Subclassification of preproliferative diabetic retinopathy and glycemic control:: Relationship between mean hemoglobin A1C value and development of proliferative diabetic retinopathy

Purpose: We evaluated the relationship between long-term glycemic control and the proportion of patients developing proliferative diabetic retinopathy (PDR) among cases with mild type preproliferative diabetic retinopathy (PPDR). Methods: The relationship was evaluated between the mean hemoglobin A(1C) (HbA(1C)) value during a period of at least 2 years and the proportion of patients developing PDR among cases with mild type PPDR, based on our previously proposed subclassification. Results: During follow-up, 27% of the total PPDR cases developed PDR. The mean HbA(1C) value in those patients who had developed PDR was 9.4% and was significantly higher than the 7.6% in those who had not developed PDR. The proportion developing PDR was 48% of the cases with a mean HbA(1C) value of 8.6% or more. By comparison, the proportion developing PDR was 8% among those with a mean HbA(1C) value below 8.6%. The proportion developing PDR was estimated to approximately double with each 1% increase in the mean HbA(1C) value. The cumulative occurrence rates of PDR at 2, 5, and 10 years were estimated to be 5%, 28%, and 60% in cases with a mean HbA(1C) value of 8.6% or more, and 0%, 7%, and 14% in those with a mean HbA(1C) value below 8.6%, respectively. Conclusion: Stricter systemic and ophthalmological control is indicated for cases with a mean HbA(1C) value exceeding 8.6%. Jpn J Ophthalmol 2001;45:523-527 (C) 2001 Japanese Ophthalmological Society.