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DIABETES SERIES · ARTICLE 8 OF 17

Hypoglycaemia

Recognising and treating low blood sugar.

Most diabetes articles focus on blood sugar being too high. This one is about the opposite — blood sugar dropping too low. It's called hypoglycaemia, “hypo” for short, and it's the most underestimated risk for anyone on insulin or certain tablets.

A hypo can come on in minutes. It can make you confused before you realise something is wrong. Severe hypos can cause seizures, accidents, even death. But the good news is: a hypo is almost always preventable, almost always reversible, and almost always treatable in under 15 minutes by something as simple as a glass of juice.

This article shows you how to recognise a hypo early, treat it quickly, and prevent it from happening in the first place. If you or someone in your family is on insulin or sulfonylurea tablets, read this carefully. Print it. Share it.

This is critical safety information

If you take insulin, glibenclamide, gliclazide, glimepiride, or any other sulfonylurea, you should know everything in this article. Hypoglycaemia is the single biggest medication-related risk in diabetes. Knowing what to do takes 10 minutes to learn and can save your life.

What hypoglycaemia is — and isn't

Hypoglycaemia is blood sugar that has dropped below 3.9 mmol/L. Some clinics use 4.0. Either way, the principle is the same: blood sugar has fallen below the level your brain needs to work properly.

Your brain runs almost entirely on glucose. When blood sugar drops, the brain notices fast. It sends out warning signals — shaking, sweating, hunger, a racing heart — to tell you to eat. If you don't eat, the brain itself starts to struggle. That's when confusion, slurred speech, and eventually unconsciousness happen.

A hypo is NOT just feeling tired, or having a bad day, or being moody. It is a measurable drop in blood sugar that the body responds to physically and predictably. If you have a meter, a finger-prick test confirms it in seconds.

The simple rule

If in doubt, treat. If a person on insulin or sulfonylureas suddenly feels strange, the safest action is to assume it's a hypo and eat fast sugar. The “cost” of treating a hypo that wasn't one is a few extra grams of sugar. The cost of not treating one that was is potentially catastrophic.

Who's at risk

Not everyone with diabetes is at risk of hypos. The risk depends almost entirely on your treatment.

Treatment Hypo risk

Insulin (any type) High. Insulin works whether you've eaten or not — too much can drop blood sugar dangerously. Sulfonylureas (glibenclamide, gliclazide, glimepiride) High. These tablets push the pancreas to release insulin even when blood sugar is already low. Glinides (repaglinide, nateglinide) Moderate. Similar to sulfonylureas but shorter-acting. Metformin alone Very low. Metformin works differently — does not cause hypos on its own. DPP-4 inhibitors (sitagliptin, vildagliptin) Very low on their own. Higher when combined with insulin or sulfonylureas. SGLT2 inhibitors (empagliflozin, dapagliflozin) Very low on their own. Higher in combination. GLP-1 agonists (liraglutide, semaglutide) Very low on their own. Diet and exercise only Essentially zero.

If you don't know what medication you're on, look at the box or ask your clinic. Then check this list. If you're in the “high risk” categories, the rest of this article is essential.

Warning signs — early and late

Hypo symptoms come in stages. Catching them early gives you time to fix the problem easily. Missing the early signs means you have to deal with the later ones — and the later they get, the harder they are to manage.

Early warning signs (3.0–3.9 mmol/L)

These are how your body shouts for sugar. They are usually felt as a combination — not all at once, but enough to know something is happening.

• Shaking or trembling hands

• Sweating (sometimes a cold, clammy sweat)

• Hunger — sudden and intense

• Heart racing or palpitations

• Anxiety or feeling jittery

• Tingling lips or tongue

• Dizziness or light-headedness

• Headache

• Pale skin

Late warning signs (below 3.0 mmol/L)

If a hypo isn't treated, blood sugar keeps falling. Now the brain itself isn't getting enough fuel. These symptoms mean you need fast sugar AND someone to help if possible:

• Confusion or difficulty concentrating

• Slurred speech

• Blurred or double vision

• Weakness or feeling like your legs won't work

• Mood changes — irritability, aggression, crying for no reason

• Drowsiness

• Acting drunk (people sometimes mistake severe hypos for being drunk)

Severe hypoglycaemia

If blood sugar drops further, the person may lose consciousness, have a seizure, or be unable to swallow. They cannot help themselves. Someone else has to act. This is an emergency.

If someone is having a severe hypo

Do NOT put food or liquid in their mouth — they can choke.

Turn them on their side (recovery position).

Call an ambulance or get them to a hospital immediately.

If you have a glucagon injection or nasal glucagon, use it — it is designed exactly for this. Most public clinics don't stock glucagon routinely; private prescriptions are available.

The 15-15 rule for treating a hypo

If you (or someone you're with) is conscious and able to swallow, the 15-15 rule is the international standard:

Step What to do

1. Eat or drink 15 grams of fast-acting sugar. 2. Wait 15 minutes. 3. Re-test blood sugar. If still under 4.0 mmol/L, eat another 15 g and wait another 15 minutes. 4. Once blood sugar is back above 4.0, eat a small snack with protein and slow carbs (e.g. a sandwich with peanut butter) to keep it stable until the next meal.

What counts as 15 g of fast sugar?

All of these are roughly equivalent. Keep at least one of them with you at all times if you're at risk:

• 3 glucose tablets (the kind sold at any pharmacy)

• Half a glass (about 100 ml) of fruit juice or regular cold drink (not diet)

• 1 tablespoon of honey or jam

• 3–4 normal sweets (Smarties, jelly babies — not chocolate, which is too slow because of the fat)

• 1 small tube of glucose gel (especially useful for children or someone semi-conscious who can still swallow)

• 4 teaspoons of sugar dissolved in a little water

Why not chocolate?

Chocolate seems like an obvious choice — it's sugary. But the fat in chocolate slows down how quickly the sugar reaches your blood. In a hypo you need fast action. Save chocolate for after a hypo is treated, not during one.

Why hypos happen

Almost every hypo has a cause. Identifying the cause helps prevent the next one.

• Too much insulin or medication. A dose too big for the amount of food eaten, or accidentally taking a dose twice.

• Skipping or delaying a meal. You took the insulin but didn't eat enough, or didn't eat on time.

• Eating less than expected. The meal you planned was bigger than what you actually ate.

• More exercise than usual. Walking up a hill, gardening for an hour, a longer-than-usual walk — all burn more glucose.

• Alcohol. Alcohol prevents the liver from releasing stored glucose. Drinking on an empty stomach is the biggest cause of severe hypos in adults.

• Hot weather or hot baths. Heat speeds up insulin absorption from injection sites.

• Recent illness or infection clearing up. During illness you may have needed more insulin. After recovery you may need less — the doses can lag.

• Weight loss. A smaller body needs less insulin. Medication doses should be reviewed as you lose weight.

Preventing hypos

Most hypos can be avoided with five simple habits:

• 1. Don't skip meals. Especially after taking insulin or sulfonylureas. If you must delay a meal, eat a small snack with carbs to bridge the gap.

• 2. Test before exercise and before driving. If you're under 5.5 mmol/L, eat a small snack first. Never drive with blood sugar below 5.0.

• 3. Carry fast sugar everywhere. In your bag, your car, your bedside table, your work desk. The single most important thing on this list.

• 4. Tell people around you. Family, colleagues, a close friend — they should know you have diabetes, what a hypo looks like, and where you keep your sugar.

• 5. Adjust for the day. More exercise than usual, less food, hot weather, alcohol — these all increase hypo risk. If you know they're coming, eat a bit more or take a bit less (with clinic guidance for medication adjustments).

Hypoglycaemia unawareness

Some people who've had diabetes for many years stop feeling early warning signs. The body no longer shouts for sugar — it goes straight from “fine” to “confused”. This is called hypoglycaemia unawareness, and it's dangerous because there's much less time to react.

It happens for two main reasons:

• Long-standing diabetes — over years, the body's early-warning system can dull

• Frequent hypos — having lots of small hypos teaches the brain to ignore the warning signs

If you find yourself surprised by sudden confusion or weakness — without the shaking and sweating you used to get — talk to the clinic. Strategies include avoiding low blood sugars for a few weeks to “reset” the warning system, using continuous glucose monitoring, and adjusting medication targets upward.

Nighttime hypos — the hidden danger

Hypos that happen during sleep are especially dangerous because you may not wake up, or you may wake up confused and unable to act. Warning signs the next morning include:

• Waking up with a headache

• Damp sheets from sweating

• Feeling “off” or tired despite a full night's sleep

• Unusual dreams or restless sleep

• Higher-than-expected morning blood sugar (the body's rebound response to a nighttime low)

If you suspect nighttime hypos, set an alarm to test at around 3 AM for a few nights. Talk to the clinic — they may adjust your evening insulin dose, recommend a snack before bed, or suggest a CGM.

What family and friends need to know

People around you can save your life if they know what to do. Brief everyone close to you — partner, parents, adult children, close colleagues — on these three things:

• 1. Recognise the signs. Shaking, sweating, confusion, acting drunk. If they see these in someone they know has diabetes, treat it as a possible hypo.

• 2. Help with sugar. If the person is conscious and can swallow, get them juice, sweets, or glucose. If they can't swallow, do NOT put anything in their mouth — turn them on their side and call for help.

• 3. Know where the supplies are. Glucose tablets in your bag, juice in the fridge, glucagon (if you have it) in a specific drawer. Show them.

A medical ID is one of the cheapest, most powerful tools

A simple medical ID bracelet or necklace says “Type 1 diabetes — give sugar in emergency”. They cost under R200 online or at most pharmacies.

If something happens away from family — a hypo on a taxi, a collapse in the street — paramedics and bystanders will know what to do.

The bigger picture

Hypoglycaemia is the single biggest fear most people on insulin live with. It is also one of the most preventable problems in diabetes. Understanding the signs, keeping sugar nearby, telling people who can help — these are not complicated steps. They are the kind of preparation that lets you live a normal life with diabetes instead of constantly worrying about emergencies.

Most people will go years without a serious hypo. A few will have small ones now and then. The skill is not avoiding every single one — it's catching them early, treating them quickly, and learning what caused each one so the next is less likely.

The next article in this series moves into the topic that affects the most people in the long run: looking after your feet. Diabetic foot complications are one of the leading causes of amputation in South Africa, and yet almost all of them are preventable with daily care.

Where to get more help

Diabetes South Africa — diabetessa.org.za · 011 792 9888

In an emergency — 10177 for an ambulance, or your nearest hospital emergency department

Phila Today Diabetes Series — next: looking after your feet when you have diabetes

Phila Today · Article 8 of 17 in the Diabetes Series