Study of the Relationship between Diabetic Retinopathy, Basal Insulin Therapy (Glargine or NPH) and Insulin-Like Growth Factor 1 Serum Level

Abstract

Abstract Background Diabetic retinopathy (DR) is the major cause of preventable blindness worldwide. DR is a microvascular complication of diabetes mellitus that is more prevalent in patients with type 1 diabetes. Type 1 diabetes mellitus is an autoimmune disease that leads to insulin deficiency so patients require long term therapy with basal insulin for optimum glycemic control. Insulin- like growth factor 1 (IGF-1) is an important growth factor that is involved in cell proliferation and angiogenesis. There is a lot of evidence that IGF-1 is tightly related to DR development. Insulin Glargine is a long-acting insulin analogue which is peak-free and less hypoglycemic as compared to the intermediate-acting NPH insulin. Glargine has an increased affinity to IGF-1 receptor and this raised concern about its role in development of DR. The relationship between diabetic retinopathy, basal insulin therapy and IGF-1 serum level is still in debate. Aim we aimed to compare the incidence and severity of diabetic retinopathy in type 1 diabetic patients on basal insulin therapy (Glargine or NPH) and its relation to serum IGF-1 level. Methods The current study included 88 subjects with type 1 diabetes divided into 44 on basal insulin therapy with Glargine and actrapid ( Group A) and 44 on NPH and actrapid ( Group B). Hemoglobin A1c, Total cholesterol, Triglycerides, High density lipoproteins, Low density lipoproteins and serum IGF-1 levels were assessed. Full clinical examination including (weight, height, BMI), vital signs (pulse, blood pressure) was done and Fundus examination by Optomed Aurora® IQ handheld fundus camera. Results On comparing the 2 studied groups, There was no statistical significant difference as regarding fundus examination findings between studied groups (P value = 0.429). There was no statistically significant relation between diabetic retinopathy and serum IGF-1 (P value = .080 with Mean ± SD of serum IGF-1 level in patients with Normal fundus 14.8 ± 11 vs. Patients with Diabetic retinopathy 21.3 ± 16.9). There was statistically significant association between diabetic retinopathy and duration of diabetes (P value< 0.05 with Mean ± SD of diabetes duration in patients with Diabetic retinopathy 17.7 ± 6.9 vs. Patients with Normal fundus 14.6 ± 5.6). There was a statistical significant difference as regarding age (P value< 0.05 with Mean ± SD of age in Group B regimen 28.4 ± 6.7 vs. Group A 25.5 ± 4.9). Conclusion Serum IGF-1 levels showed no statistically significant difference in patients either on Glargine or NPH and also in patients either with normal fundus or with diabetic retinopathy. The incidence and severity of diabetic retinopathy in patients with type 1 diabetes mellitus is directly proportionate to duration of disease. No noted difference concerning diabetic retinopathy changes between patients on basal insulin therapy either Glargine or NPH.