The 5.7% threshold is convenient, not biological.
Where risk actually starts
Indian metabolic data shows insulin-resistance signals appearing at HbA1c values as low as 5.4. By 5.6 the trajectory is set; by 5.7 it's a label.
What we measure alongside
Fasting insulin, HOMA-IR, triglyceride/HDL, ApoB. Together they tell the story HbA1c alone cannot.