V. Boudreau

Glycated hemoglobin cannot yet be proposed as a screening tool for cystic fibrosis related diabetes

With improved life expectancy of cystic fibrosis (CF) patients, CF-related diabetes (CFRD) has become a major complication. The oral glucose tolerance test (OGTT) is the standard test to detect it. However, the use of OGTT is controversial, in addition to being a burden for patients and the treatment team. Research to find alternative ways of testing is ongoing. While some propose that glycated hemoglobin (HbA1c) may be an effective alternative, our past results suggest otherwise. A new analysis involving the OGTT and HbA1c values of 207 patients, between 2004 and 2015, proposes that the threshold of a lower value of HbA1c of ≥5.8%(39.9 mmol/mol) gives a sensitivity of 68.2% and a specificity of 60.5%. With such sensitivity to identify patients in need of an OGTT, 31.8% of CFRD diagnosis would be missed if the suggested HbA1c value of ≥5.8% was used as a screening tool to identify patients in need of OGTTs. Considering our results, we believe the HbA1c does not possess the characteristics of a suitable screening test for CFRD.

Screening for Cystic Fibrosis-Related Diabetes: Matching Pathophysiology and Addressing Current Challenges

Nearly 50% of adult patients with cystic fibrosis (CF) have diabetes. The occurrence of CF-related diabetes (CFRD) is preceded and is associated with deterioration of lung function and nutritional status. Microvascular complications can occur, but the main cause of death is respiratory failure rather than cardiovascular causes as in type 1 or type 2 diabetes. Because other methods such as glycated hemoglobin (A1C) levels are less sensitive in patients with CF, the recommended screening test is the oral glucose tolerance test (OGTT) with a 75 g glucose dose. However, OGTT is poorly suited for patients with CF, who are already facing a high disease-care burden, and appropriate CF-glucose cut-off for diagnosis and prognosis are also questioned. Thus, alternative screening methods are compared to the classical test (2-hour OGTT), including shorter OGTTs and continuous glucose monitoring. Moreover, many challenges complicate the screening for diabetes such as the complex medical care time for a patient, which is reflected by low adherence to screening tests. The best screening test should take into account the particularities of CFRD and the complexity of the CF medical care.

Variation of glucose tolerance in adult patients with cystic fibrosis: What is the potential contribution of insulin sensitivity?

BACKGROUND Reduced insulin secretion is a key factor to explain high prevalence of glucose intolerance in patients with cystic fibrosis (CF). However, the role of insulin sensitivity remains unclear. The aim of this study is to investigate the association of insulin secretion and sensitivity with the evolution of glucose tolerance. METHODS A total of 152 patients without known diabetes from the Montreal CF cohort underwent two 2-h oral glucose tolerance tests (OGTT) at baseline and again after 21.2±5.5months. Pulmonary function and anthropometric measurements were also collected at each visit. At both visits, based on their OGTT results, patients were categorized in glucose tolerance groups (normal glucose tolerance, impaired glucose tolerance or CF-related diabetes) and stratified in 3 groups according to the variation of their glucose tolerance: stable, improved or deteriorated. RESULTS At baseline, patients in the deteriorated group had a better sensitivity to insulin than those in the improved group (P=0.029). At follow-up glucose tolerance remained stable in 55.3%, improved in 14.5% and deteriorated in 30.3% of patients. During follow-up, insulin secretion remained stable in all 3 groups. While insulin sensitivity remained stable in patients without changes in glucose tolerance it worsened in patients who deteriorated glucose tolerance (P<0.001) and improved in patients who improved their glucose tolerance (P=0.003). CONCLUSION In a context of significantly reduced insulin secretion, variations of insulin sensitivity are associated with variations of glucose tolerance in adult patients with CF.

Association between glucose intolerance and bacterial colonisation in an adult population with cystic fibrosis, emergence of Stenotrophomonas maltophilia

BACKGROUND Diabetes is common in cystic fibrosis (CF). Glucose can be detected in the airway when the blood glucose is elevated, which favours bacterial growth. We investigated the relationship between dysglycemia and lung pathogens in CF. METHODS Cross-sectional and prospective analysis of CF patients (N=260) who underwent a 2h-oral glucose tolerance test. Clinical data was collected. RESULTS Stenotrophomonas maltophilia (S. maltophilia) was the sole bacteria increased in dysglycemic (AGT: 20.2%, CFRD: 21.6%) patients compared to normotolerants (NGT: 8.7%). S. maltophilia positive patients with dysglycemia had more pulmonary exacerbation events compared to NGTs (1.22 vs 0.63, P=0.003). The interaction between S. maltophilia colonisation and glucose tolerance status significantly increases the risk of lower lung function (P=0.003). Its growth was not affected by the evolution of the glucose tolerance after three years follow-up. CONCLUSION Prevalence of S. maltophilia was higher in dysglycemic patients, supporting the idea that S. maltophilia is a marker of disease severity in CF.

Diabète de type 1 et surplus de poids : au-delà des glucides

Resume Une augmentation de la prevalence de surpoids et de complications cardio-metaboliques, possiblement secondaire a une faible adhesion a de saines habitudes de vie, a ete observee chez les patients atteints de diabete de type 1, ce qui pourrait majorer leur risque cardiovasculaire. Tandis que la qualite alimentaire des patients est sous-optimale, les recommandations nutritionnelles sont concentrees sur le comptage des glucides. Des etudes sont necessaires pour etablir des recommandations pour ameliorer la qualite alimentaire et la gestion du poids corporel.

Le dépistage du diabète secondaire à la mucoviscidose

Resume Pres de 50% des patients adultes atteints de mucoviscidose (MV) sont diabetiques. La survenue du diabete secondaire a la MV (DSMV) est precedee, et associee, a une deterioration de la fonction pulmonaire et de l’etat nutritionnel. Les complications microvasculaires peuvent survenir, mais la cause de mortalite est l’insuffisance respiratoire, plutot que les causes cardiovasculaires. Le test de depistage recommande est l’hyperglycemie provoquee par voie orale (HGPO), mais comme il est peu adapte au suivi medical du DSMV, des methodes alternatives sont explorees.