In animals, glucose concentrations are 3-20 times lower in lung lining fluid than in plasma. In humans, glucose concentrations are normally low (<1 mmol/l) in nasal and bronchial fluid, but they are elevated by inflammation or hyperglycemia. Furthermore, elevated bronchial glucose is associated with increased respiratory infection in intensive care patients. Our aims were to estimate normal glucose concentrations in fluid from distal human lung sampled noninvasively and to determine effects of hyperglycemia and lung disease on lung glucose concentrations. Respiratory fluid was sampled as exhaled breath condensate, and glucose was measured by chromatography with pulsed amperometric detection. Dilution corrections, based on conductivity, were applied to estimate respiratory fluid glucose concentrations (breath glucose). We found that breath glucose in healthy volunteers was 0.40 mmol/l (SD 0.24), reproducible, and unaffected by changes in salivary glucose. Breath-to-blood glucose ratio (BBGR) was 0.08 (SD 0.05). Breath glucose increased during experimental hyperglycemia (P < 0.05) and was elevated in diabetic patients without lung disease [1.20 mmol/l (SD 0.69)] in proportion to hyperglycemia [BBGR 0.09 (SD 0.06)]. Breath glucose was elevated more than expected for blood glucose in cystic fibrosis patients [breath 2.04 mmol/l (SD 1.14), BBGR 0.29 (SD 0.17)] and in cystic fibrosis-related diabetes [breath 4.00 mmol/l (SD 2.07), BBGR 0.54 (0.28); P < 0.0001]. These data indicate that 1) this method makes a biologically plausible estimate of respiratory fluid glucose concentration, 2) respiratory fluid glucose concentrations are elevated by hyperglycemia and lung disease, and 3) effects of hyperglycemia and lung disease can be distinguished using the BBGR. This method will support future in vivo investigation of the cause and effect of elevated respiratory fluid glucose in human lung disease.

BG> or =8 mmol L(-1) predicted elevated AG concentrations in CF, at least in nasal secretions. CFRD patients spent approximately 50% day with BG>airway threshold, implying persistently elevated AG concentrations. Further studies are required to determine whether elevated airway glucose concentrations contribute to accelerated pulmonary decline in CFRD.

Cystic fibrosis (CF) is an inherited disorder associated with severe inflammation and repeated bacterial infection and colonization in the lung. Airway epithelium is involved in defence against bacteria, but this system may be defective in CF. Pro‐inflammatory cytokines can stimulate the expression of inducible nitric oxide synthase (iNOS), an enzyme generating nitric oxide, which functions as an important mediator in host defence mechanisms. To understand better the poor resistance to infections in the CF lung, the expression of the iNOS gene was investigated in explanted lungs from patients with cystic fibrosis (n‐13), bronchiectasis (n‐3), emphysema (n‐14), and in normal lungs (n‐8). In addition, bronchial epithelial cell lines were examined to study iNOS gene expression in vitro. Strong immunoreactivity for iNOS was seen in inflammatory cells and bronchial epithelium in all the diseased lungs, except for bronchial epithelium in CF. Quantitative analysis showed a significant reduction in the area of epithelium immunostained in CF [CF 6·8±1·6 (%±SEM); emphysema 18·2±2·8; normal 9·6±0·8, P<0·01], regardless of steroid treatment. These results were supported by in situ hybridization of iNOS mRNA, which showed a pattern of gene expression in CF, emphysema, and normal lung which paralleled that of protein immunoreactivity. Stimulation with cytokines (IL‐1β, TNF‐α, and IFN‐γ) increased the expression of iNOS mRNA detected by reverse transcriptase‐polymerase chain reaction (RT‐PCR) in cultures of normal (16HBE14o−), but not CF (CFBE41o−, with ΔF508 CFTR mutation) epithelial cells. Expression of iNOS in inflammatory cells suggests that the gene is normal in CF. Absence of iNOS from bronchial epithelium may be due to low expression of the gene resulting from abnormalities in the signalling system that normally causes induction, such as cytokine receptors, second messengers or transcription factors. The resulting deficiency of the nitric oxide defence system may be relevant to the susceptibility of CF patients to pulmonary bacterial colonization. © 1998 John Wiley & Sons, Ltd.

The prevalence of cystic fibrosis-related diabetes (CFRD) and glucose intolerance (IGT) has risen dramatically over the past 20 years as survival has increased for people with cystic fibrosis (CF). Diabetes is primarily caused by pancreatic damage, which reduces insulin secretion, but glucose tolerance is also modified by factors that alter insulin resistance, such as intercurrent illness and infection. CFRD not only causes the symptoms and micro and macrovascular complications seen in type 1 and type 2 diabetes in the general population, but also is associated with accelerated pulmonary decline and increased mortality. Pulmonary effects are seen some years before the diagnosis of CFRD, implying that impaired glucose tolerance may be detrimental. Current practice is to screen for changes in glucose tolerance by regular measurement of fasting blood glucose, by oral glucose tolerance test or a combination of these approaches with symptom review and measurement of HbA1C. Treatment is clearly indicated for those with CFRD and fasting hyperglycaemia to control symptoms and reduce complications. As nutrition is critical in people with CF to maintain body mass and lung function, blood glucose should be controlled in CFRD by adjusting insulin doses to the requirements of adequate food intake and not by calorie restriction. It is less clear whether blood glucose control will have clinical benefits in the management of patients with CFRD without fasting hyperglycaemia or with impaired glucose tolerance and further studies are required to establish the best treatment for this patient group.

Objective To describe the maternal and fetal outcomes of pregnancies in women with cystic fibrosis.Design Retrospective study.Setting Single obstetric hospital and adult cystic fibrosis centre.Methods Retrospective case-note review of pregnant women with cystic fibrosis referred for antenatal care and delivery.Main outcome measures Maternal and fetal outcomes, mode of delivery, lung function and pregnancy complications.Results Forty-eight pregnancies were studied in 41 women. There were two miscarriages, 44 singleton pregnancies and two sets of twins. All babies were liveborn and survived. The mean gestational age at delivery was 35.9 ± 3.3 weeks. There were no fetal abnormalities or terminations of pregnancy. The median birthweight centile was 31.9 (interquartile range 14.9-55.6). Twentyfive (52.1%) of the women had pancreatic insufficiency and 17 (35.4%) required insulin. There was a positive correlation between booking predicted forced expiratory volume in 1 second (FEV 1 ) and gestational age at delivery (P < 0.01). Women with FEV 1 60% were more likely to deliver earlier and by caesarean section compared with women with FEV 1 >60% (35.0 ± 3.2 weeks versus 37.1 ± 3.0 weeks; P = 0.02 and 75.0% versus 25.0%; P = 0.01). Three of the seven women with an FEV 1 <40% died within 18 months of delivery. Four of the eight women with FEV 1 40-50% died between 2 and 8 years after delivery.Conclusion Pregnancy for women with cystic fibrosis is possible and results in favourable maternal and fetal outcomes, but the incidence of preterm delivery and caesarean section is increased. Women with pre-existing poor lung function should be counselled antenatally to ensure that they understand the implications of their shortened life-expectancy and parenthood.