Impaired awareness of hypoglycemia

It means that you no longer feel hypoglycemia when it occurs, or that you feel it very late. The sympathetic nerves no longer sound the alarm at the usual blood glucose values. As a result, trembling, sweating and palpitations are missing. Sometimes the first sign is confusion itself or a mistake in your reasoning [1]. How long you have had diabetes matters a great deal, but it is not the main cause of this phenomenon. The problem actually lies with the hypoglycemic episodes of recent days and weeks [2].

Each hypoglycemic episode weakens the response of the autonomic nervous system to the next one [3]. It is not a personal weakness and it does not mean carelessness, but an adaptation of the body. Fortunately, this unhelpful adaptation can be largely reversed. The medical term is hypoglycemia-associated autonomic failure, abbreviated HAAF. It is different from classic autonomic neuropathy, a complication of long-standing diabetes that is not reversible [4]. The distinction matters, because it decides whether the situation can be changed or not.

The alarm threshold shifts. After each hypoglycemic episode, the blood glucose level at which the sympathetic nervous system is activated drops a little further [5]. After several episodes, this threshold can fall below the level at which the brain already starts to have trouble functioning [6].

The result is a dangerous reversal in the order of symptoms. Normally, the warning signs appear before the ones that come from the brain and give you time to act. With hypoglycemia unawareness, confusion is what comes first, which is exactly what you did not need in order to treat the hypoglycemia. It is a vicious circle, in which hypoglycemia causes its own unawareness, and unawareness increases the risk of hypoglycemia [3].

You can tell by a few clear clues [7]:

• Low values without symptoms — you find low values on your sensor without having felt anything.
• What others notice — people around you tell you that you acted strangely, and you do not remember it.
• Needing help — you had a hypoglycemic episode in which you needed someone else's help.

Another sign is a change in the threshold at which you feel something. If you used to feel hypoglycemia at 65 mg/dL (3.6 mmol/L) and now feel the first signs only at 50 mg/dL (2.8 mmol/L), your warning threshold has shifted. When you see your doctor, remember that your sensor reports show this better than your memory does [8].

The question used in practice is whether you always notice when a hypoglycemic episode begins. A negative answer calls for a more detailed assessment [1]. There are also longer questionnaires, such as Clarke and HypoA-Q, which assess several aspects of the problem [9].

It is worth answering honestly, even if you do not like the answer. Hypoglycemia awareness is assessed in every patient treated with insulin, at least once a year [1]. Its purpose is to change the treatment plan. Hiding the problem only increases the risk of a severe episode.

Yes, considerably. Patients with impaired awareness of hypoglycemia have about six times more severe episodes per year than those with normal awareness [10]. The explanation is simple. Without a warning there is no chance of a timely correction with carbohydrates, and blood glucose keeps falling.

For this reason, hypoglycemia unawareness is listed among the major risk factors for severe hypoglycemia. Its presence alone is enough to place a patient at high risk [1]. The practical consequence is a short-term change in glucose targets and closer monitoring, especially with the help of technology [1] [11].

Yes, in many patients. It is one of the few problems in diabetes that can often be fully resolved [2]. The method is strict avoidance of hypoglycemia, which allows the alarm threshold to rise back to normal [6] [12]. Sensors reduce the number of hypoglycemic episodes, but in clinical trials they have not also reduced the frequency of impaired awareness of hypoglycemia [13].

Avoidance has to be as complete as possible, including mild episodes and those that occur at night. A single episode every few days may be enough to keep the warning threshold too low [4]. That is why the plan is made with your doctor and relies on a glucose sensor, with alarms set somewhat higher than usual.

Usually two to four weeks. Symptom perception can return fully to normal within 3–4 weeks, with a visible improvement after only three days [14]. The hormonal part does not recover as quickly. The glucagon response remains low, while the adrenaline response recovers only partially at best, and only after a few months [6] [14].

In other words, you can regain the warning given by the autonomic nervous system, that is, your reaction time, but not the body's automatic hormonal defense. The result usually lasts only as long as you keep strictly avoiding hypoglycemia. If hypoglycemic episodes return, the threshold usually drops again within just a few days [4].

Temporarily relaxed targets, set by your doctor. In practice, this means accepting somewhat higher values for a few weeks, with the sensor alarm moved higher [1]. The aim is to stop reaching the hypoglycemia threshold at all.

It is a short-term measure, not giving up on strict glucose targets. Glycated hemoglobin (HbA1c) may rise slightly during this period, which is considered acceptable in exchange for regaining the hypoglycemia warning [12]. When the signs of hypoglycemia return, the glucose targets gradually become stricter again.

Partly, but it is the best solution available. The sensor alarm warns you whether or not you feel anything, so it takes over the lost warning function [15] [16]. The predictive alarm, which alerts you before the threshold is reached, is the most useful in this situation. The effect was measured in patients with impaired awareness of hypoglycemia or a severe episode in the previous year, treated with multiple daily injections. In them, a sensor with alarms reduced the number of hypoglycemic episodes by about 72% [11].

However, the sensor does not restore the body's hormonal response, and it does not help if the alarms are turned off or ignored. A patient who no longer feels hypoglycemia needs a glucose sensor worn continuously and alarms that stay on, especially at night [7]. Systems that automatically suspend insulin delivery based on sensor data add an extra level of safety [17].

Your doctor, at your routine checkup. Hypoglycemia awareness should be checked at least once a year in all patients at risk of hypoglycemia. The check is repeated whenever a situation suggests the problem [1].

The assessment starts with questions about recent episodes and with your sensor reports. If the result confirms that the warning has been lost, a structured plan to solve the problem follows. In this case, referral to a specialist experienced in this area is recommended [1]. Structured education is part of the treatment, just like setting insulin doses [18].