Increased retinopathy occurrence in type 1 diabetes patients with increased serum levels of the advanced glycation endproduct hydroimidazolone.

PURPOSE: We aimed to investigate associations between serum levels of the advanced glycation endproduct methylglyoxal-derived hydroimidazolone (MG-H1) and retinopathy in a sample of patients with type 1 diabetes. METHODS: We conducted a cross-sectional study in a Scandinavian ophthalmology outpatient clinic on 61 randomly selected patients with type 1 diabetes. Blood samples and retinal photographs were taken at the same visit. Serum levels of hydroimidazolone immunoreactivity were determined using an immunoassay, and levels of retinopathy were determined from seven standard field stereo photographs of each eye according to the ETDRS method. Results were compared between patients with and without retinopathy. RESULTS: Hydroimidazolone quartiles were significantly associated with retinopathy (p = 0.013). The most profound increase in occurrence of retinopathy was observed from the lowest to the second-lowest hydroimidazolone quartile. Adjusted for duration of diabetes using logistic regression, a significant difference in the presence of retinopathy was found when comparing the lowest quartile with the rest (p = 0.022). CONCLUSIONS: In our patients with type 1 diabetes, serum levels of hydroimidazolone were found to be associated with retinopathy. This is in keeping with findings in a larger sample of patients with type 2 diabetes.

Increased vitreous levels of hydroimidazolone in type 2 diabetes patients are associated with retinopathy: a case-control study.

PURPOSE: As advanced glycation endproducts (AGEs) and the vitreous body are both considered to be involved in the development of diabetic retinopathy and hydroimidazolone is one of the most prominent AGEs, we compared vitreous and serum hydroimidazolone in diabetes patients with proliferative diabetic retinopathy (PDR) to levels in non-diabetes controls, co-measuring vitreous albumin and vascular endothelial growth factor (VEGF). METHODS: In a cross-sectional case-control study design, we used immunoassays to compare vitreous and serum hydroimidazolone and VEGF levels in 23 consecutive type 2 diabetes mellitus patients with a median known diabetes duration of 12 years (range 1-38 years) with those in 32 non-diabetes age-matched controls undergoing vitrectomy. RESULTS: Vitreous hydroimidazolone was increased in the PDR group (median 1.3 U/ml, range 0.5-3.3 U/ml) compared with controls (median 0.8 U/ml, 0.5-2.5 U/ml) (p = 0.026). Hydroimidazolone levels in serum and vitreous correlated (r = 0.49, p = 0.019). In PDR, vitreous VEGF levels were increased (median 1600 pg/ml, range 20-14 700 pg/ml) compared with controls (median 7 pg/ml, range 2-500 pg/ml) (p < 0.001). Similarly, vitreous albumin concentration was increased in PDR (median 1.6 g/l, range 0.7-3.0 g/l) compared with controls (median 0.3 g/l, range 0.08-1.9 g/l) (p < 0.001). Albumin could not explain the differences in vitreous VEGF levels in a logistic regression analysis. No correlation was found between vitreous levels of VEGF and hydroimidazolone (r = 0.12, p = 0.59). CONCLUSIONS: Increased vitreous hydroimidazolone is associated with diabetic retinopathy, possibly due to a blood-retinal barrier breakdown. Irrespective of origin, it may add to the ocular damage and needs further causal investigation. Increased VEGF in diabetic vitreous is probably of intraocular origin. It is not associated with vitreous hydroimidazolone.