Prediabetic, Diabetic CF Patients See Positive Effect From Insulin Therapy

Improvements were seen after one year of treatment in small Italian study

Patricia Valerio, PhD avatar

by Patricia Valerio, PhD |

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A year of insulin treatment improves nutritional status and respiratory function in cystic fibrosis (CF) patients with diabetes, according to a study in Italy.

In addition, CF patients treated with insulin at an early stage of abnormal blood sugar levels have reduced hospital admissions due to respiratory infections.

“Therefore, adequate management of CF patients with alterations in [sugar] metabolism could have a positive impact on their overall clinical condition,” the researchers wrote.

The study, “Positive impact of insulin treatment on clinical trend in cystic fibrosis patients: a retrospective study,” was published in the journal Acta Biomedica.

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Despite marked increases in survival due to recent treatment advances, a higher incidence of long-term complications has been observed in CF, representing a key point in managing this patient population.

One such complication, an alteration in glucose (sugar) metabolism, is frequently linked to CF progression. Impaired glucose tolerance, meaning an impairment in how the body handles glucose, has been associated with cells’ inability to respond to insulin, called insulin resistance. That is related to worse clinical status, malnutrition, and impaired lung function.

CF-related diabetes (CFRD) is known to occur in 40% to 50% of patients. Its prevalence increases by 5% for patients older than 10 and 9% for those older than 20.

The onset of diabetes worsens the clinical condition of CF patients. Among changes in the pancreas, where insulin is produced, this also causes insulin deficiency. Evidence is still lacking for how insulin deficiency affects hospital admissions for respiratory infections.

The study and its results

Researchers in Italy have now studied the impact of insulin treatment in CFRD patients versus those in the early stages of glucose alteration. The groups were compared at the beginning of therapy and again one year later.

“An open question in the scientific community is when to start treating these patients. Some studies are favorable to the early beginning of therapy, but there is still a debate,” the team wrote.

Researchers assessed the participants’ body mass index (BMI, a measure of body fat), respiratory function, and the number of hospital admissions for respiratory infections.

The study included 17 patients overall, plus a 17-person control group. There was an insulin treatment group with nine prediabetic patients (meaning high blood sugar levels, but not high enough to be considered diabetes), of which seven were male and two were female, with a mean age of 21.7. Eight participants had CFRD; three were male and five were female, with a mean age of 26.1. Seven of these 17 patients had the F508del mutation, the most CF-causing mutation, in both CFTR gene copies.

BMI results showed a significant increase, considered positive, after one year of insulin treatment in both prediabetic and CFRD groups. In contrast, BMI significantly decreased at the time in the control group.

At baseline (study start), measures of lung function were lower in the insulin treatment group compared with controls. These differences were still observed after one year of therapy, though the gap was smaller.

The insulin treatment group showed a significant improvement in the maximum air flow out of the lungs, particularly the CFRD subgroup. In contrast, no such improvement was found in the control group.

As for episodes of respiratory infections leading to hospital admissions, only the treated prediabetic patients showed a significant decrease in hospital admissions.

Overall, the results showed that weight gain and lung function were the parameters with better response to insulin treatment in CFRD patients, whereas prediabetic patients responded better in their reduction of hospital admissions due to respiratory infections.

The positive insulin effect on body weight and respiratory function in CFRD patients “reinforces the hypothesis of their indirect connection because better nutritional status could correlate with the increased strength of the patients, and therefore with a better performance of the expiring muscles,” the researchers noted.

In addition, the study suggests the importance of early monitoring of sugar levels and early insulin treatment in CF patients.

“A multicenter trial would be useful to define and standardize modalities and clinical indications of early insulin treatment in prediabetic CF patients.” the research team concluded.

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