Type 2 Diabetes Losing Control: Hypos, Hyperglycaemic Emergencies and When the Tablets Stop Working
Diabetes control is a range, and it can fail at either end. Most attention goes to glucose climbing, which is slow and silent. The other end arrives in minutes and is the one that puts people in hospital this week rather than in ten years.
This page is about recognising both, and about the third thing nobody names: the point at which a treatment regimen has quietly stopped working and nobody has changed it. Choosing the drugs themselves is covered in our guides to starting treatment and adding a second drug.
📊 The numbers, since the article you read probably did not give them
| Test | Diabetes is diagnosed at | Prediabetes range |
|---|---|---|
| Fasting plasma glucose | 7.0 mmol/L (126 mg/dL) or above | 5.6 to 6.9 mmol/L (100 to 125) |
| HbA1c | 6.5 percent (48 mmol/mol) or above | 5.7 to 6.4 percent (39 to 47) |
| 2-hour glucose tolerance test | 11.1 mmol/L (200 mg/dL) or above | 7.8 to 11.0 (140 to 199) |
| Random glucose with symptoms | 11.1 mmol/L (200 mg/dL) or above | — |
Two readings on separate occasions are needed unless symptoms are unmistakable. And the treatment target for most adults is below 7 percent (53 mmol/mol), relaxed to 7.5 or 8 percent in older age, frailty, limited life expectancy or where hypoglycaemia has already occurred — which is the subject of the next section.
🔻 The low end: hypoglycaemia
Among oral diabetes drugs, only the sulfonylureas and the meglitinides cause this. Metformin, the SGLT2 inhibitors and the DPP-4 inhibitors do not, on their own. If you take glimepiride, glipizide or gliclazide, this section is about you.
| Level | Glucose | What it means |
|---|---|---|
| Level 1 | Below 3.9 mmol/L (70 mg/dL) | Alert value. Treat it, and tell your clinician it happened |
| Level 2 | Below 3.0 mmol/L (54 mg/dL) | Clinically significant. The regimen needs changing, not just the snack |
| Level 3 | Any level requiring another person to help | Severe, regardless of the number. Always reported |
What it feels like: shaking, sweating, hunger, pounding heart, anxiety and pallor first; then difficulty concentrating, slurred speech, irritability or unusual behaviour, blurred vision, and finally confusion, seizure or unconsciousness. People around you often notice the second group before you do.
🍬 The 15-15 rule, which is the whole of first aid for this.
1. Take 15 g of fast-acting carbohydrate. That means 3 to 4 glucose tablets, 150 ml of fruit juice or ordinary (not diet) cola, or a tablespoon of sugar or honey.
2. Wait 15 minutes and re-check. Do not keep eating in the meantime — the commonest error is treating a hypo with everything in the kitchen and spending the rest of the day very high.
3. Still below 3.9? Repeat the 15 g.
4. Once recovered, eat a longer-acting carbohydrate — a sandwich, toast, biscuits — if the next meal is more than an hour away.
Not chocolate. The fat slows absorption, which is exactly wrong in the one situation where speed matters.
🚨 Severe hypoglycaemia — someone confused, fitting or unconscious.
Nothing by mouth. Do not pour drinks or push gel into the mouth of someone who cannot swallow safely. Place them on their side, give glucagon by injection or nasal spray if available, and call emergency services.
Anyone at risk should have glucagon at home and at least one household member who knows where it is and how to use it. It is a five-minute conversation that occasionally saves a life.
⏳ Why a sulfonylurea hypo is different
This matters and it is routinely missed. Insulin hypos end when the insulin wears off. Sulfonylurea hypos can last many hours and recur after apparently successful treatment, because the drug keeps stimulating insulin release long after the sugary drink has gone. Glimepiride in particular has a long duration of action.
So a severe hypo caused by a sulfonylurea usually needs hospital observation rather than a sweet drink and reassurance, especially in older people and in anyone with reduced kidney function. The same applies to accidental overdose in a child, which is a hospital matter every time.
🔍 What makes a hypo likely
- 🍽️ A missed, delayed or smaller meal after taking the tablet. The commonest cause by far
- 🍷 Alcohol, particularly without food, and the effect can arrive many hours later — overnight hypos after an evening out are a recognised pattern
- 🏃 Unplanned or unusually hard exercise, with the risk extending into the following night
- 🫀 Declining kidney function, which slows clearance of the drug. A hypo that appears out of nowhere after years of stability often means the kidneys have changed
- 👴 Older age, where symptoms are blunted and consequences are worse
- 💊 Drug interactions — some antibiotics, antifungals and others raise sulfonylurea levels
- ⚖️ Weight loss, which reduces the dose requirement and is frequently not followed by a dose reduction
⚠️ Hypoglycaemia unawareness. After repeated lows, the warning symptoms fade and the first sign becomes confusion — by which point you cannot treat yourself. It is dangerous and it is reversible: strictly avoiding lows for several weeks restores the warnings. If you have stopped feeling your hypos, say so, because it changes both the target and the treatment.
🚗 Driving
- 🔢 Check before driving. The widely used rule is 5 to drive — at or above 5.0 mmol/L (90 mg/dL) before setting off
- 🍬 Carry fast carbohydrate within reach, not in the boot
- 🛑 If you feel low while driving: stop safely, remove the keys, move out of the driver seat, treat it, and wait 45 minutes after glucose has returned to normal before driving again. Cognitive function recovers more slowly than the blood test
- 📋 Check on long journeys every two hours
- ⚖️ Severe hypoglycaemia requiring help from another person generally must be declared to the licensing authority, and the rules differ by country and by licence type — check your own
🔺 The high end: the emergency most people have never heard of
Everyone knows about diabetic ketoacidosis. In type 2 diabetes the more typical crisis is a different one.
🚨 Hyperosmolar hyperglycaemic state. Glucose climbs extremely high — often above 33 mmol/L (600 mg/dL) — over days rather than hours, pulling water out of the body through the kidneys until severe dehydration sets in. Ketones stay low or absent, so urine ketone sticks are reassuring and wrong.
The signs: intense thirst, passing large volumes of urine then producing very little, dry mouth and skin, weakness, and progressive drowsiness and confusion. Sometimes focal weakness or seizures that look like a stroke.
It usually has a trigger: an infection, missed medication, a course of steroids, a stroke or heart attack. Mortality is higher than for ketoacidosis, largely because it builds slowly and gets attributed to ageing or a urine infection.
Confusion or marked drowsiness in someone with type 2 diabetes is an emergency call, not an appointment.
And ketoacidosis does occur in type 2 diabetes, with one specific trap: people taking an SGLT2 inhibitor can develop it with a nearly normal glucose reading. Nausea, vomiting, abdominal pain or deep rapid breathing on one of those drugs needs emergency assessment whatever the meter says, and the treating team must be told which drug you take.
📉 When the tablets have stopped working
This is the quiet failure. HbA1c drifts above target, each review notes it, and nothing changes. The average delay between a rising HbA1c and an actual treatment change is measured in years, and every one of those years is accumulating damage.
- 📅 HbA1c above your agreed target on two consecutive checks is the trigger to change something, not to try harder for another six months
- 📈 Sulfonylureas lose effect over time. They work by pushing the pancreas to release more insulin, and as beta-cell function declines there is less to push. Secondary failure after several years is expected rather than a personal failing
- 🔍 Before escalating, check the ordinary things — are the tablets actually being taken, has weight changed, is there an infection, has a steroid course been started, is there untreated sleep apnea or depression
- 🎯 Then change by mechanism, adding a drug that does something the current one does not. The choice is driven by heart and kidney status, which is set out in our combination therapy guide
- 📝 Ask for your actual number and your actual target at every review. Treatment that is never measured against a target does not get changed
💊 Glimepiride in practice
Amaryl (Glimepiride) is a third-generation sulfonylurea. It lowers HbA1c by roughly 1.0 to 1.5 percent, which is as much as any oral drug, and it is inexpensive. Its place in current practice is as an add-on where the first-line agent is insufficient, or where cost, availability or tolerance rules out the alternatives — not as the step after lifestyle measures.
- 🔹 Start 1 mg daily with breakfast, or the first main meal. 1 mg in older people and in reduced kidney function
- ⬆️ Increase in 1 mg steps at intervals of one to two weeks, to a usual 1 to 4 mg daily. Doses above 4 mg add little and add hypoglycaemia
- 🍽️ Always with food. Taking it and then skipping the meal is the classic route to a hypo
- ⚖️ Expect some weight gain, which is a real drawback of the class
- 🚫 Not in severe kidney or liver impairment, and not in type 1 diabetes or ketoacidosis
- 📉 If you lose weight or become more active, the dose usually needs reducing. This is the point at which long-stable people have their first hypo
- 🌡️ Hold it during vomiting, diarrhoea or any illness where you cannot eat — part of the sick day rules in our combination therapy guide
Glipizide is the alternative in the same class, and the full range is in the diabetes category.
📋 Monitoring that answers a question
Testing without a question attached produces anxiety and no information. Testing with one changes something.
| Question | When to test |
|---|---|
| Is my background control drifting? | Fasting, a few mornings in a row, periodically |
| What does this particular meal do to me? | Two hours after starting the meal. Aiming below about 10 mmol/L (180 mg/dL). This is how you learn which foods are the problem, and it is more useful than cutting everything |
| Am I having hypos I do not notice? | Before driving, before bed, and during the night if there are morning headaches or night sweats |
| Am I safe to drive? | Every time, if on a sulfonylurea |
| Is something acute going on? | More often during any illness, and HbA1c every three to six months while treatment is changing |
👁️ The checks that prevent what this is all for
Glucose control is one axis. These are what stop the complications that actually disable people, and gaps in this list are where diabetes care usually fails.
- 👁️ Retinal photography every year — eye disease is silent until it is advanced and treatable before that
- 🦶 Feet examined every year, more often with numbness. Loss of sensation plus a minor injury is how amputations start
- 🧪 Urine albumin-to-creatinine ratio and eGFR yearly — protein appears long before function falls and it changes the drug choice
- 🩸 Blood pressure at every visit, which prevents more complications in diabetes than tightening glucose does
- 📉 Lipids, with a statin for most people over 40 regardless of the cholesterol number
- 💉 Influenza, pneumococcal and COVID-19 vaccination
- 🦷 Dental review, since gum disease and glucose control worsen each other
📞 When to seek help
Emergency:
- Confusion, marked drowsiness or unresponsiveness in anyone with diabetes — either end of the range can cause it
- A hypo needing another person to help, or one not responding to two rounds of 15 g
- Any severe hypo on a sulfonylurea — these recur, and observation is needed
- Glucose above 30 mmol/L (540 mg/dL) with drowsiness, very dry mouth and reduced urine output
- Nausea, vomiting, abdominal pain or deep rapid breathing on an SGLT2 inhibitor — even with a normal glucose reading
- Chest pain, or sudden weakness or speech difficulty
Promptly:
- More than one hypo a week, or any hypo below 3.0
- No longer feeling your hypos coming
- HbA1c above target on two checks with no change to the plan
- A new hypo pattern after years of stability — ask for kidney function to be checked
- Any foot ulcer, blister, cut or colour change — the same week
- Blurred or changing vision
- No sick day instructions in writing, or no retinal, foot and urine checks in the past year
- Weight loss, more activity, or a new medicine while on a sulfonylurea — the dose may need reducing
❓ Frequently asked questions
What is the 15-15 rule for low blood sugar?
Take 15 g of fast carbohydrate — three or four glucose tablets, 150 ml of juice or ordinary cola, or a tablespoon of sugar — wait 15 minutes, re-check, and repeat if still below 3.9 mmol/L. Then eat longer-acting carbohydrate if the next meal is over an hour away.
Why should I not use chocolate to treat a hypo?
The fat in chocolate slows sugar absorption, which is exactly wrong when speed is the point. Glucose tablets, juice or ordinary cola act within minutes; chocolate does not.
Which diabetes tablets cause low blood sugar?
Only sulfonylureas such as glimepiride, glipizide and gliclazide, and the meglitinides. Metformin, SGLT2 inhibitors and DPP-4 inhibitors do not cause it on their own.
Why does a sulfonylurea hypo need hospital observation?
Because the drug keeps stimulating insulin release for many hours after the sugary drink has gone, so lows recur after apparently successful treatment. This is unlike an insulin hypo and it is routinely underestimated.
What glucose level is safe to drive at?
At or above 5.0 mmol/L, about 90 mg/dL, before setting off, with fast carbohydrate within reach. After treating a hypo, wait 45 minutes beyond normal glucose before driving, since thinking recovers more slowly than the reading.
What is hypoglycaemia unawareness?
Loss of the warning symptoms after repeated lows, so the first sign becomes confusion — too late to self-treat. It is reversible by strictly avoiding lows for several weeks, and it should always be reported because it changes the target.
What is hyperosmolar hyperglycaemic state?
A type 2 emergency where glucose climbs above about 33 mmol/L over days with severe dehydration and confusion, and ketones stay low so ketone sticks are falsely reassuring. Mortality is higher than for ketoacidosis.
What is the glimepiride dose?
Start 1 mg daily with breakfast, increasing in 1 mg steps every one to two weeks to a usual 1 to 4 mg. Above 4 mg adds little benefit and more hypoglycaemia. Always taken with food.
I have been stable for years and suddenly had a hypo. Why?
Commonly because kidney function has declined and the drug is clearing more slowly, or because of weight loss, more activity, less food or a new interacting medicine. Ask for kidney function to be checked and the dose reviewed.
How do I know my treatment has stopped working?
HbA1c above your agreed target on two consecutive checks. That is the trigger to change something rather than try harder for another six months. Sulfonylureas in particular lose effect over years as insulin production declines.
📑 Sources and editorial
- Diagnostic criteria for diabetes and prediabetes by fasting glucose, HbA1c and oral glucose tolerance testing
- American Diabetes Association standards of care, including individualised HbA1c targets and the classification of hypoglycaemia into levels 1, 2 and 3
- Guidance on the recognition and treatment of hypoglycaemia, including the 15-15 approach and the use of glucagon in severe episodes
- Reviews of prolonged and recurrent hypoglycaemia associated with sulfonylureas, and recommendations for observation after severe episodes
- Driving guidance for people treated with hypoglycaemia-causing agents, including pre-driving glucose thresholds and post-hypoglycaemia waiting periods
- Guidance on hyperosmolar hyperglycaemic state in adults, including presentation, precipitants and outcomes, and on euglycaemic ketoacidosis with SGLT2 inhibitors
- Prescribing information for glimepiride and glipizide, including initiation in older adults and renal impairment
- Studies of therapeutic inertia and the interval between HbA1c exceeding target and treatment intensification
- Evidence on secondary failure of sulfonylurea therapy with declining beta-cell function
- Screening guidance for diabetic retinopathy, foot disease and diabetic kidney disease
- Related reading: starting treatment in type 2 diabetes, combination therapy and sick day rules
- Related products: Amaryl (Glimepiride), diabetes category
- RXshop Editorial Team — reviewed by Daniel Kim, MD — Endocrinologist & Diabetes Specialist
Medical Disclaimer: The information in this article is for educational and informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek guidance from a qualified healthcare provider with any questions you may have regarding a medical condition, and before starting, stopping or changing any medication.