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

Fungal and bacterial co-infections of the respiratory tract among patients with COVID-19 hospitalized in intensive care units

Backgrounds

The pandemic of COVID-19 has created a global public health crisis. ICU patients with COVID-19 are prone to infections of bacterial and/or fungal origins due to several risk factors. Consequently, the current study was conducted to evaluate the frequency, demographic characteristics, underlying conditions, and etiologic agents of fungal and bacterial co-infections of the respiratory tract among ICU patients with COVID-19 in Iran.

Materials and methods

From May to October 2020, sputa and endotracheal aspirates were collected from ICU patients hospitalized with COVID-19 who also were suspected of bacterial and/or fungal co-infections according to inclusion criteria. The etiologic agents of bacterial co-infections were identified using the Vitek 2 identification method. For fungal identification, all samples were analyzed by direct microscopy using KOH 10% and culture. Furthermore, all isolates were subjected to sequencing method.

Results

A total of 73 lung specimens were obtained from patients who met the inclusion criteria. Of these, in 15 cases (20.54%) fungal and/or bacterial co-infections were confirmed. Males were more infected (73.33%) and all of them were between 49 and 79 years. Candida albicans (n = 8, 61.53%) and Klebsiella pneumoniae (n = 5, 38.46%) were the most frequent etiologic agents related to fungal and bacterial co-infections, respectively. Pneumonia (n = 15, 100%) and diabetes mellitus (n = 8, 53.33%) were documented as the most prevalent underlying conditions. In the current study, 3 out of 15 patients (20%) died.

Conclusion

The frequency of bacterial co-infections of the respiratory tract in ICU patients hospitalized with COVID-19 was relatively high. According to the results, one of the causes of death of these patients could be a secondary infection.

Diabesity Associates with Poor COVID-19 Outcomes among Hospitalized Patients

Background

Although numerous studies have investigated obesity's negative effect on coronavirus disease 2019 (COVID-19) outcomes, only a limited number focused on this association in diabetic patients. In this study, we analyzed the association between obesity and COVID-19 outcome (death, intensive care unit [ICU] admission, mechanical ventilation needs, quick Sequential Organ Failure Assessment [qSOFA] score, and confusion, urea, respiratory rate, blood pressure [CURB-65] scores) for hospitalized diabetic patients.

Methods

In this prospective hospital-based registry of patients with COVID-19 in East Azerbaijan, Iran, 368 consecutive diabetic patients with COVID-19 were followed from admission until discharge or death. Self-reported weight and height were used to calculate body mass index (kg/m²) upon admission. Our primary endpoint was analyzing obesity and COVID-19 mortality association. Assessing the associations among obesity and disease severity, ICU admission, and mechanical ventilation was our secondary endpoint.

Results

We analyzed data from 317 patients and found no significant difference between obese and non-obese patients regarding frequency of death, invasive mechanical ventilation, ICU admission, CURB-65, or qSOFA scores (P>0.05). After adjusting for confounding factors, obese diabetic COVID-19 patients were 2.72 times more likely to die than non-obese patients. Moreover, ventilator dependence (adjusted odds ratio [aOR], 1.87; 95% confidence interval [CI], 1.03-4.76) and ICU admission (aOR, 2.41; 95% CI, 1.11-5.68) odds were significantly higher for obese patients than non-obese patients.

Conclusion

The results of the present study indicated that obesity worsens health outcomes for diabetic COVID-19 patients.

The association between the level of serum 25(OH) vitamin D, obesity, and underlying diseases with the risk of developing COVID-19 infection: A case-control study of hospitalized patients in Tehran, Iran

BACKGROUND AND OBJECTIVES: The outbreak of COVID-19 has created a global public health crisis. Little is known about the predisposing factors of this infection. The aim of this study was to explore an association between the serum vitamin D level, obesity, and underlying health conditions, as well as the vulnerability to COVID-19 in the Iranian population.

METHODS

We conducted a case-control study of 201 patients with coronavirus infection and 201 controls. Cases and controls were matched for age and gender. The study was carried out for 2 months (February 2020-April 2020) at Imam Khomeini Hospital Complex, Tehran, Iran. Serum 25(OH) vitamin D was measured using the enzyme-linked immunosorbent assay method. Information containing age, gender, clinical symptoms, body mass index, computed tomography scan findings, and underlying health conditions related to each participant were elicited from health records.

RESULTS

A significant negative correlation (p = .02) was observed between the serum vitamin D level and developing coronavirus infection. Also, the results showed that the COVID-19 cases were more likely to be overweight than the controls (p = .023). Diabetes mellitus, hypertension, and respiratory infections were found in 20.89%, 9.65%, and 6.96% of cases, respectively. These underlying health conditions were not significantly different between cases and controls (p = .81).

CONCLUSIONS

Vitamin D deficiency and obesity are two main predisposing factors associated with the vulnerability to coronavirus infection in the Iranian population.

Epidemiology, laboratory diagnosis and clinical aspects of fungal pulmonary infections in 384 patients hospitalized in pulmonary units in Guilan province, Iran

Background and Objectives:

The respiratory tract is the most common site for developing fungal infections. People who have a weakened immune system are more susceptible to respiratory system involvement with fungi. Fungal infections of the respiratory tract are largely unrecognized and their true burden is elusive. Therefore, the aim of the current study was to evaluate the clinical spectrum, demographic characteristics, risk factors, and etiology of fungal respiratory infections in 384 patients hospitalized in pulmonary units of Razi hospital, Guilan province, Iran.

Materials and Methods:

A total of 384 lung specimens (192 Bronchoalveolar lavages (BAL) and 192 sputa) were obtained from patients who met the inclusion criteria. All samples were analyzed by direct microscopy and culture. Fungal identification was accomplished by internal transcribed spacer (ITS) and beta-tubulin sequencing. Also, in patients suspected to invasive pulmonary aspergillosis BAL specimens were tested for galactomannan (GM) antigen. According to the host factors (clinical symptoms, radiology findings and predisposing factors which were defined as inclusion criteria), and the positive results in direct examination, culture and serology (GM for aspergillosis) the infection was confirmed.

Results:

Fungal respiratory infection was confirmed in 137 cases (35.67%) including 86 (62.77%) males and 51 (37.23%) females and the highest prevalence of infection was found in the age group of 46–72 years (n=75, 54.74%). Cough (n=129, 94.16%), dyspnea (n=111, 81.02%), purulent sputum (n=85, 62.04%) and weight loss (n=77, 56.2%) were the predominant symptoms. Tuberculosis (n=34, 24.81%), taking chemotherapy regimen (n=30, 21.89%) and diabetes mellitus (n=27, 19.70%) were the predominant underlying conditions. Candida albicans (37.22%) and Candida tropicalis (21.89%) represent the two most commonly isolated species in the current study. Furthermore, according to revised EORTC/MSG (2008) definitions for invasive fungal infections, from 5 cases of pulmonary aspergillosis, 2 (40%) cases of probable invasive pulmonary aspergillosis (IPA) and 3 (60%) cases of possible IPA were diagnosed.

Conclusion:

According to the results of this study, infected infants with congenital CMV infection could identify at early stage by testing Guthrie cards (within 21 days of life). Furthermore, since there is a lack of CMV knowledge in our population, educating and effective counseling by obstetricians/gynecologists to the pregnant women are recommended.

Relationship between pulmonary function and albuminuria in type 2 diabetic patients with preserved renal function

BACKGROUND

Albuminuria is the early manifestation of the pathogenesis of diabetic nephropathy (DN). The current study was to investigate the relationship of pulmonary function with albuminuria in type 2 diabetic patients with preserved renal function to evaluate the role of pulmonary function in the early stage of DN.

METHODS

A total of 326 patients with type 2 diabetes mellitus (T2DM) including 270 without albuminuria and 56 with albuminuria, and 265 non-diabetic patients were enrolled. The patients' general information, and the parameters of pulmonary function, including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC, total lung capacity (TLC), diffusion capacity for carbon monoxide of lung (DLCO) were compared between T2DM and control groups, as well as T2DM patients with and without albuminuria groups. All pulmonary function parameters were expressed as a percentage of those predicted (%pred). Logistic regression models were constructed to test the association of albuminuria and pulmonary function.

RESULTS

The values of FVC%pred, FEV1%pred, TLC%pred and DLCO%pred were lower, and the proportion of subjects with FVC%pred < 80, FEV1%pred < 80, and DLCOc%pred < 80 was higher in T2DM subjects than controls (all P < 0.05). Subgroup analysis of diabetic patients showed that the values of FVC%pred, FEV1%pred, TLC%pred, and DLCOc%pred (97.18 ± 13.45, 93.95 ± 14.51, 90.64 ± 9.97, 87.27 ± 13.13, respectively) were significantly lower in T2DM subjects with albuminuria than those without albuminuria (103.94 ± 14.12, 99.20 ± 14.25, 93.79 ± 10.36, 92.62 ± 13.45, all P < 0.05). There was a significantly negative correlation between the urine albumin-to-creatinine ratio (UACR) and DLCOc%pred (r = - 0.143, P = 0.010) in spearman linear correlation test. In logistic regression analysis, the FVC%pred (OR 0.965, 95%CI 0.944-0.988), FEV1%pred (OR 0.975, 95%CI 0.954-0.996), and DLCOc%pred (OR 0.974, 95%CI 0.951-0.998) were independently associated with albuminuria after adjustments for smoking index, duration, HbA1c, FBG, and TG.

CONCLUSION

Our results demonstrated albuminuria is associated with a restrictive pulmonary function as well as pulmonary diffusion function in T2DM with preserved renal function, which remind us to be alert of the pulmonary function decline even in the early stage of DN.

Fungal Isolates of the Respiratory Tract in Symptomatic Patients Hospitalized in Pulmonary Units: A Mycological and Molecular Epidemiologic Study

Introduction

Fungal respiratory infections are being recognized with increasing frequency in parallel with an expanding population of immunocompromised patients. In most cases, colonization is the first step in the progression to pulmonary fungal infection. This study was designed to evaluate the distribution of fungal elements in the respiratory tract of symptomatic patients hospitalized in pulmonary units.

Methods

This descriptive cross-sectional study was carried out over a period of two years, from October 2017 to October 2019 in Guilan province, located in Iran’s northern region. In the current study, bronchoalveolar lavage or sputum specimens were collected. All samples were analyzed by direct microscopy using KOH 10% and culture. Fungal identification was accomplished by internal transcribed spacer (ITS) and beta-tubulin sequencing. Also, in patients suspected of invasive pulmonary aspergillosis, BAL specimens were tested for galactomannan (GM) antigen.

Results

A total of 384 lung specimens (192 bronchoalveolar lavage (BAL) and 192 sputum samples) were obtained from symptomatic patients hospitalized in pulmonary units. Of these, 137 (35.67%) were positive in direct examination and culture. Among the 137 positive cases, most isolates were from male patients 86 (62.77%) and most of them were between 46 and 72 years. Candida albicans (37.22%) and Candida tropicalis (21.89%) represent the two most commonly isolated species in the current study. Cough (94.16%), dyspnea (81.02%), purulent sputum (62.04%) and weight loss (56.2%) were the predominant symptoms and tuberculosis (24.81%), chemotherapy (21.89%) and diabetes mellitus (19.70%) were the predominant underlying conditions. Also, 5 cases of invasive pulmonary aspergillosis and 1 case of mucormycosis were diagnosed.

Conclusion

Candida albicans was the most common fungal species isolated from symptomatic patients hospitalized in pulmonary units. Tuberculosis, chemotherapy and diabetes mellitus were important underlying conditions for pulmonary fungal colonization and/or infection.

Pre- and postoperative respiratory muscle strength, body mass index and fasting glucose profile of patients with type 2 diabetes mellitus submitted to metabolic surgery

Abstract Introduction: The lung is considered a target organ in diabetes mellitus as a consequence of alterations secondary to chronic hyperglycemia that compromise respiratory muscle strength. Metabolic surgery for improving diabetes mellitus has beneficial effects on weight loss and glucose metabolism. Objective: The objective of this study was to evaluate the respiratory muscle strength, assessed by MIP and MEP, body mass index (BMI) and fasting glucose profile of patients with type 2 diabetes mellitus before and after metabolic surgery without gastric resection. Method: Seventeen patients with type 2 diabetes mellitus participated in the study. The participants had a mean age of 44.8 ± 11.81 years. Results: The results showed a significant decrease of MEP values in the immediate postoperative period when compared to the preoperative period (p=0.001), while no significant results were obtained for MIP. Regarding BMI and fasting glucose, significant weight loss and a significant reduction in fasting glucose levels were observed in the late postoperative period (p=0.006 and p=0.007, respectively). Conclusion: The MIP and MEP were reestablished and satisfactory results were obtained for BMI and fasting glucose in the late postoperative period. Further studies are needed to monitor patients in the pre- and postoperative period of metabolic surgery, identifying complications and acting on the care and recovery of these patients.

Exendin-4 partly ameliorates - hyperglycemia-mediated tissue damage in lungs of streptozotocin-induced diabetic mice

Glucagon-like peptide-1 (GLP-1) stimulates insulin secretion, - plays anti-inflammatory role in atherosclerosis, and has surfactant-releasing effects in lungs. GLP-1 analogues are used in diabetes therapy. This is the first study to investigate the effects of exendin-4, a GLP-1 receptor agonist, on lung injury in diabetic mice. BALB/c male mice were divided into four groups. The first group was given only citrate buffer, the second group was given only exendin-4, the third group was given only streptozotocin (STZ), and the fourth group was given both exendin-4 and STZ. Exendin-4 (3μg/kg) was administered daily by subcutaneous injection for 30days after mice were rendered diabetic with a single dose of STZ (200mg/kg). Structural alterations, oxidative stress, apoptosis, insulin signaling and expressions of prosurfactant-C, alpha-smooth muscle actin, collagen-I and fibronectin were evaluated in lung tissue. Diabetic mice lungs were characterized by induced oxidative stress, apoptosis, edema, and cell proliferation. They had honeycomb-like alveoli, thicker alveolar walls, and hypertrophic pneumocytes. Although exendin-4 treatment improved pulmonary edema, apoptosis, oxidative stress, and lung injury, it led to the disrupted insulin signaling and interstitial collagen accumulation in the lungs of diabetic mice. Exendin-4 ameliorates hyperglycemia-mediated lung damage by reducing glucose, -oxidative stress and stimulating cell proliferation. However, exendin-4 led to increased lung injury partly by reducing insulin signaling - and collagen accumulation around pulmonary vasculature in diabetic mice.

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.

Chard (Beta vulgaris var. cicla) extract improved hyperglycemia-induced oxidative stress and surfactant-associated protein alterations in rat lungs

CONTEXT

Chard is used as an antidiabetic agent by the diabetic patients in Turkey.

OBJECTIVE

The effect of chard extract [Beta vulgaris L. var. cicla (Chenopodiaceae)] on the antioxidant system and the expression of surfactant-associated proteins (SP) in the lungs of hyperglycemic rats were examined.

MATERIALS AND METHODS

Hyperglycemia was induced by a single dose of streptozotocin (60 mg/kg) provided intraperitoneally. Fourteen days after the rats were rendered hyperglycemic, the chard (2 g/kg/d), insulin (6 U/kg/d), and chard plus insulin (as mentioned above) were administered to rats for 45 d. On day 60, rats' lungs were removed. Oxidative stress parameters and SP expression were assayed.

RESULTS

The lungs of hyperglycemic rats were characterized by the induced lipid and protein oxidation, elevated myeloperoxidase and xanthine oxidase activities, decreased glutathione levels, and reduced tissue factor and antioxidant enzymes activities (catalase, superoxide dismutase, glutathione peroxidase, and glutathione-S-transferase). Chard treatment alone and chard treatment combined with insulin were capable of achieving a regression of pulmonary oxidative stress, by inhibiting lipid and protein oxidation, and restoring the antioxidant system of hyperglycemic rats. SP-A expressions were significantly unchanged in all groups, whereas pro-SP-C and SP-D expressions were reduced in hyperglycemic rats. Pro-SP-C and SP-D levels were increased by chard and insulin administrations alone and combined in hyperglycemic rats.

DISCUSSION AND CONCLUSION

All treatments have a positive effect on the surfactant and antioxidant systems of the lungs of hyperglycemic rats. The best therapeutic effect was provided by treatment with chard extract alone in the compensation of hyperglycemic symptoms.

Assessment of lung function by spirometry and diffusion study and effect of glycemic control on pulmonary function in type 2 diabetes mellitus patients of the eastern India

INTRODUCTION

There are so many complications involving eyes, kidneys, lungs and nerves associated with diabetes. But, pulmonary complications are poorly characterized among eastern Indian diabetic populations.

AIMS AND OBJECTIVES

To assess pulmonary function in patients with type 2 diabetes mellitus. To find out correlation of the pulmonary functions test variables with Glycemic control.

MATERIALS AND METHODS

Total of 60 type 2 diabetes patient of age between 35-55 y and same number of age and sex matched apparently healthy control individual were included in the present study. All subjects were evaluated for PFT by flow sensitive spirometer (RMS HELIOS-401), the spirometric parameters were measured as a percentage of predicted and DLCO (by single breath technique). HBA1c of all cases were measured and they were grouped according to HBA1c level (Group-a =>7%, Group-b =6%-7%, Group-c =<6%).

RESULTS

Significant differences in the spirometric parameters (FVC, FEV1/FVC) and diffusion capacity (DLCO% and DL/VA%) existed between cases and controls. There was a significant decrease in FVC, DLCO and DL/VA and significant increase in FEV1/FVC in that groups having HBA1c level >7% than the other groups. FEV1, FVC, DLCO, and DL/VA were negatively correlated with HbA1c where as FEV1/FVC has positive association with HbA1c.

CONCLUSION

Significant deterioration of lung function and diffusing capacity was observed in type 2 diabetes patients with poor glycemic control.

Alterations in lung gene expression in streptozotocin-induced diabetic rats

BACKGROUND

Diabetes profoundly affects gene expression in organs such as heart, skeletal muscle, kidney and liver, with areas of perturbation including carbohydrate and lipid metabolism, oxidative stress, and protein ubiquitination. Type 1 diabetes impairs lung function, but whether gene expression alterations in the lung parallel those of other tissue types is largely unexplored.

METHODS

Lung from a rat model of diabetes mellitus induced by streptozotocin was subjected to gene expression microarray analysis.

RESULTS

Glucose levels were 67 and 260 mg/dl (p < 0.001) in control and diabetic rats, respectively. There were 46 genes with at least ± 1.5-fold significantly altered expression (19 increases, 27 decreases). Gene ontology groups with significant over-representation among genes with altered expression included apoptosis, response to stress (p = 0.03), regulation of protein kinase activity (p = 0.04), ion transporter activity (p = 0.01) and collagen (p = 0.01). All genes assigned to the apoptosis and response to stress groups had increased expression whereas all genes assigned to the collagen group had decreased expression. In contrast, the protein kinase activity and ion transporter activity groups had genes with both increased and decreased expression.

CONCLUSIONS

Gene expression in the lung is affected by type 1 diabetes in several specific areas, including apoptosis. However, the lung is resistant to changes in gene expression related to lipid and carbohydrate metabolism and oxidative stress that occur in other tissue types such as heart, skeletal muscle and kidney.

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.

Can inhaled insulin be used for the treatment of diabetes mellitus?

Reluctance to start and adequately titrate subcutaneous insulin are major reasons why many patients with diabetes mellitus are insufficiently metabolically controlled. Pulmonary insulin administration has the advantage over subcutaneous insulin in that it is noninvasive, seems better accepted by the diabetic population and exerts equal efficacy in terms of glycemic control. As such, inhaled insulin has the potential to increase the diabetic (Type 2) patient's willingness to commence and adhere to insulin therapy. Inhaled insulin's short duration of action makes it suitable for prandial administration provided that basal insulin requirements are met by residual b-cell function, or by supplemental long-acting subcutaneous insulin. In clinical trials, inhaled insulin is comparable to short-acting subcutaneous insulin with regard to efficacy and hypoglycemic risk. Adverse effects associated with inhaled insulin include dry cough, which tends to diminish over time, a slight drop in pulmonary function that does not progress and is reversible in most patients if treatment is discontinued, and increased insulin antibody formation, albeit without clinical sequelae. Long-term safety remains an issue for a product intended to be used chronically for many years. Exubera((R)) was thus far the only inhaled insulin product to receive approval in the USA and Europe for use in adults with Type 1 or Type 2 diabetes, but was recently withdrawn from the market. At present it is unclear how this decision will affect programs from other companies with inhaled insulin products under development.

Reduced respiratory muscle strength and endurance in type 2 diabetes mellitus

BACKGROUND

A restrictive lung function pattern is frequently observed in patients with diabetes mellitus (DM) and has been related to respiratory muscle dysfunction in type 1 DM or in mixed population. We aimed to verify whether such a relationship applies also to type 2 DM patients.

METHODS

The respiratory muscle function was explored in 75 non-smoking patients with type 2 DM without pulmonary or cardiac diseases and compared with that of 40 healthy non-smoking control subjects matched by age and sex. Maximal inspiratory and expiratory pressures (MIP, MEP) and maximum voluntary ventilation (MVV), which reflect respiratory muscle strength and endurance, respectively, were measured, and a complete respiratory function assessment was recorded.

RESULTS

Patients were in stable metabolic conditions and had, on average, normal total lung capacity and diffusing lung capacity for carbon monoxide. However, MIP and MVV were significantly reduced in comparison with those of control subjects. Both MIP/MEP and MVV significantly correlated with lung volumes and diffusing lung capacity for carbon monoxide. The multiple regression analysis identified age (beta coefficient = -0.238, p = 0.046), glycated haemoglobin (beta coefficient = -0.245, p = 0.047) and total lung capacity (beta coefficient = 0.430, p = 0.016) as independent correlates of MIP, whereas male sex (beta coefficient = 0.423, p = 0.004) and diabetic complications (beta coefficient = -0.248, p = 0.044) were independent correlates of MVV.

CONCLUSIONS

In type 2 DM, respiratory muscle strength was reduced and significantly related to lung volumes and quality of metabolic control, whereas impaired endurance of respiratory muscles prevailed in patients with microvascular complications.

Pulmonary diffusing capacity for carbon monoxide: a marker of depressed hypercapnic drive in type 1 diabetes mellitus?

AIMS

Decreased chemosensitivity to hypercapnia, a common finding in Type 1 diabetes mellitus, seems related to autonomic neuropathy. We proposed to verify whether simple neuroautonomic cardiovascular tests or indexes of severity of diabetes and respiratory impairment can identify patients with such a dysfunction, but no clinical evidence of autonomic neuropathy.

METHODS

Forty patients with Type 1 diabetes, 20 with autonomic neuropathy according to the results of a standardized test battery, were studied and compared with 40 normal subjects matched by age and sex. Spirometry and pulmonary diffusing capacity for carbon monoxide were performed. The chemosensitivity to hypercapnia was tested by the rebreathing method.

RESULTS

There was no significant difference between patients with and without autonomic neuropathy in chemosensitivity to hypercapnia, as expressed by the ventilation response to increasing end-tidal pressure of carbon dioxide; however, it was lower in the whole group of patients with diabetes than in control subjects (1.71 ± 0.80 vs. 2.45 ± 1.11 l⁻¹ min⁻¹ mmHg, respectively, P=0.002). No significant correlation was found between ventilation response to increasing end-tidal pressure of carbon dioxide and the results of autonomic tests. In patients with diabetes mellitus, the ventilatory response to hypercapnia significantly correlated with pulmonary diffusing capacity for carbon monoxide (Spearman's rho=0.387, P=0.013) and this was the only variable significantly associated with ventilation response to increasing end-tidal pressure of carbon dioxide in a multiple regression model.

CONCLUSIONS

Chemosensitivity to hypercapnia was depressed in patients with diabetes mellitus, irrespective of autonomic neuropathy, in comparison with control subjects. The correlation with pulmonary diffusing capacity for carbon monoxide suggests that microcirculatory damage might contribute to depress the central chemosensitivity.

Aerobic exercise capacity and pulmonary function in athletes with and without type 1 diabetes

OBJECTIVE

To compare the aerobic exercise capacity and pulmonary function between athletes with and without type 1 diabetes.

RESEARCH DESIGN AND METHODS

Fifty-one adult age-matched individuals were assessed in random order to the maximum volume of O(2) consumption (Vo(2 peak max)) (ml/kg/min), anaerobic threshold (ml/kg/min), peak pulmonary ventilation (Ve), heart rate (beats per min), time to exhaustion (min), forced vital capacity (FEV) (%), forced expiratory volume in the first second (FEV1) (%), total lung capacity (TLC) (%), and lung diffusion capacity for carbon monoxide (DL(CO)) (%). Individuals were 27 with type 1 diabetes: 15 athletes (ADM) and 12 nonathletes (NADM); and 24 healthy individuals: 12 ADM and 12 NADM. Duration of diabetes was 14.6 ± 6.2 and 15.2 ± 6.7 years in ADM and NADM, respectively.

RESULTS

Vo(2 peak) (max) was higher in ADM than in NADM (P < 0.001). The anaerobic threshold was lower in subjects with type 1 diabetes than in control subjects (P < 0.001). FEV1 was lower in ADM than in other groups (NADM, athletes control, and nonathletes control, P < 0.001).

CONCLUSIONS

Aerobic capacity in subjects with type 1 diabetes with programmed exercise is similar to the capacity of normal athletes despite lower anaerobic threshold and FEV1.

Glycemic status affects cardiopulmonary exercise response in athletes with type I diabetes

PURPOSE

This study aimed to (a) examine the influence of type I diabetes on the cardiopulmonary exercise response in trained subjects and (b) determine whether glycemic control affects these responses.

METHODS

The cardiopulmonary responses to maximal incremental cycle ergometry were compared in 12 Ironman triathletes with type I diabetes and 10 age- and sex-matched control subjects without diabetes. Athletes with type I diabetes were then stratified into low- (glycosylated hemoglobin (HbA1c) < 7%, n = 5) and high-HbA1c (HbA1c > 7%, n = 7) groups for comparison. Cardiac output, stroke volume, arterial blood pressure, and calculated systemic vascular resistance along with airway function were measured at rest and during steady-state exercise.

RESULTS

During peak exercise HR, stroke volume and cardiac output were not different between the groups with and without diabetes; however, forced expiratory flow at 50% of the forced vital capacity was lower in subjects with diabetes (P < 0.05). Within the group with diabetes, HbA1c was lower in the low-HbA1c versus high-HbA1c group (6.5 +/- 0.3 vs 7.8 +/- 0.4, respectively; P < 0.05), but training volume was not different. At rest, the low-HbA1c group had greater cardiac output and lower systemic vascular resistance than the high-HbA1c group, and all pulmonary function measurements were greater in the low-HbA1c group (P < 0.05). During peak exercise, the VO2, workload, HR, stroke volume, and cardiac output were greater in the low-HbA1c versus the high-HbA1c group (P < 0.05). In addition, all indices of pulmonary function were higher in the low-HbA1c group (P < 0.05). Finally, within the subjects with diabetes, there was a weak inverse correlation between HbA1c and exercise training volume (r2 = -0.352) and stroke volume (r2 = -0.339). These data suggest that highly trained individuals with type I diabetes can achieve the same cardiopulmonary exercise responses as trained subjects without diabetes, but these responses are reduced by poor glycemic control.

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.

Type 2 diabetes impairs pulmonary function in morbidly obese women: a case-control study

AIMS/HYPOTHESIS

To determine whether the presence of type 2 diabetes and the degree of metabolic control are related to reduced pulmonary function in obese individuals.

METHODS

Seventy-five morbidly obese women (25 with type 2 diabetes [cases]--and 50 without diabetes [controls]) with a history of non-smoking and without prior cardiovascular or respiratory disease were prospective recruited for a case-control study in the outpatient obesity unit of a referral centre. Both groups were closely matched by age, BMI and waist circumference. Pulmonary function test included forced spirometry and static pulmonary volume measurements.

RESULTS

Type 2 diabetic patients showed lower forced expiratory volume at 1 s (FEV1) (mean difference -11.6% of predicted [95% CI -20.4 to -2.8]; p = 0.011), and FEV1/forced vital capacity (FEV1/FVC) ratio (mean difference -4.4% [95% CI -8.1 to -0.7]; p = 0.049), but a greater residual volume (RV) (mean difference 19.5% of predicted [95% CI 10.8-28.3]; p < 0.001). In addition, an obstructive ventilatory pattern was more frequent in diabetic patients. Significant negative correlations between FEV1 and fasting glucose, HbA1c and HOMA insulin resistance (HOMA-IR) were detected. By contrast, RV was positively correlated with fasting glucose, HbA1c and HOMA-IR. Multiple linear regression analyses showed that fasting glucose and HbA1c independently predicted FEV1 and RV.

CONCLUSIONS/INTERPRETATION

The presence of diabetes and the degree of glycaemic control are related to respiratory function impairment in morbidly obese women. Therefore, the impact of type 2 diabetes on pulmonary function should be taken into consideration by those providing care for obese people.

Fatty diabetic lung: altered alveolar structure and surfactant protein expression

Pulmonary dysfunction develops in type 2 diabetes mellitus (T2DM) in direct correlation with glycemia and is exacerbated by obesity; however, the associated structural derangement has not been quantified. We studied lungs from obese diabetic (fa/fa) male Zucker diabetic fatty (ZDF) rats at 4, 12, and 36 wk of age, before and after onset of T2DM, compared with lean nondiabetic (+/+) rats. Surfactant proteins A and C (SP-A and SP-C) immunoexpression in lung tissue was quantified at ages 14 and 18 wk, after the onset of T2DM. In fa/fa animals, lung volume was normal despite obesity. Numerous lipid droplets were visible within alveolar interstitium, lipofibroblasts, and macrophages, particularly in subpleural regions. Total triglyceride content was 136% higher. By 12 wk, septum volume was 21% higher, and alveolar duct volume was 36% lower. Capillary basement membrane was 29% thicker. Volume of lamellar bodies was 45% higher. By age 36 wk, volumes of interstitial collagen fibers, cells, and matrix were respectively 32, 25, and 80% higher, and capillary blood volume was 18% lower. ZDF rats exhibited a strain-specific increase in resistance of the air-blood diffusion barrier with age, which was exaggerated in fa/fa lungs compared with +/+ lungs. In fa/fa lungs, SP-A and SP-C expression were elevated at age 14-18 wk; the normal age-related increase in SP-A expression was accelerated, whereas SP-C expression declined with age. Thus lungs from obese T2DM animals develop many qualitatively similar changes as in type 1 diabetes mellitus but with extensive lipid deposition, altered alveolar type 2 cell ultrastructure, and surfactant protein expression patterns that suggest additive effects of hyperglycemia and lipotoxicity.

The metabolic syndrome, diabetes and lung dysfunction

Sleep-disordered breathing and sleep apnoea are conditions frequently associated with comorbidity, including obesity, diabetes, hypertension, insulin resistance (metabolic syndrome) and cardiovascular disease. The diabetic state (type 1 and type 2 diabetes) may be associated to diminished lung function and, in particular, decreased vital capacity, and the association between chronic obstructive pulmonary disease (COPD) and type 2 diabetes may be due to a shared inflammatory process. Also, the alteration in circulating endothelial progenitor cells found in respiratory disease, the metabolic syndrome and cardiovascular disease reflect a common condition of endothelial dysfunction.

Diminished alveolar microvascular reserves in type 2 diabetes reflect systemic microangiopathy

OBJECTIVE

Alveolar microvascular function is moderately impaired in type 1 diabetes, as manifested by restriction of lung volume and diffusing capacity (DL(CO)). We examined whether similar impairment develops in type 2 diabetes and defined the physiologic sources of impairment as well as the relationships to glycemia and systemic microangiopathy.

RESEARCH DESIGN AND METHODS

A cross-sectional study was conducted at a university-affiliated diabetes treatment center and outpatient diabetes clinic, involving 69 nonsmoking type 2 diabetic patients without overt cardiopulmonary disease. Lung volume, pulmonary blood flow (Q), DL(CO), membrane diffusing capacity (measured from nitric oxide uptake [DL(NO)]), and pulmonary capillary blood volume (V(C)) were determined at rest and exercise for comparison with those in 45 healthy nonsmokers as well as with normal reference values.

RESULTS

In type 2 diabetic patients, peak levels of oxygen uptake, Q and DL(CO), DL(NO), and V(C) at exercise were 10-25% lower compared with those in control subjects. In nonobese patients (BMI <30 kg/m(2)), reductions in DL(CO), DL(NO), and V(C) were fully explained by the lower lung volume and peak Q, but these factors did not fully explain the impairment in obese patients (BMI >30 kg/m(2)). The slope of the increase in V(C) with respect to Q was reduced approximately 20% in patients regardless of BMI, consistent with impaired alveolar-capillary recruitment. Functional impairment was directly related to A1C level, retinopathy, neuropathy, and microalbuminuria in a sex-specific manner.

CONCLUSIONS

Alveolar microvascular reserves are reduced in type 2 diabetes, reflecting restriction of lung volume, alveolar perfusion, and capillary recruitment. This reduction correlates with glycemic control and extrapulmonary microangiopathy and is aggravated by obesity.

The effect of exercise on the absorption of inhaled human insulin via the AERx insulin diabetes management system in people with type 1 diabetes

OBJECTIVE

This study investigated the effect of moderate exercise on the absorption of inhaled insulin via the AERx insulin diabetes management system (iDMS).

RESEARCH DESIGN AND METHODS

In this randomized, open-label, four-period, crossover, glucose clamp study 23 nonsmoking subjects with type 1 diabetes received a dose of 0.19 units/kg inhaled human insulin followed in random order by either 1) no exercise (NOEX group) or 30 min exercise starting, 2) 30 min after dosing (EX30), 3) 120 min after dosing (EX120), or 4) 240 min after dosing (EX240).

RESULTS

Exercise changed the shape of the free plasma insulin curves, but compared with the NOEX group the area under the curve for free plasma insulin (AUC(ins)) for the first 2 h after the start of exercise was unchanged for EX30 and EX240, while it was 15% decreased for EX120 (P < 0.01). The overall insulin absorption during 6 and 10 h after dosing was 13% decreased for EX30 (P < 0.005), 11% decreased for EX120 (P < 0.01), and unchanged for EX240. Exercise did not influence the maximum insulin concentration (Cmax), while the time to Cmax was 22 min earlier for EX30 (P = 0.04). The AUC for the glucose infusion rate (AUC(GIR)) for 2 h after the start of exercise increased by 58% for EX30, 45% for EX120, and 71% for EX240 (all P < 0.02) compared with the NOEX group.

CONCLUSIONS

Thirty minutes of moderate exercise led to unchanged or decreased absorption of inhaled insulin via AERx iDMS and faster Cmax for early exercise. Thus, patients using AERx iDMS can adjust insulin dose as usual independent of time of exercise, but they should be aware of the faster effect if exercising early after dosing.

Lung function changes related to diabetes mellitus

Diabetic microangiopathy targets the lung as it does other organs. Even though respiratory dysfunction in most patients with diabetes is subclinical and rarely the presenting complaint, there are several reasons why pulmonary assessment is important: (1) Pulmonary function testing noninvasively quantifies physiological reserves in a large microvascular bed that is not clinically devastated by diabetes. (2) Subclinical loss of pulmonary reserves becomes overtly debilitating under conditions of stress, such as with aging, chronic hypoxia due to lung disease or high altitude exposure, or volume overload secondary to cardiac and renal failure. (3) Unlike myocardial or skeletal muscle function, pulmonary indices are largely independent of physical fitness. (4) Interpretation of pulmonary function indices is not complicated by secondary sequelae of diabetic end-organ failure or prior therapy. Lung function could provide useful measures of the progression of systemic microangiopathy. (5) Chronic use of inhaled insulin may affect long-term pulmonary function, while preexisting pulmonary dysfunction may alter the absorption and bioavailability of inhaled insulin. This review will discuss the changes in lung function observed in diabetes, their underlying mechanisms, and their physiological and clinical implications.

Decline of neuroadrenergic bronchial innervation and respiratory function in type 1 diabetes mellitus: a longitudinal study

BACKGROUND AND AIM

Type 1 diabetes mellitus complicated by autonomic neuropathy (AN) is characterized by depressed cholinergic bronchomotor tone and neuroadrenergic denervation of the lung. We explored the effects of AN on the rate of decline of pulmonary sympathetic innervation and respiratory function during a 5-year follow-up.

METHODS

Twenty diabetic patients, 11 with AN, were enrolled in 1998 and then followed-up until 2003. During follow-up, glycosylated haemoglobin (HbA1c) was measured every 3 months. In 1998 and 2003 the patients underwent respiratory function tests and a ventilatory scintigraphic study of neuroadrenergic bronchial innervation using 123I-MIBG.

RESULTS

During follow-up 4 patients, all with AN, were lost, and 1 developed AN. Forced vital capacity (FVC), and diffusing capacity of the lung for carbon monoxide (DLCO) showed comparable rates of decrease in patients with and without AN. The yearly decline of forced expiratory volume in 1 s (FEV1) was about double the physiologic rate, in both AN and AN-free patients. The MIBG clearance significantly increased both in patients with AN (T1/2: 118.88 +/- 30.14 min at baseline and 92.10 +/- 24.52 min at the end of follow-up) and without AN (135.14 +/- 17.09 min and 92.68 +/- 13.52 min, respectively), indicating a rapidly progressive neuroadrenergic denervation. The rate of the neuroadrenergic denervation was inversely related to the severity of autonomic dysfunction at baseline (Spearman's rho - 0.62, p = 0.017). Neither respiratory function indexes nor MIBG clearance changes correlated with the overall HbA1c values.

CONCLUSIONS

Neuroadrenergic denervation of the lung parallels the decline of respiratory function indexes in diabetic patients both with and without AN and seems to be independent from the quality of glycemic control.

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.

The diabetic lung: relevance of alveolar microangiopathy for the use of inhaled insulin

The alveolar-capillary network receives the entire cardiac output and constitutes the largest microvascular organ in the body, making it highly susceptible to systemic microangiopathy. Owing to its large reserves, symptoms and disability develop later in the lung than in smaller microvasculature such as the kidney or retina despite a comparable severity of anatomic involvement. Hence, pulmonary impairment in diabetes mellitus is under-recognized. Nonetheless, respiratory autonomic neuropathy and structural derangement of the thorax and lung parenchyma develop in many asymptomatic diabetic patients; the pathophysiology parallels that in other target organs. Even subclinical loss of alveolar microvascular reserves can be quantified noninvasively from lung diffusing capacity and its components (membrane diffusing capacity and alveolar-capillary blood volume) measured at a given cardiac output at rest or during exercise. The alveolar diffusion-perfusion relation tracks the recruitment of microvascular reserves in a manner independent of physical fitness. This article addresses the importance and pathophysiologic basis of diabetic pulmonary involvement, the assessment of diabetic alveolar microangiopathy, and the relevance of this understanding for the emerging use of inhaled insulin.

Comparison of pharmacokinetic and pharmacodynamic properties of single-dose oral insulin spray and subcutaneous insulin injection in healthy subjects using the euglycemic clamp technique

BACKGROUND

Oral insulin spray is a new, noninjectable method of insulin delivery. This system delivers an aerosol of uniform-sized droplets containing regular human insulin at a high velocity into the oropharyngeal cavity for local transmucosal absorption.

OBJECTIVE

The purpose of this study was to compare the pharmacokinetic and pharmacodynamic properties of single-dose oral insulin spray and SC insulin injection in healthy subjects.

METHODS

Healthy male volunteers aged 21 to 25 years participated in this open-label study conducted at the Diabetes Unit, Hadassah-Hebrew University Hospital, Jerusalem, Israel. Subjects presented at 2 visits separated by 7 to 14 days. At both visits, the euglycemic clamp technique was used to maintain a constant blood glucose level. At one visit, subjects received regular human insulin 0.1 U/kg by SC injection. At the other visit, subjects received 15 puffs (150 U) of oral insulin spray. The pharmacokinetic (insulin absorption) and pharmacodynamic (glucose uptake) properties of the drugs were evaluated using blood analyses over the subsequent 360 minutes.

RESULTS

Six volunteers were enrolled (mean [SD] age, 22.8 [1.2] years; mean [SD] body mass index, 23.2 [2.2] kg/m(2)). The mean (SD) baseline-corrected C(max) was significantly higher with oral insulin spray compared with SC insulin (54.0 [20.3] vs 30.8 [6.1] microU/mL; P = 0.028). Mean (SD) T(max) was significantly shorter with oral insulin spray compared with SC insulin (23.3 [5.2] vs 83.3 [42.2] minutes; P = 0.027). The mean (SD) time to maximal metabolic effect (maximum glucose infusion rate [GIR(max)]) (44.2 [8.6] vs 100.0 [35.6] minutes) and late time to half-maximal effect (101.0 [41.0] vs 257.2 [27.8] minutes) were shorter with oral insulin spray compared with SC insulin (both, P = 0.028). The baseline-corrected GIR(max) (6.8 [3.3] vs 6.2 [2.3] mg/kg . min) and glucose consumption (396.7 [178.0] vs 432.1 [226.0] mg/kg) during the 120 minutes after study drug administration were comparable between oral and SC insulin, respectively.

CONCLUSIONS

In this study in a small, selected population of healthy male subjects under euglycemic conditions, oral insulin spray was associated with a higher C(max), shorter T(max), and faster time to peak glucose uptake compared with SC insulin. The short T(max) and the 120-minute duration of effect of oral insulin spray suggest it may be a promising alternative for fulfilling meal-related insulin requirements in persons with diabetes.

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.

Glycemic exposure is associated with reduced pulmonary function in type 2 diabetes: the Fremantle Diabetes Study

OBJECTIVE

To examine prospectively the relationship between diabetes, glycemic control, and spirometric measures.

RESEARCH DESIGN AND METHODS

From a community-based cohort, 495 Europid (i.e., of European descent) patients with type 2 diabetes who had no history of pulmonary disease underwent baseline spirometry between 1993 and 1994. A subset of 125 patients was restudied a mean of 7.0 years later. The main outcome measures included forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), vital capacity (VC), and peak expiratory flow (PEF) corrected for body temperature, air pressure, and water saturation and were expressed either in absolute terms or as percentage-predicted value for age, sex, and height.

RESULTS

Mean percentage-predicted values of each spirometric measure were decreased >10% in the whole cohort at baseline and absolute measures continued to decline at an annual rate of 68, 71, and 84 ml/year and 17 l/min for FVC, FEV1, VC, and PEF, respectively, in the 125 prospectively studied patients. Declining lung function measures were consistently predicted by poor glycemic control in the form of a higher updated mean HbA1c, follow-up HbA1c, or follow-up fasting plasma glucose. In a Cox proportional hazards model, decreased FEV1 percentage-predicted value was an independent predictor of all-cause mortality.

CONCLUSIONS

Reduced lung volumes and airflow limitation are likely to be chronic complications of type 2 diabetes, the severity of which relates to glycemic exposure. Airflow limitation is a predictor of death in type 2 diabetes after adjusting for other recognized risk factors.

Alternative routes of insulin delivery

Attempts at replicating physiological insulin secretion, as a means of restoring the normal metabolic milieu and thereby minimizing the risk of diabetic complications, has become an essential feature of insulin treatment. However, despite advances in the production, purification, formulation and methods of delivery of insulin which have occurred in recent years, this has met with limited success. The current advocacy of intensive insulin therapy regimens involving multiple daily subcutaneous injection places a heavy burden of compliance on patients and has prompted interest in developing alternative, less invasive routes of delivery. To date, attempts to exploit the nasal, oral, gastrointestinal and transdermal routes have been mainly unsuccessful. The respiratory tree, with a large surface area, offers the greatest potential for the delivery of polypeptide drugs and there is renewed interest in administrating insulin by the intrapulmonary route. Current pulmonary drug delivery systems include a variety of pressurized metered dose inhalers, dry powder inhalers, nebulizers and aqueous mist inhalers. Recent clinical studies suggest a possible role for inhaled insulin in fulfilling meal-related insulin requirements in persons with Type 1 and Type 2 diabetes. Most experience with inhaled insulin has been obtained using either dry powder formulation in the Nektar Pulmonary Inhaler/Exubera device (Nektar Therapeutics Inc., San Carlos, CA, Aventis, Bridgewater, NJ, Pfizer, NY) or a liquid aerosol formulation in the AERx Insulin Diabetes Management System (Aradigm Corp., Hayward, CA, NovoNordisk A/S, Copenhagen, Denmark). If long-term safety and efficacy is confirmed, inhalation may become the first non-subcutaneous route of insulin administration for widespread clinical use. Despite overwhelming interest and investment in administering insulin via the oral route, success is not expected in the short term. Attempts at utilizing the buccal mucosa and skin are also continuing. Pancreatic transplantation will remain limited to those patients receiving a kidney transplant and immunotherapy. Islet cell transplantation is at an early though encouraging stage following the availability of new less toxic immunosuppressive agents. True insulin independence will require further advances in the combined fields of cell biology and genetics to ensure freedom from both the need for lifelong administration of insulin and the complications of diabetes.

[Anesthesia in surgery in patients with diabetes mellitus]

Pojava diabetes mellitusa se u zadnjih 30 godina stalno povecava, kako kod odraslih, tako i kod dece. Svetska zdravstvena organizacija procenjuje da ce se broj bolesnika sa diabetes mellitusom povecati sa sadasnjih 150 miliona na 213 miliona do kraja 2010. godine. Dijagnoza diabetesa mellitusa ne postavlja se tesko ukoliko su ispoljeni osnovni simptomi, kao sto su pojacan osecaj zedji, poliurija, polifagija i povecana koncentracija glukoze u krvi. Uzorak krvi se uzima ujutru na prazan stomak. Postupak se ponavlja 2 puta. Granicna vrednost glikemije je 7,8 mmol/l. Ukoliko nije utvrdjena povecana vrednost glukoze u krvi, a postoje ostali simptomi diabetes mellitusa, neophodno je uraditi test opterecenja glukozom.

Insulin improves alveolar-capillary membrane gas conductance in type 2 diabetes

OBJECTIVE

In type 1 diabetes, lung diffusing capacity for carbon monoxide (DL(CO)) may be impaired, and insulin has been shown to be beneficial in cases in which near-normal metabolic control is achieved. An influence of insulin, per se, on the alveolar-capillary membrane conductance is unexplored. We aimed at testing this possibility.

RESEARCH DESIGN AND METHODS

We studied 19 life-long nonsmoking, asymptomatic patients with type 2 diabetes and normal cardiac function, whose GHb averaged 6.2 +/- 0.3% with diet and hypoglycemic drugs. DL(CO) and its subcomponents (alveolar capillary membrane conductance [D(M)] and pulmonary capillary blood volume available for gas exchange [Vc]), vital capacity (VC), forced expiratory volume 1 s (FEV(1)), cardiac output (CO), ejection fraction (EF), pulmonary wedge pressure (WPP), and pulmonary arteriolar resistance (PAR) were determined before and within 60 min after infusion of 50 ml saline + 10 IU of regular insulin or after saline alone on 2 consecutive days (random block design). Glycemia was kept at baseline levels during experiments by dextrose infusion.

RESULTS

Percent of normal predicted DL(CO) averaged 84.2 +/- 7.9% and in 14 patients was <100%. Insulin infusion, not saline alone, improved (P < 0.01) DL(CO) (12%) and D(M) (14%) and raised DL(CO) to 98% of the normal predicted value. There were no variations in VC, FEV(1,) CO, EF, WPP, or PAR, suggesting that the influences of the hormone on gas transfer were not mediated by changes in spirometry, volumes, and hemodynamics of the lung.

CONCLUSIONS

Several cases of type 2 diabetes present with increased impedance to gas transfer across the alveolar-capillary membrane, and hypoglycemic drugs do not prevent this inconvenience. Insulin, independently of the metabolic effects, acutely improves gas exchange, possibly through a facilitation of the alveolar-capillary interface conductance.

Neuroadrenergic denervation of the lung in type I diabetes mellitus complicated by autonomic neuropathy

STUDY OBJECTIVE

To verify whether autonomic neuropathy (AN) complicating type I, insulin-dependent diabetes mellitus affected neuroadrenergic bronchopulmonary innervation.

PATIENTS

Twenty nonsmoking diabetic patients without respiratory diseases were studied: 11 patients with AN (group AN) and 9 patients without AN (control; group C) diagnosed by standardized criteria.

DESIGN

Patients underwent respiratory function tests and ventilatory scintigraphies with (123)I-metaiodobenzylguanidine (MIBG) and with (99m)Tc-diethylenetriaminepenta-acetic acid (DTPA) to assess both bronchopulmonary neuroadrenergic innervation and also permeability of the alveolar-capillary barrier to water-soluble tracers. Rates of pulmonary clearance of the two tracers were computed, and correlates were identified by nonparametric statistics.

SETTING

University hospital.

RESULTS

The AN and C groups had normal respiratory function test results and comparable duration of diabetes and quality of metabolic control. (99m)Tc-DTPA clearance did not distinguish the groups. (123)I-MIBG clearance was faster in the AN group than in the C group (mean +/- SD half-time of the radiotracer time-activity curve [T(1/2)], 116.1 +/- 22.8 min in the AN group vs 139.5 +/- 18.3 min in the C group, p = 0.022), which is consistent with neuroadrenergic denervation in the AN group. (123)I-MIBG clearance was independent from (99m)Tc-DTPA clearance. Faster (123)I-MIBG clearance was significantly associated with worse performance in three of the four autonomic tests.

CONCLUSIONS

Neuroadrenergic bronchopulmonary denervation may occur in diabetic patients with AN despite normal clinical and respiratory function findings. Further research is needed to identify clinical and prognostic implications of these findings.

Peak expiratory flow rate: relationship to risk variables and mortality: the Wisconsin Epidemiologic Study of diabetic retinopathy

OBJECTIVE

To examine correlates of peak expiratory flow rate in people with type 1 diabetes and to evaluate the relationship of peak expiratory flow rate to mortality.

RESEARCH DESIGN AND METHODS

A cohort study that was originally designed to determine the prevalence, incidence, and severity of diabetic retinopathy also provided the opportunity to measure peak expiratory flow rate. This was first measured at a 10-year follow-up and was evaluated in regard to risk factors for microvascular complications of diabetes. Mortality during 6 years of follow-up after the measurement was also ascertained.

RESULTS

In multivariable analysis, peak expiratory flow rate was associated with sex, age, height, BMI, history of cardiovascular disease, pulse rate, duration of diabetes, glycosylated hemoglobin, and end-stage renal disease. Peak expiratory flow rate was significantly associated with survival in categorical analyses. Even after considering age, sex, renal disease, history of cardiovascular disease, respiratory symptoms, duration of diabetes, cigarette smoking, and hypertension, peak expiratory flow rate was still significantly related to survival (hazard ratio 0.61 [95% CI 0.46-0.82]).

CONCLUSIONS

These data indicate that peak expiratory flow rate is associated with risk factors for other complications of diabetes. In addition, peak expiratory flow rate is a significant predictor of survival over even a relatively short period of time (6 years) in patients with younger-onset diabetes.

Is peak expiratory flow rate a predictor of complications in diabetes? The Wisconsin Epidemiologic Study of Diabetic Retinopathy

The Objective of this study was to determine whether peak expiratory flow rate is a predictor of complications of diabetes. Peak expiratory flow rate was measured at the 10-year follow-up (third examination) of a cohort of persons with younger-onset diabetes. The relationships of progression of diabetic retinopathy by two steps, progression to proliferative retinopathy and of incidences of macular edema, sore or ulcers on feet or ankles, lower extremity amputation, proteinuria, and cardiovascular disease 4 years after this examination with respect to peak expiratory flow rate were evaluated. Study procedures including measurements of blood pressure, height and weight, grading of fundus photographs, peak expiratory flow rate, urinalysis, and medical history were performed according to standard protocols. Peak expiratory flow rate was not associated in univariate analyses with progression of retinopathy, incidences of proliferative retinopathy, macular edema or lower extremity amputation, sores or ulcers on feet or ankles, gross proteinuria, or self-reported cardiovascular disease. However, when using multivariable models to include the effects of other risk factors, peak expiratory flow rate was significantly associated with the combined incidences of sores or ulcers on feet and ankles, or lower extremity amputations (OR=0.61, 95% CI 0.42-0.88). These data suggest that peak expiratory flow rate is a predictor of subsequent complications in the lower extremities in those with long duration of younger-onset diabetes. Evaluating this association in an incipient cohort would illuminate whether the relationship we found is likely to be causal.

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.

Glycemic control and cardiopulmonary function in patients with insulin-dependent diabetes mellitus

BACKGROUND

We studied cardiopulmonary function during exercise in young subjects with long-standing insulin-dependent diabetes mellitus (IDDM) who have no clinical cardiopulmonary disease to determine the relationships of aerobic capacity, gas exchange, ventilatory power requirement, and cardiac output to chronic glycemic control.

METHODS

Eighteen subjects with IDDM and 14 normal control subjects were studied. Nine diabetic subjects received twice daily insulin injections and had chronically elevated levels of glycosylated hemoglobin (hyperglycemic group); 9 other diabetic subjects received insulin via continuous infusion pumps and maintained chronic near-normal levels of glycosylated hemoglobin (normoglycemic group). At the end of at least 7 years of regular follow-up, aerobic capacity was determined by cycle ergometry. Lung volume, diffusing capacity, and cardiac output during exercise were measured by a rebreathing technique. Ventilatory power was measured by the esophageal balloon technique.

RESULTS

Maximal work load and oxygen uptake were markedly impaired in chronically hyperglycemic diabetic patients associated with significant restrictions of lung volume, lung diffusing capacity, and stroke index during exercise. Membrane diffusing capacity was significantly reduced at a given cardiac index. The normoglycemic patients consistently showed less impairment than the hyperglycemic patients.

CONCLUSION

Physiologically significant cardiopulmonary dysfunction develops in asymptomatic patients with long-standing IDDM. Chronic maintenance of near-normoglycemia is associated with improved cardiopulmonary function.