Missing an insulin dose is common in diabetes management, but it can lead to rapid changes in blood sugar levels. When this happens, remain calm and avoid the impulse to immediately double your next dose. Insulin therapy is highly individualized, so you should always have a specific action plan created with your healthcare provider for these situations. If you are unsure about the correct course of action, contacting your doctor or a diabetes specialist is the safest choice to maintain control and prevent complications.
Assessing the Situation and Insulin Type
The immediate action you take depends on two factors: the type of insulin missed and the time passed since the dose was due. Insulin falls into two main categories: basal and bolus. Basal insulin, often long-acting, provides a constant background level to regulate blood sugar between meals and overnight. Bolus insulin, which is rapid or short-acting, is used to cover carbohydrate intake from meals or to correct high blood sugar readings.
Knowing which type was missed is fundamental because the timing window for safely taking a late dose varies significantly. Missing a basal dose affects overall blood sugar control for a full day. Missing a bolus dose results in a sharp, temporary blood sugar spike after a meal. The distinct action profiles of these insulins necessitate different protocols to safely get your regimen back on track.
Protocol for Missed Basal Insulin
Basal insulin (e.g., glargine or degludec) provides coverage for approximately 24 hours to maintain stable blood glucose. If you miss a once-daily basal dose and realize it within 3 to 4 hours of the scheduled time, take the full, usual dose immediately. Taking the dose late within this short timeframe should not significantly disrupt your schedule. However, monitor blood sugar more closely afterward to check for unexpected lows.
If more than 4 hours have passed, or if you are close to the time of your next scheduled dose, the recommendation changes to prevent insulin stacking. In this scenario, administer half of your normal basal dose right away for background coverage. Return to your regular, full dose at the usual time the next day. This helps re-establish your normal schedule without risking a dangerous overlap. If you are on a split-dose basal regimen, monitor your glucose closely until the next scheduled injection, using small correction doses of rapid-acting insulin if blood sugar rises significantly.
Protocol for Missed Bolus Insulin
Bolus insulin (e.g., Humalog, Novolog) is taken to match meal carbohydrates, and its effect lasts about 3 to 6 hours. If you realize you missed your mealtime bolus immediately after finishing your food, you can still take the full dose. Be aware that the insulin’s peak action will happen later than the meal’s digestion. This delayed timing can cause a post-meal blood sugar spike followed by an increased risk of hypoglycemia several hours later.
If it has been more than one or two hours since your meal, taking the full original meal dose is not advised due to the hypoglycemia risk before your next meal. Instead, check your current blood sugar level and only administer a correction dose to bring a high reading back into your target range. A correction dose is calculated based on your personal insulin sensitivity factor and only covers the current high blood sugar, not the carbohydrates from the missed meal. If your blood sugar is high, give the correction dose immediately. If you are about to eat again, combine this correction with the insulin needed for the new meal.
Recognizing and Responding to Hyperglycemia
A missed insulin dose, especially basal insulin, often leads to hyperglycemia (high blood sugar). Common symptoms include increased thirst, frequent urination, fatigue, and blurry vision. Never attempt to correct a high reading by arbitrarily doubling your next scheduled dose, as this significantly raises the risk of severe hypoglycemia.
Monitor your blood sugar frequently, such as every two to four hours, after realizing a dose was missed. A severe, life-threatening complication of prolonged hyperglycemia is Diabetic Ketoacidosis (DKA), most common in Type 1 diabetes. Signs of DKA include nausea, vomiting, abdominal pain, a fruity odor on the breath, and deep, rapid breathing. If your blood sugar is consistently high (over 250 mg/dL) or if you experience DKA symptoms, check for ketones using a blood or urine test. Elevated ketones and DKA symptoms require immediate medical attention; contact your healthcare provider or seek emergency care.
Strategies to Prevent Future Missed Doses
Developing a consistent routine is the most effective way to prevent missed insulin doses. Link your injection to a non-negotiable daily habit, such as immediately after brushing your teeth or before your daily coffee. Integrating the injection into a reliable part of your day helps turn it into an automatic behavior.
Technology can serve as a helpful safeguard against forgetfulness. Utilize reminder applications on your smartphone, set recurring alarms, or use a connected insulin pen that logs the time and amount of your last dose. Keeping your insulin supplies in a designated, visible spot, or asking a family member or caregiver for a gentle reminder, also creates effective barriers against future missed injections.