This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
[{'content': 'Which of the following factor is related to diabetic retinopathy? \nSelect and explain. \nA. Duration of disease, B. Severity of disease, C. Family history, D. Control of diabetes', 'role': 'user'}, {'content': "Answer: A \nExplanation: Duration of DM and degree of glycemic control are the best predictors of the development of retinopathy; hypeension is also a risk factor. Nonproliferative retinopathy is found in many individuals who have had DM for >20 years (25% incidence with 5 years, and 80% incidence with 15 years of type 1 DM). Although there is genetic susceptibility for retinopathy, it confers less influence than either the duration of DM or the degree of glycemic control. Ref: Powers A.C. (2012). Chapter 344. Diabetes Mellitus. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.", 'role': 'assistant'}]