Subclinical Inflammation Is Associated With Reductions in Muscle Oxygenation, Exercise Capacity and Quality of Life in Adults With Type 2 Diabetes.

Objectives: Exercise capacity is related to both morbidity and mortality in patients with type 2 diabetes (T2DM). The aim of this study was to investigate the relationship between subclinical inflammation level, exercise capacity, muscle oxygenation and quality of life in T2DM.

Methods: This study includes 28 patients with T2DM (mean age, 51.5±5.0 years; male-to-female ratio, 6:22). Exercise capacity was evaluated using an incremental symptom-limited maximal exercise test on a bicycle ergometer. Muscle oxygenation was investigated using a wearable lactate-measuring device. Diabetes-specific quality of life was assessed using the Diabetes Quality of Life Questionnaire (DQOL). Subclinical inflammation was assessed using C-reactive protein (CRP) levels.

Results: CRP level was negatively correlated with peak workload during the test (r=-0.588, p=0.002), muscle oxygenation (r=-0.465, p=0.019) and the psychological impact of treatment subscale of the DQOL (r=-0.540, p=0.017), and positively correlated with body mass index (r=0.519, p=0.008), waist circumference (r=0.426, p=0.038) and fat percentage (r=0.573, p=0.004). There was no correlation between CRP and fasting blood glucose or glycated hemoglobin level (p>0.05). Peak workload was inversely related to fat percentage (r=-0.467, p=0.016) and the DQOL worry about the future impact of diabetes subscale (r=-0.501, p=0.021).

Conclusions: In our study, subclinical inflammation negatively affected muscle oxygenation, exercise capacity and quality of life independently of glycemic indicators. Our findings suggest that the degree of glycemic control is insufficient to explain lower exercise capacity. Further studies are needed to investigate subclinical inflammation-reducing interventions in T2DM.