High Blood Sugar Damages You Over Decades. Low Blood Sugar Can Do It Before Lunch

It happens for two reasons. Repeated lows blunt the body's counter-regulatory response, so each episode makes the next one less noticeable, which is a genuinely vicious cycle. And autonomic neuropathy can damage the nerve pathways that generate the adrenaline response in the first place.

Someone with hypo unawareness may go from apparently fine to needing assistance with no intervening stage. They should not be driving without checking, and they are the group for whom continuous glucose monitoring with alarms is not a convenience but a safety device, since the alarm replaces the warning system the body has lost.

The condition is partially reversible. Scrupulously avoiding lows for several weeks can restore some awareness, which usually means deliberately accepting slightly higher running glucose for a period. That is a legitimate clinical decision and not a failure.

How should a hypo be treated?

The widely taught approach is the rule of 15, and its value is that it stops the most common mistake.

Take around 15 grams of fast-acting carbohydrate: glucose tablets, a small glass of juice or regular soft drink, or honey. Wait 15 minutes. Re-test. If still low, repeat. Once glucose has recovered, eat something longer-lasting if the next meal is not imminent.

The mistake the rule prevents is over-treating. A frightened person low on glucose has an overwhelming urge to eat everything within reach, and the result is a rebound high a couple of hours later, which prompts a correction dose, which can produce another low. That cycle is exhausting and it is how people spend a whole day chasing their own tail.

Note also that chocolate is a poor rescue food despite being the intuitive one. Fat slows gastric emptying, which is exactly the wrong property when you need glucose in your blood within minutes.

For level 3, when the person cannot swallow safely or is unconscious, the answer is glucagon, now available as a nasal powder and in pre-filled injectors that a family member can use without training. Nothing should be put in the mouth of an unconscious person. Anyone using insulin should have glucagon available and, more importantly, somebody nearby who knows where it is.

What causes lows in the first place?

Usually a mismatch, and usually one of five things: too much insulin or sulfonylurea, a missed or delayed meal, more activity than usual, alcohol, or improving kidney function changing how drugs are cleared.

Alcohol deserves specific mention because the mechanism surprises people. The liver prioritises clearing alcohol over releasing glucose, so the risk is not at the time of drinking but hours later, often overnight. And exercise can lower glucose for many hours afterwards, which is covered in our piece on what activity actually does to the number.

A hypo is information. One is a reason to look at the pattern. Repeated ones mean the regimen is wrong, and the regimen is a thing that can be changed.