There are different types of insulin available to treat diabetes. Short-acting insulin is a common one that peaks 2 to 6 hours after injection. On the other hand, long-acting insulin lasts in the body for up to 24 hours. There is another kind of diabetes medication called mealtime or bolus insulin. Mealtime insulin is designed to affect blood sugar levels during a meal quickly. It starts working just 15 minutes after injection. Bolus insulin lasts up to 3 hours in the body. Mealtime insulin has its benefits. It closely mimics natural insulin released by your body. It also allows mealtimes to be more flexible.