < 0.001) and age (r = - 0.26, p = 0.003). PhA showed a strong predictive ability for sarcopenia (AUC = 0.83, 95% CI: 0.76-0.90, p < 0.001). Logistic regression indicated PhA as an independent predictor of sarcopenia (OR = 0.105, 95% CI: 0.031-0.353, p < 0.001) and glycemic control (OR = 0.380, 95% CI: 0.201-0.719, p = 0.003).

Conclusions

PhA is a non-invasive, practical tool for predicting sarcopenia and monitoring glycemic control. Routine integration of PhA could identify high-risk patients and guide interventions. Future research should validate its application in diverse settings.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-025-01590-z.

Exploring the significance of phase angle in diabetes management: a narrative review

Purpose

The phase angle is a mathematical concept representing the time relationship between two periodic waveforms, and has gained some importance for its potential clinical applications. The purpose of this review was to investigate the role of phase angle in diabetes mellitus.Studies have investigated the relationship between the phase angle and glycemic control, insulin resistance, and diabetes-related complications. Phase angle has demonstrated its potential as a prognostic marker for diabetic complications, enabling early identification and intervention. It might be beneficial for evaluating disease severity, monitoring treatment response, and predicting long-term results in diabetics.

Results and conclusion

Although the phase angle offers significant advantages, its clinical use in managing diabetes is still in its early stages, and there are certain issues that need to be resolved. Standardization of measurement techniques and interpretation criteria is essential to ensure consistency and comparability across studies and clinical settings. Investigating the role of phase angle in the treatment of diabetes provides significant knowledge about its potential as a non-invasive and informative parameter. Identifying the importance of phase angle in diabetes might help to improve risk stratification, treatment strategies, and patient outcomes. Additional research is required to determine its therapeutic value and discover the mechanisms underlying its association with diabetes and its complications.

Stronger associations of the phase angle than the TyG index with micro- and macrovascular complications in patients with type 2 diabetes

BACKGROUND

Identifying micro- and macrovascular damage through microalbuminuria and arterial stiffness is essential for preventing renal and cardiovascular complications in patients with type 2 diabetes mellitus (T2D). The primary goal of this research is to investigate the association of the phase angle (PA), triglyceride‒glucose (TyG) index, and homeostasis model assessment for insulin resistance (HOMA-IR) with microalbuminuria and arterial stiffness in patients with T2D.

METHODS

In this retrospective cross-sectional study, 938 participants with T2D were enrolled. The PA was calculated from bioelectrical impedance analysis. Logistic regression was used to analyze the association of PA, the TyG index and HOMA-IR with microalbuminuria (urinary albumin-to-creatinine ratio [UACR] > 30 mg/g using overnight urine) and increased arterial stiffness (brachial-ankle pulse wave velocity [baPWV] > 1400 cm/s), respectively. Potential nonlinear relationships between PA, the TyG index, and the prevalence of microalbuminuria and increased arterial stiffness were assessed via restricted cubic splines (RCS). Subgroup analysis evaluated the robustness of the association.

RESULTS

PA was inversely correlated with the UACR (r = -0.29, P < 0.001) and baPWV (r = -0.37, P < 0.001). Confounder-adjusted analyses revealed that the highest tertile of PA was significantly associated with lower prevalences of both microalbuminuria and increased arterial stiffness than the lowest tertile, with ORs of 0.305 and 0.467 and P trends < 0.001 and 0.017, respectively. Conversely, the highest TyG tertile was associated with increased prevalences of microalbuminuria and increased arterial stiffness, with ORs of 1.727 and 1.625, respectively, but the P trends were not statistically significant. There were no significant associations between HOMA-IR and microalbuminuria and increased arterial stiffness. RCS analysis further confirmed a significant linear relationship between PA and both vascular complications. Subgroup analyses consistently demonstrated the association between PA and microalbuminuria across all subgroups stratified by sex, age, BMI, HbA1c, and duration of diabetes (all P < 0.01).

CONCLUSIONS

Compared with the TyG index and HOMA-IR, PA is independently and more strongly associated with microalbuminuria and increased arterial stiffness in patients with T2D.

Exploring the association between phase angle of bioimpedance at 50 kHz and cardiovascular risk

BACKGROUND

Cardiovascular diseases are characterized by chronic inflammation, leading to increased inflammatory markers that can cause cell damage and death. Phase angle has emerged as a marker of cellular health. It is considered a prognostic factor in various acute and chronic conditions. However, few studies have examined its association with cardiovascular disease risk measures. This study aims to investigate the relationship between phase angle, the general Framingham risk score, and the HEARTS cardiovascular risk score.

METHODS

This cross-sectional study included a convenience sample of adult patients of 2 primary health care services. Phase angle was measured using multifrequency bioimpedance analysis at 50 kHz. The risk of cardiovascular events was calculated using the Framingham and HEARTS risk scores. Statistical analysis included generalized linear regression models, unadjusted and adjusted according to sex and age, to determine the association between scores, risk factors, and phase angle.

RESULTS

The study included 164 individuals with a mean age 52.2 (SD 17.9). According to the HEARTS score, low-risk patients had higher phase angle values than those with high or very high risk [ß = -0.57 (95% CI -0.95; -0.19), P = 0.003]. Framingham scores showed a trend toward significance for higher mean phase angle values in low-risk than high-risk patients [ß = -0.43 (95% CI -0.88 to 0.02), P = 0.06].

CONCLUSION

Phase angle values were lower in high and very high-risk patients than in low-risk patients, which shows that phase angle is a promising risk predictor for patients with cardiovascular diseases.

Phase Angle of Bioelectrical Impedance Analysis as an Indicator for Diabetic Polyneuropathy in Type 2 Diabetes Mellitus

CONTEXT

Due to the heterogenous clinical symptoms and deficits, the diagnosis of diabetic polyneuropathy (DPN) is still difficult in clinical routines, leading to increased morbidity and mortality.

OBJECTIVE

We studied the correlation of phase angle (PhA) of bioelectrical impedance analysis (BIA) with clinical, laboratory, and physical markers of DPN to evaluate PhA as a possible diagnostic method for DPN.

MATERIALS AND METHODS

In this cross-sectional observational study as part of the Heidelberg Study on Diabetes and Complications, we examined 104 healthy individuals and 205 patients with type 2 diabetes mellitus (T2D), among which 63 had DPN. The PhA was calculated from multifrequency BIA. Nerve conduction studies, quantitative sensory testing (QST) and diffusion-weighted magnetic resonance neurography to determine fractional anisotropy (FA) reflecting peripheral nerve integrity were performed.

RESULTS

T2D patients with DPN had lower PhA values (5.71 ± 0.10) compared to T2D patients without DPN (6.07 ± 0.08, P = .007, + 6.1%) and healthy controls (6.18 ± 0.08, P < .001, + 7.9%). Confounder-adjusted analyses showed correlations of the PhA with conduction velocities and amplitudes of the peroneal (β=.28; β=.31, P < .001) and tibial nerves (β=.28; β=.32, P < .001), Z-scores of QST (thermal detection β=.30, P < .05) and the FA (β=.60, P < .001). Receiver-operating characteristic analysis showed similar performance of PhA in comparison to the mentioned diagnostic methods.

CONCLUSION

The study shows that PhA is, in comparison to other test systems used, at least an equally good and much easier to handle investigator-independent marker for detection of DPN.

Association between preoperative phase angle and all-cause mortality after cardiovascular surgery: A retrospective cohort study

BACKGROUND

The importance of preoperative physical function assessment for post-operative intervention has been reported in older patients undergoing cardiovascular surgery. Phase angle (PhA), measured using bioelectrical impedance analysis, is an indicator of cellular health and integrity and is reported as a prognostic factor in several chronic diseases; however, its association with the long-term prognosis of cardiovascular surgery remains unclear. This study aimed to investigate the prognostic value of PhA for long-term mortality in patients undergoing cardiovascular surgery.

METHODS

This retrospective cohort study included consecutive patients who underwent elective cardiovascular surgery between October 2016 and March 2021 at Nagoya Heart Center, Japan. PhA was assessed using bioelectrical impedance analysis before surgery, and physical function measures (gait speed, grip strength and short physical performance battery [SPPB]) were measured synchronously. The association between PhA and all-cause mortality after discharge was assessed using Kaplan-Meier and multivariate Cox regression analyses. The incremental prognostic value of PhA was compared with other physical function measures using net reclassification improvement (NRI) and integrated discrimination improvement (IDI).

RESULTS

A total of 858 patients were included in the present analysis (mean age = 68.4 ± 11.9 years, 67.6% male). PhA positively correlated with body mass index (ρ = 0.38, P < 0.001), skeletal muscle mass index (ρ = 0.58, P < 0.001), usual gait speed (ρ = 0.44, P < 0.001), grip strength (ρ = 0.73, P < 0.001) and SPPB (ρ = 0.51, P < 0.001). The mean follow-up period, within which 44 (4.7%) died, was 908.9 ± 499.9 days for the entire cohort. Kaplan-Meier survival curves based on the PhA tertiles showed that higher PhA was associated with better survival (log-rank test, P < 0.001). The Cox regression analysis showed the independent association of PhA with mortality risk (hazard ratio: 0.91 per 0.1° increment; 95% confidence interval [CI]: 0.87-0.95; P < 0.001). The NRI and IDI showed significant improvements in predicting mortality after adding PhA to the clinical model consisting of age, sex and cardiac and renal function (NRI: 0.426, 95% CI: 0.124-0.729, P = 0.006; IDI: 0.037, 95% CI: 0.012-0.062, P = 0.003). The predictive model consisting of the clinical model and PhA was superior to the model consisting of the clinical model and each of the other physical function indicators (P < 0.05).

CONCLUSIONS

PhA correlated with physical function and independently predicted long-term mortality after cardiovascular surgery. The additive prognostic value of PhA compared with the other physical function measures suggests the clinical usefulness of preoperative PhA for risk stratification in planning post-operative treatment and rehabilitation.

Glycated hemoglobin (HbA1c) is independently associated with the bioelectrical impedance phase angle in junior sumo wrestlers: A pilot study

The study explores the relationship between phase angle (PhA), an indicator of cellular health, and metabolic health parameters among junior sumo wrestlers in Japan. Given the demanding lifestyle and high-energy diets of sumo wrestlers that predispose them to metabolic syndrome post-retirement, this study focuses on a younger cohort. The primary aim is to evaluate if PhA could serve as an early indicator of metabolic health issues within this unique demographic. A total of 14 sumo wrestlers aged 9-17 years were assessed to determine the relationship between PhA and various metabolic markers, including glycated hemoglobin (HbA1c), using a TANITA MC-780A-N body composition analyzer and standard blood tests. Bivariate regression analysis and Pearson's correlation revealed a negative relationship between PhA and HbA1c even after adjusting for age and weight (ß = -0.496, r2 = 0.776, r = -0.756, p = 0.004). The results indicate a significant negative relationship between PhA and HbA1c levels, suggesting that lower PhA values, which indicate poorer cellular integrity, are associated with higher HbA1c levels, signifying impaired glycemic control. These findings underscore the potential of PhA as a valuable biomarker for monitoring metabolic health in young sumo wrestlers, with implications for early intervention and management strategies.

Association of a Bioimpedance Profile with Optical Coherence Tomography Features in Diabetic Macular Edema

We examined the association between bioimpedance profiles and optical coherence tomography (OCT) features in patients with diabetic macular edema (DME). This cross-sectional study included 100 eyes of 100 patients with type 2 diabetes mellitus. The systemic fluid status was assessed using extracellular water-to-total body water ratio (ECW/TBW) and phase angle (PhA), which was measured using bioimpedance equipment. ECW/TBW was higher in the DR (diabetic retinopathy) with DME group than in the no DR and DR without DME groups (p = 0.007 and p = 0.047, respectively); however, no significant difference was observed between the no DR and DR without DME groups. The PhA values were significantly lower in the DR with DME group (5.45 ± 0.84) than in the no DR (6.69 ± 0.69) and DR without DME groups (6.05 ± 1.15) (p < 0.001, p = 0.032, respectively). The presence of multiple HRF (hyper-reflective foci) was associated with a significantly higher ECW/TBW (p = 0.001). In the group with the most significant HRF, PhA was lower than in those with none or moderate amounts of HRF (p < 0.05). Bioimpedance fluid profiles of patients with OCT features of DME suggest a connection between the overall systemic state, including fluid status and DME development. Further research is required to fully understand and utilize this information for effective clinical assessment and treatment planning.

Determinants of phase angle in Japanese patients with diabetes

Phase angle, obtained using bioelectrical impedance analysis, non-invasively reflects the whole-body cellular condition and nutritional status and may be helpful as a prognostic factor. Patients with diabetes had a smaller phase angle than healthy subjects. However, the clinical significance of phase angle has not yet been elucidated. Therefore, the purpose of this study was to clarify the relationship between phase angle and HbA1c in patients with diabetes and the clinical relevance of phase angle. A retrospective, multicenter, cross-sectional study was conducted with Japanese patients with diabetes. Body composition was determined with bioelectrical impedance analysis, and this was used to obtain phase angle. Phase angle was assessed in relation to clinical parameters, body composition parameters, and HbA1c levels. A total of 655 patients were enrolled (400 men and 255 women, aged 57.1 ± 14.8 years, body mass index 25.6 ± 5.2 kg/m2, HbA1c 8.1 ± 1.9%). Even in patients with diabetes, the phase angle was higher in men than in women and did not differ between the types of diabetes. Multiple regression analysis, performed with phase angle as the objective variable, and age, sex, diabetes type, HbA1c, albumin level, and body mass index as explanatory variables, revealed that phase angle was negatively affected by HbA1c (B = - 0.043, 95% Confidence interval: - 0.07 to - 0.02, p < 0.001). HbA1c, age, sex, albumin level, and body mass index were independent determinants of phase angle in participants with diabetes.

Association between lower phase angle and chronic kidney disease progression in type 2 diabetes patients

Introduction

Phase angle (PhA), derived from bioelectrical impedance analysis (BIA), is the angle of vector determined by the body's resistance and reactance. It indicates cellular integrity and hydration status. Though extracellular volume excess was associated with chronic kidney disease (CKD) progression, the association between PhA and CKD progression is unknown. Matrix metalloproteinase-2 (MMP-2) is a member of zinc-dependent endopeptidase family and promotes renal interstitial fibrosis. We investigated association between PhA and CKD progression, and whether the association was through MMP-2 in patients with type 2 diabetes mellitus (T2DM).

Method

We conducted a prospective study on 1,078 patients with T2DM (mean age 58.9±9.1 years). PhA was measured using BIA. CKD progression was defined as ≥25% decrease in estimated glomerular filtration rate (eGFR) from baseline with deterioration across eGFR categories. Multiplex immunoassay was used to quantitate MMP-2. We examined association between PhA and CKD progression using Cox proportional hazards model, adjusting for demographics, clinical parameters and medications.

Results

Over 8.6 years of follow-up, 43.7% of participants had CKD progression. Compared to tertile 3 PhA (higher level), tertiles 1 and 2 PhA were associated with higher hazards of CKD progression, with corresponding unadjusted hazard ratios (HRs) of 2.27 (95% confidence interval [CI] 1.80-2.87, P<0.001) and 1.57 (95% CI 1.24-2.01, P<0.001). The positive association between tertiles 1 and 2 PhA with CKD progression persisted in the fully adjusted model with corresponding HRs of 1.71 (95% CI 1.30-2.26, P<0.001) and 1.46 (95% CI 1.13-1.88, P=0.004). MMP-2 accounted for 14.7% of association between tertile 1 PhA and CKD progression.

Conclusion

Our findings revealed a previously unobserved association between BIA-derived lower PhA and CKD progression through MMP-2 in patients with T2DM.

Phase Angle Association with Dietary Habits and Metabolic Syndrome in Diabetic Hypertensive Patients: A Cross-Sectional Study

Phase angle (PhA) levels are often lower than normal because both disease-specific parameters and disease-related inflammatory status, metabolic syndrome (MetS) included, can affect PhA. Therefore, the aim of this cross-sectional study was to compare body composition, metabolic profile and dietary patterns of participants with arterial hypertension (AH), type 2 diabetes mellitus (T2DM) and MetS with regard to PhA values. A total of 208 participants were included, of whom 53.6% were males. For each participant, data about body composition and anthropometric parameters, clinical and laboratory parameters, as well as food frequency questionnaire (FFQ) and Mediterranean Diet Serving Score (MDSS) were obtained. MC-780 Multi Frequency Segmental Body Mass Analyzer (Tanita) was used to assess body composition. Furthermore, waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) were calculated. The results showed that 75 (36.06%) participants had low PhA values and 133 (63.94%) had high PhA values. Participants with higher PhA values had significantly higher body fat percentage (p = 0.04), fat-free mass (kg; p < 0.001), muscle mass (kg; p < 0.001), skeletal muscle mass (% and kg; p < 0.001), sarcopenic index (SMI; p < 0.001) and mid-upper arm circumference (MUAC; p = 0.04), as well as lower fat mass percentage (p = 0.04). Regarding food frequency consumption, significantly higher intakes of red meat (p = 0.003), poultry (p = 0.02) and fast food (p = 0.003) were noticed in participants with higher PhA values. Adherence to the Mediterranean Diet (MeDi) was exceptionally low in both groups of participants, with significantly higher fish intake noticed in participants with high PhA (p = 0.03). In conclusion, our results showed that body composition could be the indicator of PhA in MetS as well as overall low adherence to the MeDi principles. These findings highlight the importance of adequate nutritional strategies and novel approaches to maintaining optimal body composition and adopting proper eating habits within the framework of one’s disease.

The Extracellular Mass to Body Cell Mass Ratio as a Predictor of Mortality Risk in Hemodialysis Patients

The extracellular mass/body cell mass ratio (ECM/BCM ratio) is a novel indicator of nutritional and hydration status in hemodialysis (HD) patients. This study aimed to explore the ECM/BCM ratio as a predictor of mortality risk with nutritional-inflammatory markers in HD patients. A prospective observational study was conducted in 90 HD patients (male: 52.2%; DM: 25.60%). Clinical and biochemical parameters [serum albumin, serum C-reactive protein (s-CRP), interleukine-6 (IL-6)] were analysed and bioelectrical impedance analysis (BIA) was performed. Protein-energy wasting syndrome (PEW) was diagnosed using malnutrition-inflammation score (MIS). Based on BIA-derived measurements, the ECM/BCM ratio with a cut-off point of 1.20 was used as a PEW-fluid overload indicator. Comorbidity by Charlson index and hospital admissions were measured. Out of 90 HD patients followed up for 36 months, 20 patients (22.22%) died. PEW was observed in 24 survivors (34.28%) and all non-survivors. The ECM/BCM ratio was directly correlated with MIS, s-CRP, Charlson index and hospital admissions but was negatively correlated with phase angle and s-albumin (all, p < 0.001). Values of the ECM/BCM ratio ≥ 1.20 were associated with higher probability of all-cause mortality (p = 0.002). The ECM/BCM ratio ≥ 1.20, IL-6 ≥ 3.1 pg/mL, s-CRP and s-albumin ≥ 3.8 g/dL and Charlson index were significantly associated with all-cause mortality risk in multivariate adjusted analysis. This study demonstrates that the ECM/BCM ratio ≥ 1.20 as a nutritional marker and/or fluid overload indicator had a significant prognostic value of death risk in HD patients.