We read with great interest the article by Molitch et al. (1), concerning the association between high levels of HDL cholesterol and albuminuria in type 1 diabetes. We have found similar results in a group of 157 patients with long-standing type 1 diabetes but in relation to retinopathy, which seems to be a more objective marker of microangiopathy than albuminuria in diabetes. Retinopathy was assessed by two experienced ophthalmologists using direct ophthalmoscopy on dilated pupils, followed, if necessary, by fluorescein angiography. Pictures of the eye fundus were collected. We divided our patients into two groups, one with (n = 118) and one without (n = 39) retinopathy. Two assessed groups were identical with respect to age (42.3 ± 12.6 vs. 39.9 ± 12.5 years, P > 0.05) and duration of diabetes (26.5 ± 6.9 vs. 25.7 ± 6.5 years, P > 0.05). Similarly to Molitch et al. (1), HDL cholesterol levels were significantly lower in patients with diabetic retinopathy than in those that did not have any changes at fundus of the eye (1.49 ± 0.4 vs. 1.65 ± 0.42 mmol/l, P = 0.039). Higher levels of HDL cholesterol (≥1.6 vs. <1.6 mmol/l) were associated with a five-times–lower likelihood of diabetic retinopathy (OR 0.20 [95% CI 0.06–0.70], P = 0.01). Of patients with retinopathy, 55% had positive microalbuminuria. However, the majority of patients with retinopathy were treated with ACE inhibitors, which must have influenced this percentage.
Contrary to Molitch et al. (1), we have not found any differences in HbA1c between patients with and without retinopathy (8.2 ± 1.4 vs. 8.1 ± 1.3%, P > 0.5). Our study suggests that high HDL cholesterol may, independently of glycemic control, prevent the development of microvascular complications in type 1 diabetes. These results could be related to antioxidant, antithrombotic, and anti-inflammatory properties of HDL particles (2). Interestingly, structural modifications of HDL mediated by various mechanisms, including glycation, oxidation, and enzymatic degradation, may affect their functional and atheroprotective properties (3). This may suggest that not only quantity but also quality of HDL particles play a role in the damage of endothelium.
Molitch et al. (1) and our studies confirm the hypothesis that the higher the levels of HDL cholesterol, the lower the risk of late diabetes complications.
