Nonexercise Activity Thermogenesis is Significantly Lower in Type 2 Diabetic Patients With Mental Disorders Than in Those Without Mental Disorders: A Cross-sectional Study

Physical activity improves health in patients with mental disorders. Nonexercise activity thermogenesis (NEAT) represents energy expenditure due to daily physical activities other than volitional exercise. We aimed to evaluate NEAT in type 2 diabetic patients with and without accompanying mental disorders. Between September 2010 and September 2014, we studied 150 patients with type 2 diabetes, 50 of whom also had a diagnosis of mental disorder, such as schizophrenia or mood disorder. We evaluated their NEAT in structured interviews using a validated questionnaire, and investigated differences in NEAT score and metabolic parameters between patients with and without mental disorders. The NEAT score was significantly lower in patients with mental disorders than in those without (56.3 ± 9.9 vs 61.9 ± 12.1; P = 0.005). Patients with mental disorders had significantly higher triglyceride (184.5 ± 116.3 vs 146.4 ± 78.4 mg/dL; P = 0.02) and insulin levels (18.7 ± 20.1 vs 11.2 ± 8.5 μU/mL; P = 0.006), and significantly lower B-type natriuretic peptide (12.1 ± 13.3 vs 26.3 ± 24.8 pg/mL; P < 0.001) and brachial-ankle pulse wave velocity levels (1501 ± 371 vs 1699 ± 367 cm/s; P = 0.003) than patients without mental disorders. In patients with schizophrenia, specifically, NEAT showed a negative correlation with hemoglobin A1c levels (β = −0.493, P = 0.031), and a positive correlation with high-density lipoprotein cholesterol (β = 0.519, P = 0.023) and B-type natriuretic peptide levels (β = 0.583, P = 0.02). Our results suggest that NEAT may be beneficial for the management of obesity, insulin sensitivity, and lipid profiles in patients with mental disorders. Incorporating NEAT into interventions for type 2 diabetes in patients with mental disorders, especially schizophrenia, shows promise and warrants further investigation.