What blood sugar level requires insulin?
Insulin is usually recommended as the initial therapy for diabetes if a person's HbA1c level at diagnosis is greater than 10% or if someone's fasting blood glucose level is consistently above 250 mg/dl.
When should you take insulin?
When should I take insulin? If you take Regular insulin or a longer-acting insulin, you should generally take it 15 to 30 minutes before a meal. If you take insulin lispro (brand name: Humalog), which works very quickly, you should generally take it less than 15 minutes before you eat.