Pulmonary complications of type 1 (insulin-dependent) diabetic patients

Respiratory function in uncomplicated type 1 diabetes: Blunted during exercise even though normal at rest!

AIMS

Type 1 diabetes is associated with a substantially increased risk of impaired lung function, which may impair aerobic fitness. We therefore aimed to examine the ventilatory response during maximal exercise and the pulmonary diffusion capacity function at rest in individuals with uncomplicated type 1 diabetes.

METHODS

In all, 17 adults with type 1 diabetes free from micro-macrovascular complications (glycated haemoglobin: 8.0 ± 1.3%), and 17 non-diabetic adults, carefully matched to the type 1 diabetes group according to gender, age, level of physical activity and body composition, participated in our study. Lung function was assessed by spirometry and measurements of the combined diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) at rest. Subjects performed a maximal exercise test during which the respiratory parameters were measured.

RESULTS

At rest, DLCO (30.4 ± 6.1 ml min^-1  mmHg^-1 vs. 31.4 ± 5.7 ml min^-1 mmHg^-1 , respectively, p = 0.2), its determinants Dm (membrane diffusion capacity) and Vc (pulmonary capillary volume) were comparable among type 1 diabetes and control groups, respectively. Nevertheless, spirometry parameters (forced vital capacity = 4.9 ± 1.0 L vs. 5.5 ± 1.0 L, p < 0.05; forced expiratory volume 1 = 4.0 ± 0.7 L vs. 4.3 ± 0.7 L, p < 0.05) were lower in individuals with type 1 diabetes, although in the predicted normal range. During exercise, ventilatory response to exercise was different between the two groups: tidal volume was lower in type 1 diabetes vs. individuals without diabetes (p < 0.05). Type 1 diabetes showed a reduced VO_2max (34.7 ± 6.8 vs. 37.9 ± 6.3, respectively, p = 0.04) in comparison to healthy subjects.

CONCLUSIONS

Individuals with uncomplicated type 1 diabetes display normal alveolar-capillary diffusion capacity and at rest, while their forced vital capacity, tidal volumes and VO₂ are reduced during maximal exercise.

Mechanisms Linking COPD to Type 1 and 2 Diabetes Mellitus: Is There a Relationship between Diabetes and COPD?

Chronic obstructive pulmonary disease (COPD) patients frequently suffer from multiple comorbidities, resulting in poor outcomes for these patients. Diabetes is observed at a higher frequency in COPD patients than in the general population. Both type 1 and 2 diabetes mellitus are associated with pulmonary complications, and similar therapeutic strategies are proposed to treat these conditions. Epidemiological studies and disease models have increased our knowledge of these clinical associations. Several recent genome-wide association studies have identified positive genetic correlations between lung function and obesity, possibly due to alterations in genes linked to cell proliferation; embryo, skeletal, and tissue development; and regulation of gene expression. These studies suggest that genetic predisposition, in addition to weight gain, can influence lung function. Cigarette smoke exposure can also influence the differential methylation of CpG sites in genes linked to diabetes and COPD, and smoke-related single nucleotide polymorphisms are associated with resting heart rate and coronary artery disease. Despite the vast literature on clinical disease association, little direct mechanistic evidence is currently available demonstrating that either disease influences the progression of the other, but common pharmacological approaches could slow the progression of these diseases. Here, we review the clinical and scientific literature to discuss whether mechanisms beyond preexisting conditions, lifestyle, and weight gain contribute to the development of COPD associated with diabetes. Specifically, we outline environmental and genetic confounders linked with these diseases.

Altered Expiratory Flow Dynamics at Peak Exercise in Adult Men With Well-Controlled Type 1 Diabetes

Type 1 diabetes may, in time, cause lung dysfunction including airflow limitation. We hypothesized that ventilatory flow morphology during a cardiopulmonary exercise test (CPET) would be altered in adult men with well-controlled type 1 diabetes. Thirteen men with type 1 diabetes [glycated hemoglobin A1c 59 (9) mmol/mol or 7.5 (0.8)%, duration of diabetes 12 (9) years, and age 33.9 (6.6) years] without diagnosed diabetes-related complications and 13 healthy male controls [age 37.2 (8.6) years] underwent CPET on a cycle ergometer (40 W increments every 3 min until volitional fatigue). We used a principal component analysis based method to quantify ventilatory flow dynamics throughout the CPET protocol. Last minute of each increment, peak exercise, and recovery were examined using linear mixed models, which accounted for relative peak oxygen uptake and minute ventilation. The type 1 diabetes participants had lower expiratory peak flow (P = 0.008) and attenuated slope from expiration onset to expiratory peak flow (P = 0.012) at peak exercise when compared with the healthy controls. Instead, during submaximal exercise and recovery, the type 1 diabetes participants possessed similar ventilatory flow dynamics to that of the healthy controls. In conclusion, men with relatively well-controlled type 1 diabetes and without clinical evidence of diabetes-related complications exhibited attenuated expiratory flow at peak exercise independently of peak oxygen uptake and minute ventilation. This study demonstrates that acute exercise reveals alterations in ventilatory function in men with type 1 diabetes but not until peak exercise.

When kidneys and lungs suffer together

A significant interaction between kidneys and lungs has been shown in physiological and pathological conditions. The two organs can both be targets of the same systemic disease (eg., some vasculitides). Moreover, loss of normal function of either of them can induce direct and indirect dysregulation of the other one. Subjects suffering from COPD may have systemic inflammation, hypoxemia, endothelial dysfunction, increased sympathetic activation and increased aortic stiffness. As well as the exposure to nicotine, all the foresaid factors can induce a microvascular damage, albuminuria, and a worsening of renal function. Renal failure in COPD can be unrecognized since elderly and frail patients may have normal serum creatinine concentration. Lungs and kidneys participate in maintaining the acid-base balance. Compensatory role of the lungs rapidly expresses through an increase or reduction of ventilation. Renal compensation usually requires a few days as it is achieved through changes in bicarbonate reabsorption. Chronic kidney disease and end-stage renal diseases increase the risk of pneumonia. Vaccination against Streptococcus pneumonia and seasonal influenza is recommended for these patients. Vaccines against the last very virulent H1N1 influenza A strain are also available and effective. Acute lung injury and acute kidney injury are frequent complications in critical illnesses, associated with high morbidity and mortality. The concomitant failure of kidneys and lungs implies a multidisciplinary approach, both in terms of diagnostic processes and therapeutic management.

Increased risk of respiratory diseases in adults with Type 1 and Type 2 diabetes

AIMS

Diabetes is linked with decreases in lung elasticity and in capacity to transfer carbon monoxide. Systemic inflammation, a common concern with diabetes, may contribute to airflow obstruction. We examined the association of self-reported diabetes with self-reported respiratory diseases (RDs) among 53,146 adults from the C8 Health Project.

METHODS

Participants were categorized into three groups: Type 1 (T1D, n = 781), Type 2 (T2D, n = 4277), or no diabetes (n = 48,088). ORs (95% CIs) for the association of diabetes with four RDs were computed: emphysema, chronic obstructive pulmonary disease (COPD), chronic bronchitis (CB), and asthma. Covariates controlled for were age, sex, estimated glomerular filtration rate, C-reactive protein, smoking history, BMI, and perfluorooctonaoic acid (C8).

RESULTS

RDs were present in 26%, 21% and 13% of persons with T1D, T2D, and no diabetes, respectively. In multivariable analyses, persons with T1D were 62% more likely to have any RD (OR: 1.62, CI: (1.36-1.93)), while those with T2D were 1.3 times as likely (OR: 1.26, CI: 1.15-1.37)). Compared to those without diabetes, in those with T1D and T2D diabetes respectively, ORs (CIs) for COPD were 1.89 (1.38-2.57), 1.45 (1.23-1.71), asthma: 1.51 (1.21-1.87), 1.38 (1.24-1.53), CB: 1.96 (1.57-2.45), 1.35 (1.20-1.52) and emphysema: 1.25 (0.85-1.82), 1.31 (1.10-1.56). Population attributable risks for any RDs associated with a history of smoking were 19%, 30%, and 26% for those with Type 1, Type 2, and no diabetes respectively.

CONCLUSIONS

Diabetes, more so in T1D, appears to increase RD risk. Smoking is an important risk factor, but not as informative in Type 1 diabetes.

Global Autorecognition and Activation of Complement by Mannan-Binding Lectin in a Mouse Model of Type 1 Diabetes

Increasing evidence links mannan-binding lectin (MBL) to late vascular complications of diabetes. MBL is a complement-activating pattern recognition molecule of the innate immune system that can mediate an inflammation response through activation of the lectin pathway. In two recent animal studies, we have shown that autoreactivity of MBL is increased in the kidney in diabetic nephropathy. We hypothesize that long-term exposure to uncontrolled high blood glucose in diabetes may mediate formation of neoepitopes in several tissues and that MBL is able to recognize these structures and thus activate the lectin pathway. To test this hypothesis, we induced diabetes by injection of low-dose streptozotocin in MBL double-knockout (MBL/DKO) mice. Development of diabetes was followed by measurements of blood glucose and urine albumin-to-creatinine ratio. Fluorophore-labelled recombinant MBL was injected intravenously in diabetic and nondiabetic mice followed by ex vivo imaging of several organs. We observed that MBL accumulated in the heart, liver, brain, lung, pancreas, and intestines of diabetic mice. We furthermore detected increased systemic complement activation after administration of MBL, thus indicating MBL-mediated systemic complement activation in these animals. These new findings indicate a global role of MBL during late diabetes-mediated vascular complications in various tissues.

Type 1 Diabetes Duration Decreases Pulmonary Diffusing Capacity during Exercise

BACKGROUND

Diabetes damages peripheral tissues; however, its effects on the lung are less known. Lung diffusing capacity (DLCO) is influenced by alveolar-capillary membrane conductance (DM) and pulmonary capillary blood volume (VC), both of which are reduced in adults with type 1 diabetes (T1D).

OBJECTIVE

We sought to determine if diabetes duration affects DLCO, DM, VC, and cardiac output (Q).

METHODS

24 T1D patients (10.7-52.8 years) and 24 non-diabetic controls were recruited and had DLCO, DM, VC, and Q measured at rest and during exercise (40, 70 and 90% VO2max).

RESULTS

When stratified into two groups based on age (young, <20.6 years old), there were no significant differences in DLCO, DM, VC, or Q (all of which were normalized to body surface area [BSA]) in the young group or in the old group. When stratified by diabetes duration (short duration, 0.33-8.9 years vs. long duration, 9.6-28 years), the T1D patients in the long duration group had lower DLCO/BSA and DM/BSA compared to the controls (p < 0.05). There were no differences in any of the variables in the short duration group.

CONCLUSIONS

This study has shown that duration of diabetes is associated with decrements in diffusing capacity and its components.

Damage to skin extracellular matrix induced by UV exposure

SIGNIFICANCE

Chronic exposure to environmental ultraviolet radiation (UVR) plays a key role in both photocarcinogenesis and induction of accelerated skin aging. Although the spatiotemporal consequences of UVR exposure for the composition and architecture of the dermal extracellular matrix (ECM) are well characterized, the pathogenesis of photoaging remains poorly defined. Given the compelling evidence for the role of reactive oxygen species (ROS) as mediators of photoaging, UVR-exposed human skin may be an accessible model system in which to characterize the role of oxidative damage in both internal and external tissues.

RECENT ADVANCES

Although the cell-mediated degradation of dermal components via UVR-induced expression of ECM proteases has long been identified as an integral part of the photoaging pathway, the relative importance and identity of cellular and extracellular photosensitizers (direct hit and bystanders models, respectively) in initiating this enzymatic activity is unclear. Recently, both age-related protein glycation and relative amino-acid composition have been identified as potential risk factors for photo-ionization and/or photo-sensitization. Here, we propose a selective multi-hit model of photoaging.

CRITICAL ISSUES

Bioinformatic analyses can be employed to identify candidate UVR targets/photosensitizers, but the action of UVR on protein structure and/or ROS production should be verified experimentally. Crucially, in the case of biochemically active ECM components such as fibronectin and fibrillin, the downstream effects of photo-degradation on tissue homeostasis remain to be confirmed.

FUTURE DIRECTIONS

Both topical antioxidants and inhibitors of detrimental cell signaling may be effective in abrogating the effects of specific UVR-mediated protein degradation in the dermis.

Phrenic neuropathy in diabetic and prediabetic patients without neuromuscular complaint

Neuropathy, one of the major reasons of morbidity in diabetes mellitus (DM), is associated with prediabetic conditions as well as DM. The present study aims to compare phrenic and peripheral nerves in prediabetic, diabetic patients and healthy controls. A total of 37 diabetic, 40 prediabetic patients and 18 healthy controls were enrolled in the study. All subjects underwent conventional sensory and motor nerve conduction studies. Bilateral phrenic and peripheric nerve conduction studies were performed. In both right and left phrenic nerves, the amplitudes were lower in prediabetic and diabetic patients than control subjects, respectively (p: 0.005 and p: 0.001). Both of the phrenic nerve conductions were altered similarly. The results of our study demonstrate that phrenic nerves are affected like peripheric nerves in prediabetic and diabetic patients. We suggest reminding phrenic neuropathy in newly onset respiratory failure in diabetic and prediabetic patients.

Organ-based response to exercise in type 1 diabetes

While significant research has clearly identified sedentary behavior as a risk factor for type 2 diabetes and its subsequent complications, the concept that inactivity could be linked to the complications associated with type 1 diabetes (T1D) remains underappreciated. This paper summarizes the known effects of exercise on T1D at the tissue level and focuses on the pancreas, bone, the cardiovascular system, the kidneys, skeletal muscle, and nerves. When possible, the molecular mechanisms underlying the benefits of exercise for T1D are elucidated. The general benefits of increased activity on health and the barriers to increased exercise specific to people with T1D are discussed.

Chronic obstructive pulmonary disease and glucose metabolism: a bitter sweet symphony

Chronic obstructive pulmonary disease, metabolic syndrome and diabetes mellitus are common and underdiagnosed medical conditions. It was predicted that chronic obstructive pulmonary disease will be the third leading cause of death worldwide by 2020. The healthcare burden of this disease is even greater if we consider the significant impact of chronic obstructive pulmonary disease on the cardiovascular morbidity and mortality. Chronic obstructive pulmonary disease may be considered as a novel risk factor for new onset type 2 diabetes mellitus via multiple pathophysiological alterations such as: inflammation and oxidative stress, insulin resistance, weight gain and alterations in metabolism of adipokines. On the other hand, diabetes may act as an independent factor, negatively affecting pulmonary structure and function. Diabetes is associated with an increased risk of pulmonary infections, disease exacerbations and worsened COPD outcomes. On the top of that, coexistent OSA may increase the risk for type 2 DM in some individuals. The current scientific data necessitate a greater outlook on chronic obstructive pulmonary disease and chronic obstructive pulmonary disease may be viewed as a risk factor for the new onset type 2 diabetes mellitus. Conversely, both types of diabetes mellitus should be viewed as strong contributing factors for the development of obstructive lung disease. Such approach can potentially improve the outcomes and medical control for both conditions, and, thus, decrease the healthcare burden of these major medical problems.

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.

Alveolar gas exchange and tissue deoxygenation during exercise in type 1 diabetes patients and healthy controls

We used near-infrared spectroscopy to investigate whether leg and arm skeletal muscle and cerebral deoxygenation differ during incremental cycling exercise in men with type 1 diabetes (T1D, n=10, mean±SD age 33±7 years) and healthy control men (matched by age, anthrometry, and self-reported physical activity, CON, n=10, 32±7 years) to seek an explanation for lower aerobic capacity (˙VO2peak) often reported in T1D. T1D had lower ˙VO2peak (35±4mlkg(-1)min(-1) vs. 43±8mlkg(-1)min(-1), P<0.01) and peak work rate (219±33W vs. 290±44W, P<0.001) than CON. Leg muscle deoxygenation (↑ [deoxyhemoglobin]; ↓ tissue saturation index) was greater in T1D than CON at a given absolute submaximal work rate, but not at peak exercise, while arm muscle and cerebral deoxygenation were similar. Thus, in T1D compared with CON, faster leg muscle deoxygenation suggests limited circulatory ability to increase O(2) delivery as a plausible explanation for lower ˙VO2peak and earlier fatigue in T1D.

Glycemic control influences lung membrane diffusion and oxygen saturation in exercise-trained subjects with type 1 diabetes: alveolar-capillary membrane conductance in type 1 diabetes

Lung diffusing capacity (DLCO) is influenced by alveolar-capillary membrane conductance (D (M)) and pulmonary capillary blood volume (V (C)), both of which can be impaired in sedentary type 1 diabetes mellitus (T1DM) subjects due to hyperglycemia. We sought to determine if T1DM, and glycemic control, affected DLNO, DLCO, D (M), V (C) and SaO(2) during maximal exercise in aerobically fit T1DM subjects. We recruited 12 T1DM subjects and 18 non-diabetic subjects measuring DLNO, DLCO, D (M), and V (C) along with SaO(2) and cardiac output (Q) at peak exercise. The T1DM subjects had significantly lower DLCO/Q and D (M)/Q with no difference in Q, DLNO, DLCO, D (M), or V (C) (DLCO/Q = 2.1 ± 0.4 vs. 1.7 ± 0.3, D (M)/Q = 2.8 ± 0.6 vs. 2.4 ± 0.5, non-diabetic and T1DM, p < 0.05). In addition, when considering all subjects there was a relationship between DLCO/Q and SaO(2) at peak exercise (r = 0.46, p = 0.01). Within the T1DM group, the optimal glycemic control group (HbA1c <7%, n = 6) had higher DLNO, DLCO, and D (M)/Q than the poor glycemic control subjects (HbA1c ≥ 7%, n = 6) at peak exercise (DLCO = 38.3 ± 8.0 vs. 28.5 ± 6.9 ml/min/mmHg, DLNO = 120.3 ± 24.3 vs. 89.1 ± 21.0 ml/min/mmHg, D (M)/Q = 3.8 ± 0.8 vs. 2.7 ± 0.2, optimal vs. poor control, p < 0.05). There was a negative correlation between HbA1c with DLCO, D (M) and D (M)/Q at peak exercise (DLCO: r = -0.70, p = 0.01; D (M): r = -0.70, p = 0.01; D (M)/Q: r = -0.68, p = 0.02). These results demonstrate that there is a reduction in lung diffusing capacity in aerobically fit athletes with T1DM at peak exercise, but suggests that maintaining near-normoglycemia potentially averts lung diffusion impairments.

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.

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.

Clinical significance of pulmonary function tests in patients with acute pancreatitis

The aim of the present study was to investigate changes in pulmonary function tests (PFTs) in patients with acute pancreatitis (AP), to compare them with those changes in healthy controls, and to analyze the relationship between these parameters and computed tomography severity index (CTSI) and Ranson's criteria scores as markers of disease severity. This study included 40 patients with AP without a diagnosis of any pulmonary disease and 40 sex- and age-matched healthy controls. All participants were evaluated with simple PFTs and single-breath carbon monoxide (CO) diffusion tests. Patients with AP were also evaluated according to their CTSI and Ranson's criteria scores as markers of disease severity. The forced vital capacity (FVC), forced expiratory volume in the first second (FEV(1)), FEV(1)/FVC, and peak expiratory flow, which determine lung capacity, were similar in the two groups. The forced expiratory volume during the middle half of the FVC (FEF(25 - 75%)), CO diffusing capacity (D(LCO)), and ratio of D(LCO) to alveolar ventilation (D(LCO)/V(A)), which determines alveolar membrane permeability, revealed a statistically significant decline in pulmonary gas exchange in patients with AP (P < 0.05). Correlation analysis showed that there is a significant negative relationship between CTSI and Ranson's criteria scores with FEF(25 - 75%), D(LCO), and D(LCO)/V(A) (P < 0.05). We suggest that AP may cause impaired alveolar gas exchange without manifest pulmonary diseases. The effect of AP on FEF(25 - 75%), D(LCO), and D(LCO)/V(A) appears to be dependent not only on the disease, but also on its severity. FEF(25 - 75%), D(LCO), and D(LCO)/V(A) may give additional prognostic information in patients with AP in the initial evaluation.

Influence of fat pad removal on patellar tendon length during growth

During various knee operations, the changes caused by the surgical invasion to the infrapatellar fat pad (IPF) is still unknown. If any changes exist, it will have great influence especially on growing generations. Eighty-four Japanese white rabbits (6-month-old) were divided into three groups: the resection group involving resection of the IPF, the graft group involving resection and reimplantation of the IPF, and the no-surgery group. All these surgical procedures were done in right knees. In all left knees, only arthrotomy was performed, serving as the sham side. After 3, 6, 12, and 24 weeks of the operation, the rabbits were killed. Lengths of the patellar tendon and patellar were measured in lateral X-ray. In order to eliminate individual differences in the patellar height, we defined a new index as percent patellar height (PPH) which indicated the percentage of the patellar height of surgery side compared with that of the sham side. The PPH was 90.6% (3 weeks), 83.0% (6 weeks), 73.6% (12 weeks), and 74.7% (24 weeks) in the resection group, while it was 88.4% (6 weeks), and 88.9% (24 weeks) in the graft group. Postsurgical scar tissue formation occurring where the IPF was removed prevented the normal growth of the patellar tendon. Reimplantation of the IPF lessened the adhesion of the patellar tendon to the surrounding tissue, and better growth of the tendon. These results showed that preservation of the IPF in young individuals could be crucial for the normal growth of the patellar tendon, and critical as well for the prevention of the degeneration of the articular surface.

Aerobic exercise capacity in normal adolescents and those with type 1 diabetes mellitus

OBJECTIVE

To compare the aerobic exercise capacity between normal adolescents and those with type 1 diabetes mellitus (T1DM).

METHODS

An experimental group with 72 individuals diagnosed with T1DM aged 9--20, time from diagnosis 4.9 +/- 3.6 yr, without clinical cardiopulmonary disease or anemia and a control group (C) with 46 healthy individuals aged 10--18, matched by age, weight, height, body mass index, and lean and fat mass (kg), underwent an incremental aerobic exercising test on a motorized treadmill, where gas exchange variables - peak pulmonary ventilation (VE), peak oxygen consumption (VO(2)), and carbon dioxide production (CO(2)) - as well as their heart rate (HR) and time to exhaustion were recorded.

RESULTS

Body mass composition had no significant difference between experimental and control groups, and male and female subjects had similar exercising performances. The mean of hemoglobin A1c in the control group was 5.2+/- 0.9% and in the diabetic group 8.1+/- 2.2%; p=0.000. The patients with T1DM showed lower levels of aerobic capacity than the control group. Their respective values for each variable were as follows: (i) maximal VO(2) (T1DM: 41.57+/-7.68 vs. C: 51.12+/- 9.94 mL/kg/min; p< 0.001) and (ii) maximal VE (T1DM: 76.39+/-19.93 vs. C: 96.90 +/- 25.72 mL/kg/min; p< 0.001). Patients with T1DM also had an earlier time to exhaustion (T1DM: 8.75+/-1.60 vs. 10.82+/-1.44 min).

CONCLUSIONS

Adolescent patients with T1DM showed a reduced aerobic exercising capacity when compared to healthy peers matched to anthropometric conditions. This potential condition should be taken into consideration by the time of evaluation of the aerobic performance of these patients with glycemic control level.

Reduced pulmonary endothelium-bound angiotensin converting enzyme activity in diabetic rabbits

We examined the effects of diabetes on pulmonary capillary endothelial cell (EC) function in diabetic rabbits. One, three and six weeks after alloxan treatment, rabbits were anesthetized and pulmonary endothelium-bound angiotensin converting enzyme (ACE) activity was estimated from the single-pass transpulmonary hydrolysis of benzoyl-Phe-Ala-Pro (BPAP), an ACE specific substrate. ACE activity significantly decreased in 1- and 3-week diabetic rabbits and returned to control levels at 6 weeks. Capillary dilation, parenchymal hemorrhage and erythrocyte clumping were maximal in 3-week diabetic rabbits. We conclude that in the alloxan-diabetic rabbit, there are transient functional and more persistent morphological alterations.

Lung function and glucose metabolism: an analysis of data from the Third National Health and Nutrition Examination Survey

Although people with diabetes have decreased lung function, the dose-response relation between measures of glucose control and lung function in nondiabetic people is not known. The authors used data from the Third National Health and Nutrition Examination Survey (1988-1994) to investigate the relation between glucose tolerance test response and other measures of glucose homeostasis and lung function in an adult population without a clinical diagnosis of diabetes. Plasma glucose level 2 hours after oral administration of 75 g of glucose was inversely related to forced expiratory volume in 1 second (FEV(1)), with a difference of -144.7 ml (95% confidence interval: -231.9, -57.4) for persons in the highest quintile of postchallenge glucose compared with the lowest. Similar inverse associations with FEV(1) were found for other measures of glucose autoregulation. Lung function did not appear to be related to fasting glucose level. Similar associations were seen for forced vital capacity (FVC) but not for the FEV(1):FVC ratio. In the total study population, persons with previously diagnosed diabetes had an FEV(1) 119.1 ml (95% confidence interval: -161.5, -76.6) lower than persons without diabetes. This effect was greater in those with poorly controlled diabetes. These findings suggest that impaired glucose autoregulation is associated with impaired lung function.

Metabolic and Cardiovascular Parameters in Type 1 Diabetes at Extreme Altitude

PURPOSE

The American Diabetes Association states that physical activity can be performed by individuals with Type 1 diabetes. Nevertheless, extreme altitude mountaineering represents a demanding challenge. We present the metabolic and cardiovascular parameters found in individuals with Type 1 diabetes during the ascent to Cho Oyu located at a height of 8201 m.

METHODS

Six individuals with Type 1 diabetes and 10 matched controls participated in the expedition. Both groups were evaluated before and after 4 h of trekking for vital indices, blood gases, acute mountain sickness, and metabolic control at 0, 3700, and 5800 m.

RESULTS

No difference between the groups was observed in acute mountain sickness scores. There was a progressive elevation in basal heart rates in both groups at increasing altitude while no changes were observed in mean blood pressures. After the 3 h of trekking, a significant increase in heart rate was observed in the controls at 0 m whereas a significant decrease in blood pressure was observed at higher altitude only in controls. HbA1c levels were worse after the expedition in both groups. A progressive increase in insulin requirement was observed in subjects with Type 1 diabetes (38 +/- 6 U x d(-1) at 0 m to 51 +/- 6 at 4200 m, P < 0.001). At an altitude of 5800 m, there was a significant increase in blood lactate concentration, independently of the activity level in the two groups.

CONCLUSIONS

At extreme altitude, highly motivated trekkers with Type 1 diabetes but free from long-term complications present metabolic and cardiovascular parameters comparable with those of control subjects despite a worsening in metabolic control. This type of physical activity must be accompanied by careful glucose monitoring.

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.

Alveolar gas exchange in patients with type 2 diabetes mellitus

The present study has been conducted to quantify and compare the capacity of gas exchange in patients with type 2 diabetes mellitus (DM) and healthy controls and also to investigate the effects of various factors on alveolar capillary permeability. A total of 37 subjects, 25 patients with DM and 12 healthy controls were recruited for the study. All the participants were evaluated with simple spirometric tests and simple breath carbonmonoxide (CO) diffusion test (DLCO). The ratio of DLCO value to the alveolar ventilation (VA) was used to assess alveolar membrane permeability. Diabetic patients were also evaluated in detail with respect to degenerative diabetic complications including the presence of microalbuminuria, advanced nephropathy, sensorial and autonomic neuropathy, retinopathy, hypertension and macrovascular disease. The results of simple spirometric tests which determined lung capacity were similar in the diabetic patients and the healthy controls. Ratio of DLCO/VA, which determines alveolar membrane permeability, revealed statistically significant decline in pulmonary gas exchange in the diabetic group (p: 0.037). Pearson correlation analysis revealed statistically significant correlation between duration of diabetes mellitus, age and urinary albumin excretion with DLCO/VA values (Pearson: -0.726, p: 0.001; Pearson: -0.438, p: 0.036; Pearson: -0.472, p: 0.023 respectively). This study demonstrated the decreased alveolar gas exchange capacity in diabetic patients compared with healthy controls. Detrimental effects of DM on alveolar capillaries were found to be correlated with age, duration of DM and urinary albumin excretion. Microalbuminuria was the only significant predictor of DLCO/VA.

Association between glycemic state and lung function: the Framingham Heart Study

Diabetes mellitus has been inconsistently associated with a reduced level of pulmonary function. To elucidate this association further, we analyzed the relationship of diabetes and of fasting blood glucose to the level of pulmonary function assessed by spirometry in the 3,254 members of the Framingham Offspring Cohort. Diabetes was defined as a fasting blood glucose of 126 mg/dl or more or pharmacologic treatment. Subjects were classified as current, former, or never smokers based on questionnaire responses. Predicted pulmonary function was determined from the coefficients of a regression of pulmonary function on age, sex, and body habitus in the 1,110 never smokers. Both the diagnosis of diabetes and a higher level of fasting blood glucose were associated with lower than predicted levels of pulmonary function. The adverse effect of diabetes and glycemic level on pulmonary function was stronger among ever smokers than never smokers, suggesting an interaction between the level of fasting glycemia and tobacco smoking.

Diabetes mellitus vs. Raynaud disease: different lung vascular bed disorders

BACKGROUND

In type II diabetes mellitus there are few data concerning pulmonary function abnormalities. In normal subjects and in patients with primary Raynaud phenomenon, cold pressor test induces a decrease in carbon monoxide single-breath diffusing capacity (DL,co) but not in secondary Raynaud phenomenon. Our objective was to assess evaluation of lung diffusion capacity postural changes in diabetes mellitus and in secondary Raynaud phenomenon, two diseases with different pulmonary capillaries functional disorders.

METHODS

Twenty-five patients with type II diabetes mellitus (mean age 52.24 years), 17 patients with secondary Raynaud phenomenon (mean age 47.06 years), non-smokers without pulmonary or heart disease, and 26 healthy matched subjects (mean age 47.50 years) underwent lung diffusion capacity measurements by single-breath method also corrected by alveolar volume (DL,co) in sitting and supine positions.

RESULTS

Patients with diabetes mellitus exhibited lower values of DL,co and DL,co/VA measurements in comparison with subjects with Raynaud phenomenon and control group (p <0.01). Additionally, they had a significant decrease in DL,co in supine compared to sitting position (83.88 +/- 16.53 vs. 89.68 +/- 18.03, p = 0.023). To the contrary, supine position in secondary Raynaud phenomenon and in control group after cold pressor test showed a significant increase in DL,co/VA (120.93 vs. 109.78 in Raynaud and 114.36 vs. 99.47 in control group, p <0.001).

CONCLUSIONS

Postural changes of lung diffusion capacity could be used as a simple, non-invasive method to detect vascular disease resulting from different pathophysiologic mechanisms such as diabetes mellitus and Raynaud phenomenon.

Combination of vitamin C and rutin on neuropathy and lung damage of diabetes mellitus rats

We investigated the role of vitamin C or rutin on neuropathy and lung damage of diabetic mellitus (DM) rats. Norepinephrine content was significantly decreased in sciatic nerves'of DM rats compared with non-DM controls but vitamin C had no effect on decreases of norepinephrine. 2,4-dinitrophenylhydrazine (DNPH) incorporation, which is biomarker of protein oxidation, was increased in sciatic nerve of DM rats as compared with normal control. However, vitamin C had no effects on increases of DNPH incorporation. We measured the content of conjugated dienes (CD) as a biomarker of lipid oxidation in sciatic nerve. CD was increased in DM as compared with normal control. Vitamin C or rutin had no effects on increases of CD. However, Rutin plus vitamin C significantly decreased the content of CD as compared with DM rats. In lung of DM rats, DNPH incorporation or CD was increased as compared with normal control. Vitamin C or Rutin had no effects on increases of CD. However, Rutin plus vitamin C significantly decreased the content of DNPH incorporation or CD in lung tissue. Vitamin C caused marked pathological changes such as the increases of parenchyma and the thickening of alveolar septa in the lung of DM. Rutin had protective effects on the pathological changes in the lung of DM rats. In conclusion, Vitamin C had no effects on oxidative parameter, such as DNPH incorporation or CD, and on the decreases of norepinephrine content in DM rats. Vitamin C caused the marked pathological changes in the lung of DM rats but rutin had protective effects against the pathological changes.

Extreme altitude mountaineering and Type 1 diabetes; the Diabetes Federation of Ireland Kilimanjaro Expedition

AIMS

To examine the effects of extreme altitude mountaineering on glycaemic control in Type 1 diabetes, and to establish whether diabetes predisposes to acute mountain sickness (AMS).

METHODS

Fifteen people with Type 1 diabetes and 22 nondiabetic controls were studied during the Diabetes Federation of Ireland Expedition to Kilimanjaro. Daily insulin requirements, blood glucose estimations and hypoglycaemic attacks were recorded in diaries by the people with diabetes. The performance of blood glucose meters at altitude was assessed using standard glucose solutions. Symptoms of acute mountain sickness were recorded daily by people with diabetes and by the nondiabetic controls using the Lake Louise Scoring Charts. The expedition medical team recorded the incidence of complications of altitude and of diabetes. The final height attained for each individual was recorded by the expedition medical team and verified by the expedition guides.

RESULTS

The final altitude ascended was lower in the diabetic than the nondiabetic group (5187 +/- 514 vs. 5654 +/- 307 m, P = 0.001). The mean daily insulin dose was reduced from 67.1 +/- 28.3-32.9 +/- 11.8 units (P < 0.001), but only 50% of recorded blood glucose readings were within the target range of 6-14 mmol/L. There were few hypoglycaemic attacks after the first two days of climbing. Both blood glucose meters tested showed readings as low as 60% of standard glucose concentrations at high altitude and low temperatures. The Lake Louise questionnaires showed that symptoms of AMS occurred equally in the diabetic and nondiabetic groups. There were two episodes of mild diabetic ketoacidosis; two of the diabetic group and three of the nondiabetic group developed retinal haemorrhages.

CONCLUSIONS

People with Type 1 diabetes can participate in extreme altitude mountaineering. However, there are significant risks associated with this activity, including hypoglycaemia, ketoacidosis and retinal haemorrhage, with the additional difficulties in assessing glycaemic control due to meter inaccuracy at high altitude. People with Type 1 diabetes must be carefully counselled before attempting extreme altitude mountaineering.

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.

Reduction of diffusion capacity for carbon monoxide in diabetic patients

Diabetes can cause the development of pulmonary complications due to collagen and elastin changes, as well as microangiopathy. This study demonstrates the relationship between pulmonary complications and other chronic complications in diabetes. Twenty-seven patients with diabetes, aged 21 to 62 years, who had had the disease from 3 to 32 years, were included in this study. The protein excretion rate (PER) and the diffusion capacity of the lung for carbon monoxide (DLCO) were included as parameters of the severity of complications. PER was determined by the Biuret method. DLCO was measured by the single-breath method and was corrected by the measurement of alveolar volume (VA). The values of DLCO as corrected by VA (DLCO/VA) were included in the statistical evaluation of the results. The variables of age, duration of diabetes, and complication parameters were included in a multiple regression model with forward, stepwise selection to assess their value in predicting DLCO/VA. The variables were found to be significant predictors of DLCO/VA (R2 = 0.46, adjusted R2 = 0.32, p < 0.022). However, proteinuria was the only significant independent predictor of DLCO/VA. This finding indicates that both renal and pulmonary complications of diabetes share a similar microangiopathic background.

Postural variations of pulmonary diffusing capacity in insulin-dependent diabetes mellitus

STUDY OBJECTIVE

To assess whether posture-related changes of diffusing capacity could be considered as an early sensitive marker of pulmonary abnormalities in patients with insulin-dependent diabetes mellitus (IDDM) and whether the postural variations of pulmonary capillary blood volume (Vc) could reflect the lung capillary damage that characterizes the diabetic microangiopathy.

DESIGN

Carbon monoxide diffusing capacity (DCO) was measured by the single-breath method. Four DCO measurements, two in sitting and two in supine position, were performed in each subject using gas mixtures containing different oxygen concentrations. Membrane and capillary volume components of the diffusion capacity were calculated and both were expressed as absolute value and corrected by alveolar volume (VA).

PATIENTS

Twenty IDDM patients and 20 normal subjects matched for age and sex were studied.

MEASUREMENTS AND RESULTS

The IDDM patients showed normal pulmonary volumes and flows. No significant differences between the two groups were found for DCO, coefficient of diffusion, Vc, and pulmonary capillary blood volume corrected by alveolar volume in sitting position. All these indexes significantly increased in normal subjects but not in diabetics, by changing the posture of the subject from sitting to supine position. In a multivariate analysis, the presence of diabetes mellitus and the age of the subjects were the only significant predictors of Vc postural changes.

CONCLUSIONS

This postural test, adjusted for age, could be included in a screening diagnostic procedure for an early assessment of pulmonary abnormalities in diabetic patients. The lack of Vc postural increase in diabetics could reflect the presence of a microangiopathy involving the pulmonary small vessels.

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)

Indications of reduced pulmonary function in type 1 (insulin-dependent) diabetes mellitus

Abnormalities of pulmonary function tests have been described in type 1 (insulin-dependent) diabetes mellitus (IDDM). To better characterise such abnormalities and to verify whether these latter are associated with the presence of diabetic microvascular disease we compared 23 non-smoking patients who had IDDM with 24 non-smoking healthy control subjects strictly matched for sex, age, and body mass index. Compared with controls, diabetic patients had a reduced forced vital capacity (FVC) (87.5 +/- 13.1% vs. 96.4 +/- 13.6% of the predicted; P = 0.03) and forced expiratory volume in 1 s (FEV1) (90.5 +/- 17.7% vs. 101.2 +/- 13.2% of the predicted; P = 0.02). While within the group of patients the presence of retinopathy and autonomic neuropathy were not associated with modifications of pulmonary function tests, those with altered urinary albumin excretion rate (AER > or = 20 micrograms/min; range 21-589) (n = 7) had a significantly lower pulmonary diffusion capacity (DLCO) than the 16 normoalbuminuric subjects (62.6 +/- 7.2% vs. 88.7 +/- 20.1% of the predicted; P = 0.01). Moreover, in the group of patients, DLCO was inversely related with AER (r = -0.43; P = 0.04). In conclusion, IDDM is characterised by reduced FVC and FEV1, while a significant decrease in DLCO may be considered as selectively associated with renal disease.

Diabetes mellitus in cystic fibrosis: effect of insulin therapy on lung function and infections

The effect of insulin therapy on lung function and lung infections was studied in a retrospective case-control design in 18 diabetic cystic fibrosis (CF) patients; 18 non-diabetic CF patients, matched for sex, age and presence of chronic Pseudomonas aeruginosa lung infection, served as controls. Parameters of CF clinical status were collected for six years before and two years after the onset of insulin therapy in the diabetic patients. Before onset of insulin therapy, body mass index (BMI) and forced vital capacity (FVC) in (pre)diabetic patients deviated increasingly from those in control patients. Decreases in BMI and lung function during the past three months before onset of insulin therapy were reverted within three months of insulin therapy. From three months to two years after onset of insulin therapy, differences in BMI and lung function diminished between diabetic and control patients. After two years of insulin therapy, BMI was similar in diabetic and non-diabetic patients and the percentage differences in forced expiratory volume in 1s (FEV1) and FVC between the two groups were similar to those found six years before the onset of insulin therapy. The finding that insulin therapy improves lung function in diabetic CF patients suggests strongly that the insidious decline in lung function seen during the years before the diagnosis of diabetes mellitus results from the pre-diabetic condition. After onset of insulin therapy, the percentages of sputum examinations positive for Haemophilus influenzae and Streptococcus pneumoniae decreased in the diabetic patients, whereas parameters of lung infections with P. aeruginosa and Staphylococcus aureus remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)