When the blood sugar drops too low, the body reacts, trying to return the blood sugar level back to normal. Many of the body’s glands activate and release hormones into the blood, which try to raise the blood sugar level in different ways, primarily by releasing sugar stored in the liver. Of these antagonistic hormones, the most important ones are glucagon, which is released by the pancreatic islets, as well as adrenalin and cortisol, which are released by the adrenal gland.
The symptoms resulting from adrenalin begin first. The neurological symptoms do not normally start until the blood sugar level has dropped a little bit more. During sleep, the symptoms of hypoglycaemia include restlessness, sweating and nightmares. If your blood sugar was low during the night, it may manifest as a fluctuating morning blood sugar.
Most commonly, the symptoms of low blood sugar occur when blood sugar drops below the hypoglycemic threshold of 4 mmol/l. However, these sensations are individual and influenced by various factors. For instance, the general balance of blood sugar management and the rate at which blood sugar decreases affect the symptoms of low blood sugar. If blood sugar level has been consistently high for a long time, even a blood sugar level of 4–5 mmol/l can trigger symptoms of low blood sugar. On the other hand, if blood sugar level is generally low, the symptoms of low blood sugar may be weakened or disappear entirely.
The symptoms of low blood sugar can also change over the years. The initial feelings related to adrenaline (i.e. insulin sensations) may diminish, and neurological symptoms that typically emerge more slowly may be the first sign of low blood sugar.