Of genes and men: the alternative view of sex differences in cystic fibrosis: response to Sims et al. and Milla et al.

retinopathy) (3). Our data relate to patients 20 years old and cannot be generalized to the adult population. Stefánsson states that in Iceland, no patient progressed from “no retinopathy” to “vision-threatening retinopathy” within 2 years. However, since collecting the original data (1990–2002), we have been informed of two former patients who had rapid progression from level 31 and level 45 retinopathy to blindness in 2 years. These patients were 21 and 23 years old when blindness occurred (therefore outside of our study group), and both had significant risk factors for retinopathy (persistently high HbA1c and diabetes duration 17 years). Stefánsson describes a decrease in legal blindness due to retinopathy in the Icelandic population. Although this may be due to improved management of retinopathy, it may also indicate a reduction in retinopathy due to intensive insulin therapy. This would be in keeping with the trend in our population, in which the incidence of retinopathy has decreased over the last decade from 49 to 24% in patients of 8 years’ diabetes duration (4). However, despite the declining incidence of retinopathy in our population, adolescents should be advised of the serious and real risk of blindness due to diabetic retinopathy. Indeed, blindness occurred in the two patients mentioned above in 2003 and 2004. Clinicians must not underestimate the risk of future blindness from retinopathy for adolescents.