Does β-Cell Autoimmunity Play a Role in Cystic Fibrosis–Related Diabetes? Analysis Based on the German/Austrian Diabetes Patienten Verlaufsdokumentation Registry

Abstract

Research on β-cell autoimmunity in cystic fibrosis (CF)-related diabetes (CFRD) is still rare. We aimed to analyze the frequency of β-cell autoimmunity and the influence on age at diabetes onset, insulin requirement, type of insulin therapy, and hypoglycemic or ketoacidotic events in patients with CFRD compared with antibody-negative patients with CFRD in the Diabetes Patienten Verlaufsdokumentation (DPV) registry. We analyzed data of 837 patients with CFRD in the German/Austrian DPV database by multivariable mixed-regression modeling. In our cohort, 8.5% of patients with CFRD (n = 72) were found to be β-cell antibody positive. There was a female preponderance in this patient group: 65.3 vs. 57.6%. Diabetes onset (median [interquartile range]) was earlier (14.00 [10.15-15.90] vs. 16.10 [13.50-21.20] years; P < 0.005), and insulin dose/kg body weight was higher (0.95 [0.61-1.15] vs. 0.67 [0.33-1.04] IU/kg; P < 0.05). There were also differences in the type of insulin treatment. Insulin pump therapy was used significantly more often in patients with CFRD with β-cell autoimmunity (18.2 vs. 6.4%; P < 0.05). The differences for multiple daily injections (ICT) and conventional therapy (CT) were not significant (ICT: 67.7 vs. 79.0%; CT: 15.2 vs. 14.6). Oral antidiabetic agents were rarely used in both groups. Rate of severe hypoglycemia with coma and rate of ketoacidosis were higher in antibody-positive patients (hypoglycemia with coma: 8.0 vs. 1.4, P < 0.05; ketoacidosis: 9.3 vs. 0.9, P < 0.05). Presence of β-cell autoantibodies in our cohort of patients with CFRD (8.5%) appeared to be greater than in the general population and was associated with female sex, earlier onset of diabetes, and higher insulin requirement. Insulin pump therapy was used significantly more often in patients with β-cell antibodies. Severe hypoglycemia and ketoacidosis were significantly more frequent in CFRD with β-cell autoimmunity compared with β-cell antibody-negative patients with CFRD.