At what sugar level is insulin required?

Insulin is not needed in most of the cases of type 2 Diabetes Mellitus, if addressed properly to reduce the insulin resistance. There are some indications though like stressful situations like acute illness and surgeries, DKA (Diabetic Ketoacidosis) when the sugars are too high and insulin is low. Before starting a patient on insulin therapy, measuring Beta cell reserve using C-peptide level is a must irrespective of age. When functional insulin reserve is low (less than 10%), Insulin could be started. So the true indication of Insulin therapy in type 2 Diabetes Mellitus should not be guided by the sugar level but rather the Insulin reserve in the body.