What to do after hypoglycemia

The brain takes longer to recover than blood glucose does. During the hypoglycemic episode, the brain ran on less fuel. The sympathetic nervous system was strongly activated, and so was the release of adrenaline from the adrenal glands. Both leave traces for a few hours.

The effect has been measured experimentally. Reaction time remains impaired for another 40–75 minutes after blood glucose returns to normal [1]. How long recovery takes varies greatly from one patient to another. The usual symptoms are headache, tiredness, difficulty concentrating and a feeling of exhaustion [2]. They do not necessarily mean you are still hypoglycemic, and they are not automatically treated with yet another dose of carbohydrates. Check your blood glucose, then give yourself time to recover.

Yes, it happens often. About a third of hypoglycemic episodes are followed within two hours by blood glucose above 180 mg/dL (10.0 mmol/L) [3]. Most often, you either ate more than you needed or did not wait the 15 minutes before taking something else [4]. The sensor, which lags behind, reinforces the false impression that nothing has happened [5].

The consequence is not just high blood glucose. It is often followed by an insulin correction and then a new hypoglycemic episode, so the day turns into a seesaw [3]. The right amount of carbohydrates and the patience to wait the 15 minutes solve the problem better than any later adjustment [4].

You make no correction in the first few hours. You wait, check your blood glucose and let the insulin already in your body do its work. High blood glucose for a few hours, as an isolated event, does no long-term damage.

The usual mistake is an immediate insulin correction on top of insulin that is still active. The result is a second hypoglycemic episode, which can be deeper and harder to feel than the first [6]. Write the episode down, so that next time you use a better-suited amount of carbohydrates.

It depends on how much of the insulin effect is left and on when your next meal is. If rapid-acting insulin is still active or the next meal is a long way off, a snack with slowly absorbed carbohydrates helps prevent a second episode [7]. Always keep in mind the risk posed by insulin that is still active.

If your meal is coming soon, the snack is not needed, because it often leads to higher blood glucose later. The rule is not universal, as it depends on the timing. Moreover, a snack taken routinely after every hypoglycemic episode leads to weight gain over time, without solving the cause.

You write down four things: the time, the measured value, what you did beforehand and how you corrected it. Add a short note about your meal, your physical activity and the insulin you took in the previous hours [8].

These notes are worth far more than your memory. At your next checkup, your doctor needs patterns, not a general impression. Many apps and modern insulin pumps record part of the data automatically, but only you can add the context [9].

You look for the mismatch between insulin and your needs at that moment [8]. The useful questions are few:

• The insulin dose — whether you took more than usual.
• The meal — whether you ate less.
• Physical activity — whether you moved more than usual.
• Alcohol — whether you had alcoholic drinks.
• The injection site — whether you injected the dose in a different place.

Also consider when the hypoglycemia occurred. Hypoglycemia two hours after a meal usually points to a mealtime dose that was too high. One that occurs at night or before meals is more strongly linked to a basal insulin dose that is too high. This difference guides the whole adjustment that follows [8].

Immediately after any severe episode, especially if it required glucagon. You also notify the team after any episode below 54 mg/dL (3.0 mmol/L) or if an episode occurred for no apparent reason.

In these situations, do not wait for your next appointment. A single level 2 or level 3 episode is enough to warrant a review of the treatment plan [4]. This calls for a change in the treatment plan, structured education and additional use of technology [4] [10]. An adjustment made in time prevents hypoglycemic episodes from recurring.

There is no number that applies to everyone, but there is a measure. For most adults, the time spent below 70 mg/dL (3.9 mmol/L) should not exceed 4% of the day, which is about one hour. Below 54 mg/dL (3.0 mmol/L), the limit is 1%, which is about a quarter of an hour [11].

In practice, daily mild episodes or two nighttime episodes a week are a clear signal that your treatment needs adjusting. A single severe hypoglycemic episode or one below 54 mg/dL (3.0 mmol/L) is enough to warrant a review of your treatment [4]. Remember that the number matters less than the pattern in which the hypoglycemic episodes occur.

Not right away. The high blood glucose that follows the treatment of hypoglycemia usually comes down on its own, as the insulin taken earlier keeps working. A correction added now overlaps with the active insulin already there.

If your blood glucose stays high after a few hours and the rapid-acting insulin has clearly finished working, a correction becomes reasonable. Always check your active insulin. Remember that the value shown by your pump or an app depends on the duration of insulin action set in the device. A duration set too short shows less active insulin than there really is [12]. Stacking corrections is one of the common causes of hypoglycemia with no apparent explanation [12].

Not right away. Wait until your blood glucose rises above 70 mg/dL (3.9 mmol/L) and, in addition, until you feel completely normal. Attention and reaction time recover more slowly than blood glucose [1].

For risky activities, such as driving, swimming or working at heights, wait at least 45 minutes after your measured glucose has returned to normal [1] [13]. Do not start driving with your glucose below 90 mg/dL (5.0 mmol/L), because it can change a lot in the first 20 minutes of driving [14]. For everyday activities, it is enough to feel well and have a stable reading. If physical exercise is coming up, postpone it or reduce its intensity.