Relationship between diabetic retinopathy, microalbuminuria and overt nephropathy, and twenty-year incidence follow-up of a sample of type 1 diabetic patients.

Purpose: To determine the incidence and relationship of diabetic retinopathy (DR), microalbuminuria and overt nephropathy (ON).

Method: A 20-year prospective study, in a cohort of 110 consecutive type 1 diabetes mellitus (DM) patients, without diabetic retinopathy or microalbuminuria at enrolment in 1990.

Results: The 20-year incidence of any DR was 70.91%, microalbuminuria 42.72%, and ON was 23.63%. Regarding the risk factors: pre pubertal age at diagnosis was significant for DR and ON, LDL-cholesterol and CT/HDL-cholesterol were significant for DR but not for microalbuminuria or ON. The relationship between DR and ON demonstrated that DR was a significant risk factor for ON, but ON was significant for sight-threatening DR. At the end of the study, two major groups of patients were formed: patients with DR only and patients with DR and ON. For the development of only DR we can assume that the most important risk factor is the duration of DM, followed by the high levels of HbA1c, pre-pubertal age at onset, and arterial hypertension; and for the development of ON and DR simultaneously, risk factors are higher levels of HbA1c, arterial hypertension, DM duration and pre-pubertal age at onset.

Conclusions: In the current study, two major groups of patients have been formed, those who developed only DR and those who developed DR and ON. For the former, incidence increased as DM duration increased, and for the latter incidence appeared to be closely related to levels of HbA1c.