Declining incidence of severe retinopathy and persisting decrease of nephropathy in an unselected population of Type 1 diabetes-the Linköping Diabetes Complications Study

Abstract

Aims/hypothesis: In a previous study conducted over the last decades we found a decreased incidence of nephropathy but unchanged incidence of severe retinopathy among patients with Type 1 diabetes diagnosed in childhood and with 20 years duration of diabetes. The aim of our current study was to investigate the incidence 5 to 10 years later in the same population.

Methods: We studied all 269 patients in whom Type 1 diabetes was diagnosed in childhood between 1961 and 1985 in a district in southeastern Sweden. Ninety-one percent were monitored for retinopathy until at least 1997 and 95% were monitored for nephropathy. Severe retinopathy was defined as laser-treated retinopathy and nephropathy as persistent proteinuria. Survival analysis was used and the patients divided into five cohorts according to the time of onset of diabetes.

Results: The cumulative proportion of severe retinopathy had declined ( p=0.006). After 25 years it was 47% (95% CI 34-61), 28% (15-40) and 24% (12-36) in the cohorts 1961 to 1965, 1966 to 1970 and 1971 to 1975 respectively. After 30 years it was 53% (40-66) and 44% (28-59) in the oldest cohorts. The cumulative proportion of nephropathy after 25 years duration was 30% (18-42), 8% (1-16) and 13% (4-23) in the cohorts 1961 to 1965, 1966 to 1970 and 1971 to 1975 respectively. After 30 years, it was 32% (20-44) and 11% (2-20) for the oldest cohorts ( p<0.0001).

Conclusions/interpretation: In an unselected population with Type 1 diabetes diagnosed in childhood, modern diabetes care markedly reduced the incidence of severe retinopathy and nephropathy.