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RESEARCH PRODUCT

Bioimpedance phase angle indicates catabolism in Type 2 diabetes

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Aims Body cell mass is directly proportional to the bioimpedance phase-angle which is an indicator of the amount of electrical charge that cell membranes can hold and is an index of cellular health and function. To evaluate whether the bioimpedance phase angle is relevant for indicating catabolism in people with diabetes and whether it discriminates between people with diabetes receiving different types of therapy. Methods A cross-sectional study was performed in 182 people with Type 2 diabetes and 107 age- and BMI-matched control subjects. The phase angle was measured at 5, 50 and 100 kHz using multifrequency bioimpedance analysis. The phase angles were compared among different diabetes therapy groups (untreated patients with diabetes, patients receiving oral antidiabetic drugs and patients receiving insulin therapy). Results The phase angle at 100 kHz strongly correlated with total body potassium (r = 0.70, P = 0.001), and was therefore a good indicator of body cell mass. The phase angle at 100 kHz discriminated more strongly between patients with Type 2 diabetes and control subjects than did the phase angle at 50 kHz. Compared with control subjects, patients with Type 2 diabetes had a smaller phase angle at 100 kHz (men: 5.2° vs. 4.5°, P < 0.0001; women: 4.8° vs. 4.2°, P < 0.0001) and a smaller phase angle at 50 kHz (men: 5.9° vs. 5.3°, P < 0.0001; women: 5.4° vs. 4.8°, P = 0.0001), but a larger phase angle at 5 kHz (men: 2.0° vs. 2.6°, P = 0.0001; women: 2.3° vs. 3.0°, P = 0.00001). Phase angle ratios better discriminated between patients and control subjects than phase angles alone (phase angle at 5 kHz/ phase angle at 50 kHz ratio, P = 1.51 × 10−16; phase angle at 5kHz/phase angle at 100 kHz ratio, P = 2.13 × 10−15). No differences were found among phase angles in the different therapy groups. In patients with diabetes, the phase angle at 50 kHz and the phase angle at 100 kHz correlated inversely with duration of disease (men: P = 0.026, P = 0.016; women: only phase angle at 100 kHz, P = 0.003) and with HbA1c concentration (men: P = 0.010, P = 0.001; women: P = 0.007, P = 0.043). Conclusions The phase angle at 100 kHz is a promising measurement for assessing catabolic state in people with diabetes.