India is becoming the diabetic capital of the world. The economic burden of diabetes and its complications are enormous. Fasting Blood Sugar (FBS) and Post Prandial Blood Sugar (PPBS) has always been the test of choice for diagnosis of diabetes though Oral Glucose tolerance test (OGTT) is considered often. But the trend of using HbA1c for diagnosis is not there in India although HbA1c is very often used for monitoring of diabetes. Many a time a clinician cannot rely on the laboratory reports for fasting sugar, resulting in under-diagnosis or over diagnosis of diabetes. After dealing with both the clinical and research aspect of diabetes for many years, we understand that diagnosis of diabetes and prevention of its complications among patient have always remained a challenge for Indian doctors. Though HbA1c have been advocated by several global associations for diagnosis of diabetes, it is not utilized in India. The book presents HbA1c in Indian scenario followed by a critical comparison between HbA1c, FBG and OGTT. It describes how and why HbA1c excels as a diagnostic test for diabetes among Indians, and how it can serve as a single biomarker for diagnosis and monitoring diabetes.