Rapid Reduction of HbA1c and Early Worsening of Diabetic Retinopathy: A Real-world Population-Based Study in Subjects With Type 2 Diabetes.

Objective: Early worsening of diabetic retinopathy (EWDR) due to the rapid decrease of blood glucose levels is a concern in diabetes treatment. The aim of the current study is to evaluate whether this is an important issue in subjects with type 2 diabetes with mild or moderate nonproliferative DR (NPDR), who represent the vast majority of subjects with DR attended in primary care.

Research design and methods: This is a retrospective nested case-control study of subjects with type 2 diabetes and previous mild or moderate NPDR. Using the SIDIAP ("Sistema d'informació pel Desenvolupament de la Recerca a Atenció Primària") database, we selected 1,150 individuals with EWDR and 1,150 matched control subjects (DR without EWDR). The main variable analyzed was the magnitude of the reduction of HbA1c in the previous 12 months. The reduction of HbA1c was categorized as rapid (>1.5% reduction in <12 months) or very rapid (>2% in <6 months).

Results: We did not find any significant difference in HbA1c reduction between case and control subjects (0.13 ± 1.21 vs. 0.21 ± 1.18; P = 0.12). HbA1c reduction did not show significant association with worsening of DR, neither in the unadjusted analyses nor in adjusted statistical models that included the main confounding variables: duration of diabetes, baseline HbA1c, presence of hypertension, and antidiabetic drugs. In addition, when stratification by baseline HbA1c was performed, we did not find that those patients with higher levels of HbA1c presented a higher risk to EWDR.

Conclusions: Our results suggest that the rapid reduction of HbA1c is not associated with progression of mild or moderate NPDR.