Basal vs. bolus insulin?

Understanding the difference between basal and bolus insulin is the foundation of intensive diabetes management. Basal insulin, often called "background" or long-acting insulin, is designed to keep your blood sugar stable when you are not eating, such as overnight or between meals. Your body constantly needs a tiny trickle of insulin to manage the glucose naturally released by your liver. Basal insulin (like Lantus, Tresiba, or Levemir) is injected once or twice a day and has no peak; it works slowly and evenly over 24 hours. Bolus insulin, on the other hand, is rapid-acting insulin (like Humalog, Novolog, or Fiasp) used for two specific purposes: to cover the carbohydrates in a meal you are about to eat, or to correct a high blood sugar reading. It begins working in 10 to 15 minutes, peaks around the one-hour mark, and is out of your system in about three to four hours. In a daily routine, the basal acts as your steady baseline foundation, while the bolus acts as the surgical strike to manage the massive influx of sugar from your food.