"In the European multicentre study of 3,250 people with IDDM attending hospital clinics, background retinopathy was found in 35.9 per cent and proliferative retinopathy in 10.3 per cent. Its prevalence increased with duration of diabetes. Background retinopathy was found in about seven per cent of those who had had diabetes for less than five years, but rose steeply between five and 15 years duration, reaching a plateau of 82 per cent after 20 years. Proliferative retinopathy was virtually absent before ten years duration, after which it rose steadily to reach a prevalence of 37 per cent after 30 or more years of diabetes. Higher prevalences were found in a widely quoted community study carried out in Wisconsin, in the USA. After 15 years of diabetes, 98 per cent of people with IDDM had some degree of retinopathy. Proliferative retinopathy was present in 56 per cent of
those with IDDM for 20 years or more.
As many as 18 per cent of people with NIDDM have diabetic retinopathy at the time of diagnosis, according to the UK Prospective Diabetes Study. Many people with this type of diabetes may well have had the condition for several years before it was actually diagnosed. Further data from the Wisconsin study indicate that, as in IDDM, prevalence of retinopathy increases with duration of NIDDM: 23 per cent of those taking insulin and 20 per cent of those not taking insulin had some degree of retinopathy during the first two years after diagnosis, rising to about 87 per cent and 53 per cent respectively after 20 years of diabetes. Proliferative retinopathy was again rare in the first few years, rising to a prevalence of 25 per cent in those taking insulin and 10 per cent in those not after 20 years of diabetes. These data relate to the USA, and absolute figures for the UK may differ, since the European multicentre study of people with IDDM suggests that the prevalence of retinopathy in people with IDDM is lower in European countries than in the USA."
p12 of 18, from Diabetes in the United Kingdom, 1996, referring to 1984 studies
Klein, R., Klein, B.E., Moss, S.E., Davis, M.D. and DeMets, D.L. The Wisconsin Epiderniologic Study of Diabetic Retinopathy. II. Prevalence and risk of diabetic retinopathy when age at diagnosis is less than 30 years. Archives of Ophthalmology 1984, 102: 520-526
Klein, R., Klein, B.E., Moss, S.E., Davis, M.D. and DeMets, D.L. The Wisconsin Epiderniologic Study of Diabetic Retinopathy. III. Prevalence and risk of diabetic retinopathy when age at diagnosis is 30 or more years. Archives of Ophthalmology 1984, 102: 527-532
"If [Type 1] diabetes is diagnosed in infants or toddlers and the prepubertal duration of diabetes is very long, the patients seem to be protected against diabetic retinopathy." - small study (105 patients), interesting article though.
Infant and Toddler Type 1 DiabetesComplications After 20 Years' Duration (2012) Diabetes Care. 2012;35(4):829-833.
In the text below replace IDDM with 'Type 1 diabetes' and NIDDM with 'Type 2 diabetes' (they stand for insulin-dependent diabetes mellitus and non-insulin-dependent diabetes mellitus respectively).