O diabetes melito na fibrose cística: uma comorbidade cada vez mais freqüente

Importance of screening with oral glucose tolerance test for early diagnosis of cystic fibrosis-related diabetes mellitus

OBJECTIVES

To evaluate (a) the prevalence of cystic fibrosis-related diabetes mellitus (CFRD) in a non-Caucasian population treated in a University Hospital in São Paulo, Brazil; and (b) if annual screening of patients with cystic fibrosis (CF) ≥ 10 yr of age, with oral glucose tolerance test (OGTT), resulted in early detection of CFRD.

SUBJECTS AND METHODS

A cross-sectional study was performed with retrospective/prospective analysis of CF patients ≥10 yr of age. Various parameters were analyzed. Patients previously diagnosed with CFRD had their parameters collected at the time of diabetes diagnosis; others were submitted to annual OGTTs, with the parameters collected at the time of their last OGTT.

RESULTS

A total of 60 subjects [29 females/31 males; mean age 19.1 yr (±7.6)] were analyzed. In our group of CF patients, we found that 30% had CFRD, 26.7% had altered response to OGTT, and 43.3% had normal glucose tolerance. Analysis of those patients with CFRD showed that the mean age at the time of diagnosis of CFRD, in patients diagnosed by OGTT screening, was 13.5 yr (±2.9) vs. 22.3 yr (±5.4) among those previously diagnosed by clinical suspicion (p < 0.001).

CONCLUSIONS

The prevalence of CFRD in our patients is high, similar to the data from Caucasian populations, and significantly higher than previously reported in Brazil. Screening with OGTT resulted in earlier diagnosis of CFRD by 8 yr. These data may help convince national CF centers that CFRD is frequent, and that screening should be mandatory.

Update on diagnosis and monitoring of cystic fibrosis-related diabetes mellitus (CFRD)

Cystic fibrosis (CF) is the most common recessive autosomal disease among Caucasian. Children with CF have benefitted from advances in medical and nutritional treatments, and this can be gleaned from the improvement in the survival of these patients. The increase in the survival rate brought with it the appearance of co-morbidities related to CF. Nowadays cystic fibrosis-related diabetes (CFRD) is considered the most common complication associated with CF. It can appear as early as infancy or adolescence, and its prevalence can be as high as 50% in adult patients. Because of its high prevalence, difficulties in early detection and the risks involved, in recent years several studies and consensuses have focused on this condition, adding information about the epidemiology, pathophysiology, prognosis and treatment of CFRD. The main aspects of these new concepts, as well as the current recommendations for its diagnosis and follow-up, will be presented in this study.

Low prevalence of glucose intolerance in racially mixed children with cystic fibrosis

OBJECTIVE

To evaluate glucose tolerance in racially mixed Brazilian youth with cystic fibrosis (CF).

METHODS

Cross-sectional study conducted between August and September 2007, at a reference service for CF, evaluating: glycated hemoglobin (HbA1c), blood glucose, and insulin levels, before and 2 h after a glucose overload.

RESULTS

There were 46 patients aged between 6 yr and 16 yr and 2 months (median: 9 yr and 10 months) of whom 64% were boys. Of these, 26% were Whites; 54.4% Mulattoes; and 19.6% Blacks. HbA1c was normal in all patients. Only one participant (12-yr old) had glucose intolerance. Insulin levels ranged from 1 to 23 µIU/mL (median: 4.5 µIU/mL) at baseline and from 3.2 to 192.1 µIU/mL (median: 11 µIU/mL) after a glucose overload. Insulin resistance evaluated by the HOMA index, stratified by sex and age, was present in three patients. The ΔF508 mutation was present in only 4.3% of the sample, all of them being heterozygous.

CONCLUSIONS

The low prevalence of carbohydrate intolerance in this population is probably a result of their young age. Another possibility is the low frequency of the ΔF508 mutation. Although not conclusive, these data suggest that in addition to age, the genotype:phenotype ratio may influence the development of glucose intolerance in patients with CF.