Assessing the changes in eye optics and visual functions in patients with insulin-dependent type 2 diabetes mellitus and their relationship with blood glucose level

Abstract

Purpose: To assess the changes in eye optics and visual functions depending on the level of blood sugar and glycated hemoglobin (HbA1c) in insulin-dependent type 2 diabetes mellitus (IPSD) patients with excessive body weight, who receive long-term insulin therapy.Material and methods. 32 patients (64 eyes), of which 84.4 % were women and 15.6 % men, with insulin-dependent diabetes mellitus (IPSD) but without severe general diabetic complications or concomitant eye pathology were monitored ophthalmologically for 3 years. The average duration of insulin therapy was 6 years. The average age of the patients was 60.94 ± 1.04 years; average weight, 89.1 ± 14.8 kg; average height, 163.8 ± 7.3 cm; average body mass index, 31.3 ± 4.8 kg/m2. The level of blood glucose level was determined daily with individual Accu-Check and/or OneTouch select glucometers, supplemented by scheduled monthly examinations with an endocrinologist. The level of glycated hemoglobin (HbA1c) was determined once every 3–6 months. Vision was measured by international requirements for patients with diabetes using the ETDRS (Early Treatment Diabetic Retinopathy Study Research Group) system with an ESV-3000 device. To assess lens transparency, the international Lens Opacities Classification System III (LOCS III) was used. Glycaemia level was monitored by the patients themselves with the help of individual blood glucose meters and by endocrinologists in scheduled monthly checkups. HbA1c level was measured once every 3 to 6 months.Results. Over the follow-up period, the subjective visual acuity slightly deteriorated. The anterior segment remained practically unchanged, the vitreous body showed a destruction increase, the state of the retina remained stable and conformed to that of nonproliferative diabetic retinopathy. The glucose level showed a significant drop, while the level of glycated hemoglobin HbA1c practically remained constant. The LOCS III criteria showed an increased clarity of the lens nucleus (NO), a worse transparency of cortical layers (C) deteriorated; the NC nucleus colour and P parameters of the posterior subcapsular layer practically remained the same. Conclusions. According to our data, during the development of diabetic cataracts in patients with type 2 IPSD, NO of the lens changes first followed by C changes (they become worse). With the normalization of glycemia level, diabetic retinopathy does not progress, the NO of the lens can improve, and the NC and P do not change. Normalization of glycemia is not a retarding factor for the already existing changes in C or the state of the vitreous. HbA1c is a marker and trigger for possible lens changes in patients with type 2 diabetes and prolonged insulin therapy. HbA1с is effective for tracking the dynamics of changes in the eye in these patients. The fact that the positive correlation of HbA1c and C at follow-up start changed to the negative correlation toward the end of the study indicates a disruption in lens state compensation and does not cancel the negative dynamics of state C even with a decrease in the level of HbA1c.