INS and prediabetes syndrome: There has been an interest in studying the impact of vitamin D supplementation on glycaemic indices in subjects with prediabetes and hypovitaminosis D. Oral glucose tolerance test (OGTT) based insulin sensitivity test, i.e., oral glucose insulin sensitivity (OGIS) index at 120 minutes, is a simple surrogate marker related to pathophysiology of diabetes that can be used for research studies in large subjects [5].