New Delhi, June 10 -- You look fine. You feel fine. Your weight is normal, your energy is decent, and nobody at your last health check raised an eyebrow. Yet inside your body, a slow and damaging process may already be underway, one that carries no visible warning label and announces itself only when the damage is done. This is the reality of dysglycemia, or chronically dysregulated blood sugar, in people who appear outwardly healthy. It is not a rare case.

Researchers now estimate that hundreds of millions of people worldwide are living with prediabetes or early insulin resistance without knowing it. Many are slim. Many are young. Many are eating what they consider a reasonable diet.

"Standard blood sugar testing has a significant blin...