Forgotten premeal injection (multiple injection treatment)
Take the same dose of insulin or decrease it by a unit or two, if you remember immediately after you have eaten. If 1 or 2 hours have passed, you can try taking about half the dose. If a longer time has passed, add a few units to your next meal injection, but not until you have measured your blood glucose level.
Forgotten bedtime injection (multiple injection treatment)
If you wake up before 2 AM you can still take your bedtime insulin, but you should decrease the dose by 25-30% or 1-2 units for every hour that has passed since the normal time of injection. If there are less than 5 hours before your usual waking time, measure your blood glucose and take an injection of regular short-acting insulin if you have this. You can try a dose with one third or a quarter of the number of units of your normal bedtime injection of intermediate-acting insulin. However, never inject more than 0.1 U/kg (0.5 U/10 lb) of body weight at one time.
If you have forgotten your evening or bedtime dose you can take it when you remember it, as long as only a few hours have passed. You may need a small dose of rapid-acting insulin if your blood glucose has already risen. If you remember in the morning, try taking approximately half of the dose you should have taken in the evening. If you wake up with high blood sugar, nausea and elevated levels of ketones in your blood or urine, you have symptoms of insulin deficiency. Take 0.1 U/kg (0.5 U/10 lb) body weight of insulin and measure your blood glucose again after 1-2 hours. If your glucose level has not decreased after 2 hours, take another dose of 0.1 U/kg (0.5 U/10 lb) body weight. If you still are feeling sick or if you vomit, you should contact your doctor immediately.
Forgotten injection with twice-daily treatment
If, for example, you forget the morning dose, take the same dose or decrease the regular short-acting (or rapid- acting) part by 1 or 2 units if you remember immediately after having eaten. If you remember after an hour or two, you can try decreasing the rapid- or short-acting part by about half and the intermediate part by about 25%. If you remember your injection even later, measure your blood glucose before the next meal and take only rapid- or short-acting insulin at this meal. If you are using pre-mixed insulin, it won't be possible to decrease only one of the components. Give a smaller dose of this insulin when you remember, or use only rapid or short-acting insulin until it is time for the afternoon injection.
If you have forgotten your evening injection and remembered at night, you must take a smaller dose of intermediate acting insulin before going to bed. A little more than half should be enough but you must test this with blood glucose controls. You will probably also need an injection of rapid- or short-acting insulin at your evening snack. Try the same dose (or a few units less) than the rapid- or short-acting part of your evening injection. You should check your blood glucose at night to avoid hypoglycaemia.