Repeated sugar crashes can switch off the body's own alarm
Most people feel low blood sugar around 55 mg/dL: sweating, a racing heart, sudden hunger. Yet people with diabetes who suffer frequent lows can lose those warning signs entirely, a state called hypoglycemic unawareness that affects an estimated 20 to 40 percent of type 1 diabetics and leaves them far more exposed to severe episodes.
Hypoglycemia is blood glucose below the normal floor, usually taken as 70 mg/dL, or 3.9 mmol/L. The body normally holds glucose between about 70 and 110 mg/dL through a web of controls involving insulin and glucagon, which is why true lows are rare in people without diabetes. A single low reading is not enough to diagnose it. Clinicians use Whipple's triad: typical symptoms, a measured low level, and relief once glucose is restored.
Symptoms fall into two families. Adrenergic ones come from the body's alarm response: a fast pulse, sweating, nervousness and hunger. Neuroglycopenic ones reflect a brain starved of fuel: tiredness, confusion, slurred speech, seizures and, at worst, unconsciousness or death. They tend to arrive quickly. With repeated episodes the threshold that triggers symptoms drifts lower, the adrenergic signals fade, and a person may only notice trouble when levels are dangerously low.
Diabetes medicines are the commonest cause, especially insulin and sulfonylureas taken in too large or badly timed doses, such as insulin before a meal that is then skipped. Fasting, unusual exercise and alcohol, which blocks the liver's glucose output, add to the risk. Serious illness can also drive sugar down. In sepsis the body burns glucose fast while stressed organs make less; liver failure cuts production at its main source; and failing kidneys clear insulin slowly so it lingers. Newborns in their first 48 hours adjust hormone levels and can dip temporarily.
A rarer cause is deliberate insulin use by someone without diabetes, sometimes for weight loss or as part of a factitious disorder; blood tests showing high insulin but low C-peptide give it away. Standard treatment, according to the literature, is 10 to 20 grams of fast carbohydrate such as glucose tablets or juice for a conscious person, or glucagon when swallowing is impossible, while cases unrelated to diabetes call for treating the underlying disease.
Source: Hypoglycemia
