Cystic fibrosis-related diabetes: current trends in prevalence, incidence, and mortality

Abstract

Objective: Cystic fibrosis (CF)-related diabetes (CFRD) diagnosis and management have considerably changed since diabetes was first shown to be associated with a poor prognosis in subjects with CF. Current trends in CFRD prevalence, incidence, and mortality were determined from a comprehensive clinical database.

Research design and methods: Data were reviewed from 872 CF patients followed at the University of Minnesota during three consecutive intervals: 1992-1997, 1998-2002, and 2003-2008.

Results: CFRD is currently present in 2% of children, 19% of adolescents, and 40-50% of adults. Incidence and prevalence are higher in female subjects aged 30-39 years; otherwise, there are no sex differences. In younger individuals, CFRD without fasting hyperglycemia predominates, but fasting hyperglycemia prevalence rises with age. CFRD mortality has significantly decreased over time. From 1992-1997 to 2003-2008, mortality rate in female subjects dropped by >50% from 6.9 to 3.2 deaths per 100 patient-years and in male subjects from 6.5 to 3.8 deaths per 100 patient-years. There is no longer a sex difference in mortality. Diabetes was previously diagnosed as a perimorbid event in nearly 20% of patients, but of 61 patients diagnosed with diabetes during 2003-2008, only 2 died. Lung function but not nutritional status is still worse in CF patients with diabetes compared with those without diabetes. Nutritional status and pulmonary status are similar between patients without fasting hyperglycemia and those with fasting hyperglycemia.

Conclusions: Previously noted sex differences in mortality have disappeared, and the gap in mortality between CF patients with and without diabetes has considerably narrowed. We believe that early diagnosis and aggressive treatment have played a major role in improving survival in these patients.

Figure 1

Current prevalence of CFRD in the 527 patients actively followed at the University of Minnesota, 15 September 2008. A: CFRD total (■), CFRD with fasting hyperglycemia (▨), and CFRD without fasting hyperglycemia (□) by decade of age. B: CFRD total men (■) versus women (□) by decade of age. The number of total subjects (with and without diabetes) in each age-group is noted. *P = 0.02, men vs. women.

Figure 2

The University of Minnesota CFRD incidence per 100 patient-years by sex and age decade 2003–2008. Sample sizes for the incidence rates are shown below the figure.

Figure 3

The University of Minnesota CFRD and CF mortality per 100 patient-years by sex and age decade over three time periods: 2003–2008, 1998–2002, and 1992–1997. CF patients with diabetes (DM) are shown with solid lines, while CF patients without diabetes are shown with dashed lines. Zero rates estimated from <10 patients are not shown. The gap in mortality between those with and those without diabetes has diminished over these time periods, and the sex difference in mortality has disappeared in the most current analysis.