With increasing life expectancy of patients with cystic fibrosis (CF), secondary diabetes becomes more prevalent. It appears to be the most common co‐morbidity in persons with cystic fibrosis. Therefore, the objective of our study was to describe characteristics of cystic fibrosis‐related diabetes compared with type 1 and 2 diabetes (T1DM/T2DM) in adults.

Data from 218 436 patients >18 years with cystic fibrosis (n = 401), T1DM (n = 32,409) or T2DM (n = 185 626) in the multicenter Diabetes‐Patienten‐Verlaufsdokumentation or prospective documentation of diabetes patients registry were analysed.

Diabetes onset [median (interquartile range)] in cystic fibrosis [18.70 (15.50–25.30) years] was between T1DM [16.40 (10.50–31.80) years] and T2DM [58.50 (48.80–68.00) years], with female preponderance. Body mass index (BMI) and glycosylated haemoglobin (HbA_1c) were lowest (19.6 [18.1–21.5] kg/m²)/50 mmol/mol (6.73%) versus T1DM (24.4 [22.1–27.4])/62 mmol/mol (7.83%) vs. T2DM (29.6 [26.1–33.9])/54 mmol/mol (7.06%); all p < 0.01. A total of 78.6% of cystic fibrosis patients with diabetes received insulin. Insulin dose (0.74 IE/kg bodyweight) was not significantly different from T1DM (0.73) and T2DM (0.76). Frequency of vascular complications, adjusted for confounding effects, across the groups was different: Hypertension (CFRD 16.1% vs. T1DM 24.0% vs. T2DM 32.2%; all p < 0.01), retinopathy (CFRD 10.7% vs. T1DM 10.4% vs. T2DM 10.5%, not significant), nephropathy (CFRD 25.2% vs. T1DM 17.2% vs. T2DM 24.7%; only T1DM/T2DM; p < 0.01).

CFRD is a uniquely complex entity with clear differences from T1DM and T2DM in adults. Copyright © 2013 John Wiley & Sons, Ltd.