Cardiorespiratory dynamics of type 2 diabetes mellitus: An extensive view of breathing and fitness challenges in a diabetes prevalent population

Abstract

Background: Diabetes mellitus (DM) is well known for related micro and macrovascular complications. Uncontrolled hyperglycemia in diabetes mellitus leads to endothelial dysfunction, inflammation, microvascular impairment, myocardial dysfunction, and skeletal muscle changes which affect multiple organ systems. This study was designed to take an extensive view of cardiorespiratory dynamics in patients with type 2 DM.

Methods: One hundred healthy controls (HC) and 100 DM patients were enrolled. We measured and compared the breathing patterns (spirometry), VO2 max levels (heart rate ratio method) and self-reported fitness level (international fitness scale) of individuals with and without diabetes. Data was analyzed in SPSS v.22 and GraphPad Prism v8.0.

Results: We observed restrictive spirometry patterns (FVC <80%) in 22% of DM as compared to 2% in HC (p = 0.021). There was low mean VO2 max in DM as compared to HC(32.03 ± 5.36 vs 41.91 ± 7.98 ml/kg/min; p value <0.001). When evaluating physical fitness on self-reported IFiS scale, 90% of the HC report average, good, or very good fitness levels. In contrast, only 45% of the DM shared this pattern, with a 53% proportion perceiving their fitness as poor or very poor (p = <0.05). Restrictive respiratory pattern, low VO2 max and fitness level were significantly associated with HbA1c and long-standing DM.

Conclusion: This study shows decreased pulmonary functions, decreased cardiorespiratory fitness (VO2 max) and IFiS scale variables in diabetic population as compared to healthy controls which are also associated with glycemic levels and long-standing DM. Screening for pulmonary functions can aid optimum management in this population.

Fig 1. Respiratory patterns among study participants DM vs HC (n = 200; DM = 100, HC = 100).

Cut off value for restrictive respiratory patterns, cut off FVC was <80% and for obstructive respiratory pattern, FEV₁/FVC <75–80% was considered. Mixed was defined as low FVC and FEV₁/FVC than predicted.

Fig 2. Comparison of VO₂ max (ml/kg/min) between the DM and HC.

(N = 200; DM = 100, HC = 100). A: Overall comparison of VO₂ max. B: Comparison of VO₂ max in age ≤50 years old in DM and HC. C: Comparison of VO2 max in age >50 years in DM and HC.

Fig 3. IFiS scale of fitness in study participants (N = 200).

A: Figure shows fitness level of Healthy controls (n = 100) on a self-reported 5-point Likert Internation fitness scale (IFiS); B: IFiS Scale of Fitness in DM (n = 100). Fitness levels were reported on a self-reported 5-point Likert Internation fitness scale (IFiS).