Aldo-keto reductase and sorbitol dehydrogenase enzymes in Egyptian diabetic patients with and without proliferative diabetic retinopathy.

BACKGROUND

Activation of the polyol pathway due to increased aldo-keto reductase (AKR) activity has been implicated in the development of diabetic complications, including proliferative diabetic retinopathy (PDR); however, the relationship between hyperglycaemia-induced activation of the polyol pathway in the retina and PDR is still uncertain.

METHODS

This study was conducted on 73 individuals, who were categorised into three groups: healthy individuals as normal control (15 age-matched subjects), diabetic patients treated with oral hypoglycaemic drugs (OHD, 34 patients), six of whom (17.7 per cent) were diagnosed with PDR and the rest were diagnosed with non-proliferative diabetic retinopathy (NPDR) and diabetic patients treated with insulin (INS, 24 patients), 12 of whom (50 per cent) were diagnosed with PDR and the rest had NPDR.

RESULTS

The AKR level in diabetic subjects showed a significant increase compared with the normal controls. Interestingly, AKR levels were significantly increased in the INS compared with the OHD group. Also the AKR level was significantly increased in the patients with proliferative compared with the non-proliferative retinopathy in both the insulin and oral diabetic groups. The sorbitol dehydrogenase (SDH) level in diabetic patients showed a significant decrease compared with the normal control level. Interestingly, the SDH level was significantly decreased in the INS compared with the OHD group. Also, the SDH level was significantly decreased in patients with proliferative compared with non-proliferative retinopathy in both INS and OHD groups. The HbA(1c) level in both INS and OHD subjects showed a significant increase compared with normal controls. In addition, the triglyceride level in insulin proliferative retinopathy showed a significant increase compared with other groups.

CONCLUSIONS

The AKR level was significantly increased in patients with proliferative compared with non-proliferative retinopathy in both insulin and oral diabetic groups. The SDH level was significantly decreased in patients with proliferative compared with non-proliferative retinopathy in both insulin and oral diabetic groups. Both AKR and SDH could be used as indicators for diabetic control.