Association between reduced pulmonary diffusing capacity and cardiac autonomic dysfunction in Type 1 diabetes

Heart Rate Variability in Adults with Sickle Cell Anemia During a Multitasking Field Test

Background: The integrity of the autonomic nervous system (ANS) is essential for keeping physiological processes stable, even under stress. Since there is growing interest in heart rate variability (HRV) analysis for the noninvasive assessment of the ANS in sickle cell anemia (SCA) patients, we studied the behavior of the ANS in the presence of a stressor that simulates daily-life multitasking, the Glittre ADL test (GA-T). Objectives: To evaluate the involvement of the ANS using HRV in adults with SCA during the GA-T and to quantify the strength of the correlation of HRV with lung and muscle functions. Methods: In this cross-sectional study, 16 adults with SCA and 12 healthy controls without sickle cell disease underwent HRV assessment during the GA-T, pulmonary function tests (spirometry, diffusing capacity for carbon monoxide (DLCO), and respiratory muscle testing). Peripheral muscle function [handgrip strength (HGS) and quadriceps strength (QS)] were also measured. Results: Compared to the healthy controls, adults with SCA showed lower HRV, with worse parasympathetic modulation due to reductions in the following indices: the root-mean-square difference of successive normal iRRs (iRR) (RMSSD); the percentage of pairs of consecutive iRRs whose difference is > 50 m (pNN50); the high-frequency component of heart rate variability (HF); and the standard deviation of instantaneous beat-to-beat variability (SD1) (P < 0.001 for all). Compared to healthy controls, individuals with SCA showed greater sympathovagal imbalance (higher ratio between low-frequency and HF components) and lower complexity of the ANS (lower approximate entropy). The GA-T time was correlated with parasympathetic activity indices: RMSSD (rs = -0.650, P < 0.01); pNN50 (rs = -0.932, P < 0.0001), HF (rs = -0.579, P < 0.01), and SD1 (rs = -0.814, P < 0.0001). Correlations between parasympathetic activity indices and DLCO, HGS, and QS measures were also significant. Conclusions: Adults with SCA have low HRV, with low parasympathetic activity, sympathovagal imbalance, and abnormal ANS complexity. In addition, lower HRV is associated with longer GA-T time, greater impairment of pulmonary diffusion, and greater muscle strength dysfunction.

Effect of Subcutaneous Insulin on Spirometric Maneuvers in Patients with Type 1 Diabetes: A Case-Control Study

In order to compare spirometric maneuvers in adults according to the presence of type 1 diabetes, a case-control study including 75 patients with type 1 diabetes and 75 controls matched by sex, age, and body mass index were designed. In addition, 75 patients with type 1 diabetes were added to examine the potential the impact of subcutaneous insulin therapy on pulmonary function. Lung function measurements were assessed according to the global initiative for chronic obstructive lung disease guidelines. Basal insulin included long-acting insulin analogues and the delivered background insulin in patients with pump therapy. Bolus insulin included rapid-acting insulin analogues and the delivered insulin to cover postprandial hyperglycemias. Patients with type 1 diabetes showed lower spirometric values in comparison to the control group, together with a higher prevalence of forced expiratory volume in the first second (FEV1) <80% (10.7% vs. 2.7%, p = 0.044) and restrictive ventilatory pattern (10.7% vs. 0%, p = 0.006) The dose of basal insulin (U/kg/day) showed a negative correlation with forced vital capacity (FVC) (r = −0.205, p = 0.012) and FEV1 (r = −0.182, p = 0.026). The optimal cut-off value for identifying patients with a restrictive spirometric pattern was 0.5 U/kg/day of basal insulin. Additionally, basal insulin (U/kg/day) independently predicted the presence of both a restrictive spirometric pattern (OR = 77.1 (3.2 to 1816.6), p = 0.007) and an abnormal FEV1 (OR = 29.9 (1.5 to 562.8), p = 0.023). In patients with type 1 diabetes, higher basal insulin dosage seems to be related with an impairment of pulmonary function.

Diabetic lung disease: fact or fiction?

Diabetes mellitus is a chronic, progressive, incompletely understood metabolic disorder whose prevalence has been increasing steadily worldwide. Even though little attention has been paid to lung disorders in the context of diabetes, its prevalence has recently been challenged by newer studies of disease development. In this review, we summarize and discuss the role of diabetes mellitus involved in the progression of pulmonary diseases, with the main focus on pulmonary fibrosis, which represents a chronic and progressive disease with high mortality and limited therapeutic options.

Impact of diabetes mellitus on functional exercise capacity and pulmonary functions in patients with diabetes and healthy persons

BACKGROUND

Chronic diabetic complications may afflict all organ tissues, including those of the respiratory system. The six-minute walk test (6MWT) is an alternative and widely used method of assessing functional capacity and is simple to perform. However, to our knowledge, the impact of diabetes mellitus on 6MWT performance has not been investigated previously. This research aimed to compare the functional exercise capacity and pulmonary functions in patients with diabetes and in healthy persons.

METHODS

The study included 131 participants: 64 patients with type 1 and 2 diabetes mellitus (DM) and 67 healthy participants (CG). All of the participants were nonsmoking and did not have pulmonary disorders that affected the pulmonary function tests or 6MWT. Metabolic parameters and biochemical markers of inflammation were assessed. Full lung function tests and a 6MWT were performed.

RESULTS

In the DM group, the walking distance was 109 m shorter than that in the CG (P < 0.001). Moreover, compared to the CG, the DM group showed lower values of forced expiratory volume in one second (FEV1 (l) 3.6 vs. 2.8, P < 0.001) and total lung capacity (TLC (l) 6.6 vs. 5.6, P < 0.001), as well as a decrease in diffusion capacity (DLCO (mmol/min/kPa), 10.0 vs. 8.6, P < 0.001).

CONCLUSIONS

The 6MWT is a valuable test that complements the assessment of daily physical capacity in patients with diabetes, irrespective of type. Pulmonary function and the capacity for physical exertion varied between patients with diabetes mellitus and the healthy participants in the CG.

The diabetic lung--a new target organ?

Several abnormalities of the respiratory function have been reported in patients with type 1 and type 2 diabetes. These abnormalities concern lung volume, pulmonary diffusing capacity, control of ventilation, bronchomotor tone, and neuroadrenergic bronchial innervation. Many hypotheses have emerged, and characteristic histological changes have been described in the "diabetic lung", which could explain this abnormal respiratory function. Given the specific abnormalities in diabetic patients, the lung could thus be considered as a target organ in diabetes. Although the practical implications of these functional changes are mild, the presence of an associated acute or chronic pulmonary and/or cardiac disease could determine severe respiratory derangements in diabetic patients. Another clinical consequence of the pulmonary involvement in diabetes is the accelerated decline in respiratory function. The rate of decline in respiratory function in diabetics has been found to be two-to-three times faster than in normal non-smoking subjects, as reported in longitudinal studies. This finding, together with the presence of anatomical and biological changes similar to those described in the aging lung, indicates that the "diabetic lung" could even be considered a model of accelerated aging. This review describes and analyses the current insight into the relationship of diabetes and lung disease, and suggests intensifying research into the lung as a possible target organ in diabetes.

Cough reflex sensitivity in adolescents with diabetic autonomic neuropathy

Objective

Diabetic autonomic neuropathy (DAN) is one of the chronic complications of diabetes mellitus which can involve one or more organ systems. DAN without apparent symptoms is more often in childhood and adolescence. While heart rate variability (HRV) and Ewing's battery of cardiovascular tests are regarded as a gold standard for the diagnosis of DAN, the examination of cough reflex sensitivity (CRS) is another possibility. The aim of this study was to compare HRV and CRS in children with diabetes mellitus.

Materials and methods

Sixty one patients (37 girls, 24 boys) aged 15-19 suffering from diabetes mellitus type 1 completed the study. Based on HRV, patients were divided into 2 groups - with DAN (n = 25) and without DAN (n = 32), 4 patients were excluded because of ambiguous results. CRS was studied in each patient by inhalation of gradually increasing concentration of capsaicin.

Results

Subjects with DAN required a significantly higher concentration of capsaicin needed to evoke 2 coughs (median 625 μmol/l, IQR 68.4-625.0 μmol/l vs. median 29.3 μmol/l, IQR 9.8-156.3 μmol/l, P < 0.001) and 5 coughs (median 2500.0 μmol/l, IQR 1250.0-2500.0 μmol/l vs. median 312.5 μmol/l, IQR 117.2-625.0 μmol/l, P < 0.001) compared with those without DAN. Moreover, a strong negative correlation between HRV and CRS was established.

Conclusion

Diabetes mellitus lowers the cough response. Cough reflex sensitivity appears to be another sensitive method for the evaluation of DAN in diabetes.