Glycosylated Hb (GHb) will be proportional to mean plasma glucose level during previous 6-12 weeks. It help determine whether you are at an increased risk of developing diabetes; to help diagnose diabetes and prediabetes; Advantages to using HbA1c for diagnosis include: Provides an assessment of chronic hyperglycemia,No fasting is necessary,A single test could be used for both diagnosing and monitoring diabetes