The optimal glycated hemoglobin (HbA1c) target in people with type 2 diabetes mellitus (T2D) remains an area of ongoing clinical debate, particularly in those with existing microvascular disease. A randomized controlled trial published in Clinical Diabetology compared the effects of a tighter HbA1c target (< 7.0%) versus a less intensive target (< 7.5%) on microvascular outcomes in adults with poorly controlled T2D and non-proliferative diabetic retinopathy.
In this parallel-group trial, 80 adults aged 18–60 years with T2D, baseline HbA1c > 7.5%, and mild-to-moderate non-proliferative diabetic retinopathy were randomized to a tighter target (n = 33) or a less tight target (n = 47) and followed for 6 months. Glycaemic indices, renal parameters including albumin-to-creatinine ratio and estimated glomerular filtration rate, and neuropathy assessed using the Douleur Neuropathique 4 questionnaire were evaluated at baseline and follow-up. Retinopathy progression was defined as a ≥ 1-step increase on the Early Treatment Diabetic Retinopathy Study severity scale.
At 6 months, the tighter target group achieved lower HbA1c compared with the less intensive group (6.23% ± 0.35 vs. 7.27% ± 0.23; p < 0.001), along with lower fasting and postprandial glucose levels (both p < 0.001). However, retinopathy worsening was more frequent in the tighter target group (63.6% vs. 14.9%; p < 0.001). The overall rate of new or progressive microvascular complications was also higher in this group (84.8% vs. 31.9%; p < 0.001), including greater occurrence of albuminuria (36.4% vs. 14.9%; p = 0.026) and neuropathy (39.4% vs. 10.6%; p = 0.002).
These findings indicate that while tighter HbA1c targets were associated with improved glycaemic measures, they were also linked to higher rates of short-term retinopathy worsening and microvascular complications over 6 months. The relatively small sample size and short follow-up period should be considered when interpreting the results. The findings highlight the importance of individualized HbA1c targets and careful monitoring of microvascular outcomes in this population.
