Reduced vital capacity in insulin-dependent diabetes

Type 1 diabetes contributes to combined pulmonary fibrosis and emphysema in male alpha 1 antitrypsin deficient mice

Type 1 diabetes (T1D) is a metabolic disease characterized by hyperglycemia and can affect multiple organs, leading to life-threatening complications. Increased prevalence of pulmonary disease is observed in T1D patients, and diabetes is a leading cause of comorbidity in several lung pathologies. A deficiency of alpha-1 antitrypsin (AAT) can lead to the development of emphysema. Decreased AAT plasma concentrations and anti-protease activity are documented in T1D patients. The objective of this study was to determine whether T1D exacerbates the progression of lung damage in AAT deficiency. First, pulmonary function testing (PFT) and histopathological changes in the lungs of C57BL/6J streptozotocin (STZ)-induced T1D mice were investigated 3 and 6 months after the onset of hyperglycemia. PFT demonstrated a restrictive pulmonary pattern in the lungs of STZ-injected mice, along with upregulation of mRNA expression of pro-fibrotic markers Acta2, Ccn2, and Fn1. Increased collagen deposition was observed 6 months after the onset of hyperglycemia. To study the effect of T1D on the progression of lung damage in AAT deficiency background, C57BL/6J AAT knockout (KO) mice were used. Control and STZ-challenged AAT KO mice did not show significant changes in lung function 3 months after the onset of hyperglycemia. However, histological examination of the lung demonstrated increased collagen accumulation and alveolar space enlargement in STZ-induced AAT KO mice. AAT pretreatment on TGF-β-stimulated primary lung fibroblasts reduced mRNA expression of pro-fibrotic markers ACTA2, CCN2, and FN1. Induction of T1D in AAT deficiency leads to a combined pulmonary fibrosis and emphysema (CPFE) phenotype in male mice.

The Diabetic Lung: Insights into Pulmonary Changes in Children and Adolescents with Type 1 Diabetes

Historically, the lung was not listed and recognized as a major target organ of diabetic injury. The first evidence of diabetic lung involvement was published fifty years ago, with a study conducted in a population of young adults affected by type 1 diabetes (T1D). In recent years, there has been mounting evidence showing that the lung is a target organ of diabetic injury since the beginning of the disease—at the pediatric age. The deeply branched vascularization of the lungs and the abundance of connective tissue, indeed, make them vulnerable to the effects of hyperglycemia, in a way similar to other organs affected by microvascular complications. In this review, we focus on pulmonary function impairment in children and adolescents affected by T1D. We also cover controversial aspects regarding available studies and future perspectives in this field.

Baseline characteristics and risk factors for short-term outcomes in 132 COVID-19 patients with diabetes in Wuhan China: A retrospective study

AIMS

To investigate the clinical characteristics, laboratory findings and high- resolution CT (HRCT) features and to explore the risk factors for in-hospital death and complications of coronavirus disease 2019 (COVID-19) patients with diabetes.

METHODS

From Dec 31, 2019, to Apr 5, 2020, a total of 132 laboratory-confirmed COVID-19 patients with diabetes from two hospitals were retrospectively included in our study. Clinical, laboratory and chest CT data were analyzed and compared between the two groups with an admission glucose level of ≤11 mmol/L (group 1) and >11 mmol/L (group 2). Logistic regression analyses were used to identify the risk factors associated with in-hospital death and complications.

RESULTS

Of 132 patients, 15 died in hospital and 113 were discharged. Patients in group 2 were more likely to require intensive care unit care (21.4% vs. 9.2%), to develop acute respiratory distress syndrome (ARDS) (23.2% vs. 9.2%) and acute cardiac injury (12.5% vs. 1.3%), and had a higher death rate (19.6% vs. 5.3%) than group 1. In the multivariable analysis, patients with admission glucose of >11 mmol/l had an increased risk of death (OR: 7.629, 95%CI: 1.391-37.984) and in-hospital complications (OR: 3.232, 95%CI: 1.393-7.498). Admission d-dimer of ≥1.5 μg/mL (OR: 6.645, 95%CI: 1.212-36.444) and HRCT score of ≥10 (OR: 7.792, 95%CI: 2.195-28.958) were associated with increased odds of in-hospital death and complications, respectively.

CONCLUSIONS

In COVID-19 patients with diabetes, poorly-controlled blood glucose (>11 mmol/L) may be associated with poor outcomes. Admission hyperglycemia, elevated d-dimer and high HRCT score are potential risk factors for adverse outcomes and death.

Cystic Fibrosis-Related Diabetes

Cystic fibrosis (CF) is the most common autosomal recessive disorder in Caucasian populations. Individuals with CF have seen significant increases in life expectancy in the last 60 years. As a result, previously rare complications are now coming to light. The most common of these is cystic fibrosis-related diabetes (CFRD), which affects 40-50% of CF adults. CFRD significantly impacts the pulmonary function and longevity of CF patients, yet a lack of consensus on the best methods to diagnose and treat CFRD remains. We begin by reviewing our understanding of the pathogenesis of CFRD, as emerging evidence shows the cystic fibrosis transmembrane conductance regulator (CFTR) also has important roles in the release of insulin and glucagon and in the protection of β cells from oxidative stress. We then discuss how current recommended methods of CFRD diagnosis are not appropriate, as continuous glucose monitoring becomes more effective, practical, and cost-effective. Finally, we evaluate emerging treatments which have narrowed the mortality gap within the CF patient group. In the future, pharmacological potentiators and correctors directly targeting CFTR show huge promise for both CFRD and the wider CF patient groups.

Evaluation of pulmonary function changes in children with type 1 diabetes mellitus in Upper Egypt

BACKGROUND

Diabetes mellitus is a leading cause of morbidity and mortality among children across the world and is responsible for a growing proportion of global healthcare expenditure. However, limited data are available on lung dysfunction in children with diabetes.

AIM

The aim of this study was to evaluate the pulmonary function changes in children with type 1 diabetes mellitus (T1DM).

METHODS

We studied 60 children with T1DM (mean age 10.5 ± 2.32 years; disease duration 2.45 ± 0.6 years, and 50 healthy control children (mean age 9.9 ± 2.5 years). Spirometry was performed for all individuals to measure forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC ratio, and peak expiratory flow rate (PEFR). Glycemic control was assessed on the basis of glycated hemoglobin (HbA1c), with HbA1c values <8% considered to indicate good glycemic control, and HbA1c values ⩾8% to indicate poor control.

RESULTS

There was significant reduction in all spirometeric parameters in diabetic children in comparison with healthy control children. Children with poor glycemic control had significant impairment in lung functions compared with those with good glycemic control.

CONCLUSIONS

T1DM in children leads to impairment of lung functions and this impairment increases with poor glycemic control.

Pulmonary function in children with type 1 diabetes mellitus

AIM

To assess lung function in children and adolescents with type 1 diabetes mellitus (T1DM).

PATIENTS AND METHODS

We conducted a case-control study of 100 patients with T1DM [median age 13 (10.6-14.7), 44% men, 23% prepubertal, and all nonsmokers] and 77 controls. None had evidence of lung disease or any other comorbidity. We performed pulmonary function tests, including spirometry [forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), and FEV₁/FVC ratio], plethysmography [total lung capacity (TLC), residual volume (RV), RV/TLC ratio, and airway resistance (Raw)], and diffusing capacity of carbon monoxide in the lung (TLCO), alveolar volume (AV), and TLCO/AV ratio. The duration of diabetes, degree of metabolic control, insulin dose, and presence of diabetic complications were registered. The χ²-test and analysis of variance were used to compare categorical and quantitative variables, respectively.

RESULTS

The duration of diabetes was 6.2±3.8 years with a median HbA₁c of 7.08±0.4%. FEV₁/FVC ratio was found to be significantly higher in patients with TIDM than in controls. Patients with diabetes also had a nonsignificant trend towards lower FVC, FEV₁, Raw, and TLCO, and higher RV, TLC, and RV/TLC than controls. There were no differences in pulmonary function based on duration of disease or metabolic control. We found differences in pulmonary evaluation when pubertal stage was analyzed.

CONCLUSIONS

The lung is functionally involved in children with T1DM. Pubertal development stage influences the evaluation of lung function.

Pulmonary functions in patients with diabetes mellitus

Background:

A reduction in lung capacity has been reported previously among diabetics. According to WHO estimates, Pakistan is currently eighth in the prevalence of diabetes mellitus (DM) and will become fourth by the year 2025 with over 15 million individuals. This study was designed to see the impairment of lung functions on spirometry in DM patients.

Objective:

Our aim was to investigate the pulmonary functions tests of Pakistani patients with DM.

Materials and Methods:

Between January to July 2004, 128 subjects who were never-smokers and had no acute or chronic pulmonary disease were recruited. Sixty-four of these subjects had DM and 64 were healthy matched controls. All underwent screening with detailed history, anthropometry, lipid profile, and spirometric measurements at the Aga Khan University Hospital, Karachi, Pakistan.

Results:

The mean age of diabetics and matched control were 54.3±9 and 54.0±8 (P<0.87) years, respectively. Diabetes patients showed a significant reduction in the forced vital capacity (FVC) [mean difference (95% CI) – 0.36 (–0.64, –0.07) P<0.01], forced expiratory volume in one second (FEV₁) [– 0.25(–0.50, –0.003) P<0.04], and slow vital capacity (SVC) [– 0.28(–0.54, –0.01) P<0.04], relative to nondiabetic controls. There was no significant difference noted in the forced expiratory ratio and maximum mid-expiratory flow between the groups. There was also a significant higher level of triglycerides noted among diabetics (P<0.001).

Conclusion:

Diabetic patients showed impaired lung function independent of smoking. This reduced lung function is likely to be a chronic complication of diabetes mellitus.

Pulmonary complications in diabetes mellitus

Clear decrements in lung function have been reported in patients with diabetes over the past two decades, and many reports have suggested plausible pathophysiological mechanisms. However, there are no reports of functional limitations of activities of daily living ascribable to pulmonary disease in patients with diabetes. This review attempts to summarize the available information from the present literature, to describe the nature of the lung dysfunction in diabetes and the emerging clinical implications of such dysfunction.

Effect of duration of disease on ventilatory function in an ethnic Saudi group of diabetic patients

BACKGROUND

Diabetes mellitus is a leading cause of illness and death across the world and is responsible for a growing proportion of global health care expenditures. The present study was designed to observe the effect of diabetes mellitus on lung function in patients with diabetes belonging to a specific ethnic group, namely Saudis.

METHOD

In this study, a group of 47 apparently healthy volunteer male Saudi patients with diabetes was randomly selected. Their ages ranged from 20 to 70 years. The patients were matched with another group of 50 healthy male control subjects in terms of age, height, weight, ethnicity, and socioeconomic status. Both groups met exclusion criteria as per standard. Spirometry was performed with an electronic spirometer (Schiller AT-2 Plus, Switzerland), and results were compared by a Student's t test.

RESULTS

Subjects with diabetes showed a significant reduction in forced vital capacity (FVC) and forced expiratory volume in the first second (FEV(1)) relative to their matched controls. However, there were no significant differences in the forced expiratory ratio (FEV(1)/FVC%) and the middle half of the FVC (FEF(25-75%)) between the groups. We observed a significantly negative correlation between duration of disease and pulmonary function, as measured by FEV(1) (r = 0.258, p = 0.04), FVC (r = 0.282, p = 0.28), and the middle half of the FVC (FEF(25-75%)) (r = 0.321, p = 0.014).

CONCLUSIONS

Pulmonary function in a specific ethnic group of patients with diabetes was impaired as evidenced by a decrease in FVC and FEV(1) compared to pulmonary function in matched controls. Stratification of results by years of disease revealed a significant correlation between duration of disease and a decline in pulmonary function.

Pulmonary Function in Patients With Type 1 Diabetes Before and After Simultaneous Pancreas and Kidney Transplantation

INTRODUCTION

Pulmonary function is impaired in type 1 diabetes mellitus and is associated with the quality of metabolic control. Correction of chronic hyperglycemia by pancreas transplantation may ameliorate pulmonary function.

METHODS

Lung volume and diffusing capacity were measured in 75 uremic patients with type 1 diabetes and a long diabetes duration waiting for a simultaneous kidney and pancreas transplantation (SPK). In addition 85 patients after SPK and 20 patients after kidney transplantation alone (KA) were investigated. In a subgroup of 30 patients, data before and after SPK were available for prospective analysis.

RESULTS

Reduced lung volume and diffusing capacity were found in type 1 diabetic patients before transplantation. Nearly all parameters of pulmonary function improved after SPK and KA. A significant change was found for forced expiratory volume at 1 sec (FEV1) and FEV1/forced vital capacity (FVC) (Tiffenau index). A significant amelioration of diffusing capacity was only found in the SPK group but not in the KA group. The prospective investigation revealed significant improvements of pulmonary function after SPK: FEV1 (P=0.001), FVC, (P=0,006), Tiffenau index (P=0.03), and Hb-corrected diffusing capacity (carbon monoxide transfer factor, TCO), P=0.03; transfer coefficient (KCO=TCO corrected for alveolar volume), P=0.01.

CONCLUSION

Simultaneous pancreas and kidney transplantation is able to attain long-term normoglycemia and to improve pulmonary function in uremic type 1 diabetic patients.

The challenges of chronic obstructive pulmonary diseases (COPD)--a perspective

Chronic Obstructive Pulmonary Disease (COPD) is an inflammatory disease, primarily caused by cigarette smoke, which will soon become the third leading cause of death globally. Despite the importance of the problem, our real understanding of the biological underpinnings of COPD remains incomplete. Consequently, our first-line therapies, while helpful, are not yet as effective as they need to be. In this review, we will focus on these challenges and more, including the role of impaired tissue repair and adaptive immunity in disease pathogenesis, determining who may be at risk, describing COPD phenotypes and potential biomarkers. New ideas for chronic disease management and prevention of exacerbations will also be discussed. While much remains to be accomplished, meeting these challenges will bring rewards because what we learn will have implications for the understanding and treatment of chronic inflammatory diseases beyond COPD.

Diffusing capacity for carbon monoxide in children with type 1 diabetes

AIMS/HYPOTHESIS

Few data are available on lung dysfunction in children with diabetes. We studied the association of pulmonary function variables (flows, volumes and alveolar capillary diffusion) with disease-related variables in children with type 1 diabetes mellitus.

METHODS

We studied 39 children with type 1 diabetes (mean age 10.9+/-2.6 years, disease duration 3.6+/-2.4 years, insulin.kg(-1).day(-1) 0.77+/-0.31) and 30 healthy control children (mean age 10.4+/-3.0 years). Pulmonary function tests included spirometry, N(2) wash-out and the single-breath diffusing capacity for carbon monoxide (DL(CO)) corrected for the alveolar volume (DL(CO)/V(A)). Glycaemic control was assessed on the basis of HbA(1)c, with HbA(1)c values of 8% or less considered to indicate good glycaemic control, and HbA(1)c values of 8% or more considered to indicate poor control.

RESULTS

Children with poor glycaemic control had comparable percentage values for predicted flows and volumes but lower DL(CO)/V(A) values than children with good glycaemic control and healthy control children (86.7+/-12.6 vs 99.8+/-18.4 and 102.0+/-15.7; p<0.05). The predicted DL(CO)/V(A) percentages correlated with HbA(1)c levels (r=-0.39, p=0.013). A multiple regression analysis (stepwise model) controlling for HbA(1)c levels and other disease-related variables (age of disease onset, disease duration, daily insulin dose/kg, sex) identified HbA(1)c levels as the sole predictor of DL(CO)/V(A) in percent.

CONCLUSIONS/INTERPRETATION

In children with type 1 diabetes, the diffusing capacity diminishes early in childhood and is associated with poor metabolic control. Although low DL(CO)/V(A) levels in these children probably reflect pulmonary microangiopathy induced by type 1 diabetes, other factors presumably influencing CO diffusion capacity measurements (e.g. a left shift in HbA(1)c resulting in high O(2) binding and low CO binding) could explain the apparent capillary and alveolar basal membrane dysfunction.

beta-hydroxybutyrate induces acute pulmonary endothelial dysfunction in rabbits

The authors examined the effects of high ketone body and glucose concentrations on endothelial cell (EC) function in perfused rabbit lungs. beta-Hydroxybutyrate (beta OHB), at 5 mM, decreased endothelial angiotensin-converting enzyme (eACE) activity, whereas 25 mM glucose (HG), 1 mM beta OHB, or 10 mM acetoacetate (AcAc) did not. Dry to wet weight ratios were also reduced in lungs perfused with 5 mM beta OHB, but not with AcAc. beta OHB, at 5 mM, caused massive hemorrhage and interstitial and alveolar neutrophil infiltration; AcAc only produced engorgement of septal capillaries. Thus, pulmonary EC dysfunction occurs in rabbit lungs acutely perfused with beta OHB, but not with AcAc or glucose.

Lung function in children with diabetes mellitus

A cross-sectional study design was undertaken to assess pulmonary function in children with insulin-dependent diabetes mellitus (IDDM), and to establish if there is any relationship with diabetic factors and complications. Thirty-eight children (10 +/- 1.8 years) with IDDM and without clinical or radiological evidence of lung involvement, and 41 healthy age-matched reference subjects, underwent a pulmonary function study. Thirteen (34%) of 38 subjects with IDDM were studied at the onset of their disease. Adjusted values expressed as SD score of forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV(1)), and the transfer factor for carbon monoxide (TLCO) were found to be significantly lower than in controls (-0.54 +/- 0.87 vs. 0.40 +/- 1.10, P = 0.0008; -0.11 +/- 0.96 vs. 0.52 +/- 1.07, P = 0.01; -1.60 +/- 1.07 vs. -0.57 +/- 1.28, P = 0.001, respectively). These differences also existed in the group investigated at onset of diabetes. Residual volume (RV) and RV/total lung capacity ratio (RV/TLC) were significantly higher in the whole group of patients with IDDM than in controls (-0.20 +/- 0.83 vs. -0.80 +/- 0.88, P = 0.003; and 26 +/- 6.2 vs. 21 +/- 5.0, P = 0.0002, respectively). Seventeen patients (45%) had abnormal pulmonary function (SD score, less than -1.64): 16 subjects had reduced TLCO, 4 had reduced FVC, and in 3 of the 17, both functional indices were abnormal. There was no significant relationship between pulmonary function indices and diabetic factors or complications. The only significant association was between abnormal TLCO and females (P = 0.03), suggesting that sex may be a predisposing factor for the development of pulmonary complications. This study supports the view that the lung is functionally involved in children with IDDM early on in the course of the disease.

Lung function abnormalities in children with type I diabetes

Recent developments in intrabronchial administration of insulin raise lung function in patients with type I diabetes as important issue. Several studies in adults report abnormalities of lung function of these patients. The aim of this study was to investigate lung function in children with type I diabetes. Twenty-seven children with type I diabetes performed measurement of airway obstruction (forced flow-volume curves), lung volumes and airway resistance (bodyplethysmography) and of pulmonary carbon monoxide diffusion capacity Mean age (+/- SD) of the children was 12.8 +/- 5 years. Mean time between the detection of type I diabetes and the lung function tests was 5.5 years with a variation from I to 17 years. The total airway resistance (Raw) was significantly higher compared to the reference values (P < 0.001). The other lung function parameters were not significantly different from reference values (P > 0.05). In this relatively small study no relationship between lung function abnormalities and age, the duration of disease or level of HbA1c was observed. Our data show that increase of airway resistance do occur in children withtype I diabetes. Progressive abnormalities in lung function might interfere with the promising results of treatment with intrabronchial administration of insulin.

Pulmonary function in patients with diabetes mellitus

BACKGROUND

Pulmonary complications of diabetes mellitus have been poorly characterized. Although some authors have reported normal pulmonary function, others found abnormalities in lung volumes, pulmonary mechanics, and diffusing capacity.

SUBJECTS AND METHODS

We studied pulmonary function in a group of patients with diabetes using a combined cardiopulmonary exercise test. Twenty-seven patients with diabetes aged 48 +/- 13 years participated in the study.

RESULTS

Overall, forced vital capacity, forced expiratory volume in 1 second, and forced expiratory flow, midexpiratory phase, were within the predicted values, but the residual volume/total lung capacity ratio was slightly elevated. Comparison by diabetes type showed nonsignificant differences in forced expiratory volume in 1 second and forced expiratory flow, midexpiratory phase. Residual volume/total lung capacity ratio was significantly elevated in type 1 patients compared with type 2. Carbon monoxide diffusion capacity (DLCO) was normal in both groups. There was no correlation between the results on pulmonary function test and duration of disease, presence of microangiopathy, or glycemic control. The DLCO was significantly lower in patients with microangiopathic changes, but not when DLCO was corrected for alveolar volume. On the cardiopulmonary exercise test, maximal workload, maximum oxygen uptake, and maximal heart rate were less than predicted, whereas anaerobic threshold and ventilatory reserve were normal. No significant differences were noted in diabetes type, and there was no correlation between parameters of cardiopulmonary exercise test and the other variables.

CONCLUSION

Spirometric values are preserved in patients with diabetes mellitus, and there are no defects in diffusing capacity. Cardiovascular factors may account for impaired physical performance. There is no need for routine screening of pulmonary function among diabetic patients.

The efficacy of aldose reductase inhibitors in the management of diabetic complications. Comparison with intensive insulin treatment and pancreatic transplantation

Recently, aldose reductase inhibitors (ARIs) have been registered in several countries for the improvement of glycaemic control. However, their efficacy is still controversial. ARIs inhibit the enhanced flux of glucose through the polyol pathway. As such, they can never be more effective than normoglycaemia, and so their potential benefits and limitations should be considered relative to the effects of prolonged euglycaemia. The clinical effects of ARIs can be put into perspective by assessing the effects of improved glycaemic control attained in randomised trials of intensive insulin treatment [such as the Diabetes Control and Complications Trial (DCCT)] and after pancreatic transplantation. Although direct comparison of these 3 interventions is hampered by differences in patient populations, duration and methods of follow-up and in the potency of ARIs, the effects of these 3 metabolic interventions and their course in time appear remarkably similar. For neuropathy, all 3 interventions induce an increase in average motor nerve conduction velocity of approximately 1 m/sec during the first months of treatment. At the same time, improvement of painful symptoms may occur. These changes probably largely represent a metabolic amelioration of the condition of the nerves. Around the second year of treatment with all 3 forms of metabolic improvement, an acceleration of nerve conduction of a similar magnitude occurs, with signs of structural nerve regeneration and some sensory recuperation. Experience with ARIs in nephropathy is still limited, but similar improvements in glomerular filtration rate and, less consistently, in urinary albumin excretion were found during short term normoglycaemia produced by all 3 forms of treatment. Comparison of a small number of studies, however, shows differences between intensive insulin regimens, pancreatic transplantation and ARIs in effects on retinopathy. Retinopathy often temporarily deteriorates in the early phases of improved glycaemic control, but this is not noted with ARIs. New microaneurysm formation was slightly reduced in a single long term study with the ARI sorbinil, but the preventive effects on the overall levels of retinopathy seemed less strong than in normoglycaemia trials of similar duration. However, the pharmacodynamic effects on inhibiting the polyol pathway differ among ARIs, and the half-life of the inhibiting effect of sorbinil may have been too short for a complete reduction of polyol pathway activity. The trials of prolonged intensive insulin therapy and pancreatic transplantation have demonstrated that very strict metabolic control must be maintained continuously for many years before a significant reduction of complications can be demonstrated.(ABSTRACT TRUNCATED AT 400 WORDS)

Mechanical load on the inspiratory muscles during exercise hyperpnea in patients with type 1 (insulin-dependent) diabetes mellitus

The aim of this study was to evaluate the difference between Type 1 (insulin-dependent) diabetic patients and healthy control subjects regarding inspiratory muscle load during exercise hypernea. For this purpose an incremental progressive exercise test on a cycle ergometer was performed by 36 Type 1 diabetic patients and 40 healthy subjects. In order to determine the mechanical load on the inspiratory muscles breath by breath, we selected the following two parameters, which represent the pressure generated by the inspiratory muscles as well as the duration and velocity of their contraction: (1) the oesophageal tension time index, which is the product of the duty cycle (ratio of inspiratory time to total breath cycle duration) and the mean oesophageal pressure expressed as a percentage of the maximal oesophageal pressure and (2) the mean oesophageal pressure change per time unit during the inspiratory phase of each breathing manoeuver, which is expressed as a fraction of the subject's maximal oesophageal pressure. Comparison of the two groups revealed that at similar levels of ventilation the mechanical load on the inspiratory muscles was significantly higher in the Type 1 diabetic patients than in the control subjects. When the loading was stopped the maximal ventilation was lower in the patients. Nevertheless, they reported a degree of respiratory effort sensation comparable to the control group, which seems to have been caused by an increase of the mechanical load on the ventilatory muscles.

Pulmonary gas exchange and oxygen uptake during exercise in patients with type 1 diabetes mellitus

In order to investigate pulmonary gas exchange and cardiopulmonary performance in Type 1 diabetes, 36 patients underwent a progressive incremental exercise test on a cycle ergometer. Cardiopulmonary variables were measured, and arterial blood gases determined on samples obtained from an indwelling catheter in the radial artery. The results were compared with those from 40 control subjects. In the patients, the maximum power (Wmax) and maximum oxygen uptake (VO2max) were lower than in the control subjects (Wmax 186 +/- 52 (+/- SD) vs 233 +/- 48 W, p less than 0.05; VO2max 2.56 +/- 0.71 vs 3.17 + 0.77 l min-1, p less than 0.05). At comparable levels of power output, however, no significant abnormality was observed in the difference between alveolar and arterial oxygen pressure (P(A-a)O2), and the ratio of physiological dead space to tidal volume (VD/VT ratio). These data indicate that in Type 1 diabetic patients, despite their reduced maximum oxygen uptake, gas transfer during exercise is not limited and thus does not contribute to the impairment of exercise capacity.

Relationship between diabetes control and pulmonary function in insulin-dependent diabetes mellitus

PURPOSE

To evaluate the effect of different levels of glycemic control on the pulmonary function of subjects with type I insulin-dependent diabetes mellitus.

PATIENTS AND METHODS

Eighteen subjects with type I insulin-dependent diabetes mellitus with no history or physical findings of respiratory disease. Patients were given insulin therapy with a standard twice-daily insulin injection regimen (standard treatment group) or a subcutaneous insulin infusion device (insulin pump) (intensive treatment group). Glycosylated hemoglobin (HbA1c) levels were determined at quarterly intervals in both groups of patients (standard treatment group, n = 10; intensive treatment group, n = 8). Pulmonary function and diffusing capacity for carbon monoxide (DLCO) were measured after 6 years of continuous follow-up.

RESULTS

The average HbA1c in the standard treatment group was significantly higher than that of the intensive treatment group throughout the 6 years of follow-up (p less than 0.001). The forced vital capacity of the standard treatment group was 85 +/- 3% of predicted as compared with 106 +/- 4% of predicted in the intensive treatment group (p less than 0.001). The DLCO was also significantly diminished in the standard treatment group as compared with that in the intensive treatment group (65 +/- 2% versus 87 +/- 4% of predicted) (p less than 0.001).

CONCLUSION

These data confirm previous reports of abnormal respiratory function in subjects with insulin-dependent diabetes mellitus and suggest that long-term near-normoglycemia may be beneficial in preventing the deterioration of pulmonary function associated with diabetes mellitus.

Diabetes mellitus associated with cystic fibrosis

The prevalence of overt diabetes mellitus and carbohydrate intolerance was studied in 448 patients with cystic fibrosis (CF). Insulin-dependent diabetes (IDDM) developed in 7.6% of patients (13 male and 21 female). Survival was significantly lower (P less than 0.01) in the IDDM-CF group, with fewer than 25% surviving to age 30 years, whereas nearly 60% of the nondiabetic CF population reached this age. A significant deterioration in CF clinical status, based on NIH score, became apparent 2 years before onset of overt IDDM (P less than 0.05 at 2 years prior, P less than 0.01 at IDDM diagnosis). Total glycosylated hemoglobin (HbA1) was significantly (P less than 0.001) higher for the total CF population (7.3% +/- 1.2%) than for the general non-CF population (6.5% +/- 0.7%), and in the IDDM-CF group (P less than 0.05) compared with normoglycemic CF control patients. Female patients had a higher mean HbA1 after 12 years of age than their male counterparts did (P less than 0.02). HBA1 did not predict the development of IDDM, but there was a weak inverse relationship between HbA1 and both NIH clinical score (r = -0.41, P less than 0.02) and standard pulmonary function tests (forced vital capacity, r = -0.25, P less than 0.01) in the general CF population. Therefore, impaired carbohydrate tolerance in CF is associated with progressive clinical deterioration.