Natural History of Retinopathy in FCPD, MODY and IDDM - A Follow-Up Study

This paper reports for the first time on the natural history of diabetic retinopathy in three forms of youth onset diabetes seen in our country based on a 4 year follow-up study. Forty patients each with Fibrocalculous Pancreatic Diabetes (FCPD), Maturity Onset Diabetes of Youth (MODY) and Insulin-Dependent Diabetes Mellitus (IDDM) were followed for periods up to four years with annual fundus colour photography using an international retinal grading system. All patients had early background diabetic retinopathy at the onset of the study. The rate of progression of retinopathy was found to be similar in all three study groups. The study proves that patients with secondary forms, of diabetes (FCPD) also develop retinopathy at the same rate as primary forms of diabetes. Moreover, it disproves earlier studies that patients with MODY are protected from retinopathy. Diabetic retinopathy is the leading cause of blindness in all developed countries [1]. There is very little data on diabetic retinopathy from developing countries. In South India, there are some unique forms of diabetes that are extremely rare in Western countries. Fibrocalculous Pancreatic Diabetes (FCPD) is a type of diabetes that is secondary to Tropical Calcific Pancreatitis (TCP) [2]. The highest known prevalence of FCPD in the world is in Southern India [3]. Maturity Onset Diabetes of Youth (MODY) is a form of Non-Insulin-Dependent Diabetes Mellitus characterized by autosomal dominant inheritance and onset in youth. We [4] and others [5] have shown that MODY is highly prevalent among Indians. It was earlier believed that retinopathy was rare in FCPD [2] and in MODY subjects [6]. We have documented in earlier studies that retinopathy does occur in FCPD [7] and in MODY patients [4]. However both these studies were cross-sectional in nature and there is virtually no longitudinal studies on the natural history of diabetic retinopathy in our country. In this study we present a four year follow-up study of diabetic retinopathy in FCPD and MODY patients and compare the results with a group of Insulin-Dependent Diabetes Mellitus (IDDM) patients. Our aim was to study patients of similar age group, namely FCPD, MODY and IDDM, all of which present at a younger age. For this reason, classical NIDDM which usually develops at a later age, was not included in this study. PATIENTS AND METHODS The criteria for diagnosis of diabetes was based on WHO Study Group criteria [8]. The criteria for diagnosis of FCPD, MODY and IDDM are given below: