Diabetic ketoacidosis

Ketoacidosis is where a shortage of insulin ends up when nobody notices it in time. Glucose stops reaching the cells, the body falls back on burning fat, and acids called ketones build up until the blood itself turns acidic. The whole thing develops over hours, it is treated in hospital and nowhere else, and it remains one of the few reasons people still die of diabetes. The encouraging part is that almost every case is preceded by two or three recognisable days in which it can still be headed off at home or by phone.

What is going on inside

Insulin works like a key: without it, glucose stays in the bloodstream instead of getting into the cells. The cells starve in the middle of plenty, so the body turns to fat, a fuel that needs no key. Ketones are what is left over from burning it. Small amounts are harmless and appear in anyone who has gone a while without food, but with no insulin around nothing switches production off, and the acidity passes the point at which the heart and the body's enzymes work properly.

A second process runs alongside. The kidneys clear the surplus glucose into the urine, water follows it out, and that is where the thirst and the litres of urine come from. Several litres of fluid go over a day or two, and potassium with them. Vomiting doubles the speed of everything, since now nothing can be kept down. It is the dehydration and the potassium loss, rather than the high readings themselves, that make ketoacidosis life-threatening.

Type 1 diabetes is the usual setting, including as the very first sign of the illness in a child who has not yet been diagnosed. Type 2 is not exempt: it happens in people already using insulin, during a severe infection, and with certain glucose-lowering tablets.

How it looks from the outside

The picture assembles itself over a few hours, occasionally over a day. In children, and in anyone on a pump, faster.

• Thirst that nothing satisfies, and passing urine every hour, through the night as well.
• Nausea, vomiting and abdominal pain, sometimes bad enough to be taken for appendicitis.
• Breathing that turns deep, noisy and laboured, as if the person had just been running, while they are lying still.
• Acetone on the breath: sharp and sweetish, like nail varnish remover.
• Dry skin and cracked lips, sunken eyes, weakness.
• Drowsiness, slowed responses, difficulty putting a sentence together.
• Blurred vision, and sometimes cramp in the calves from the loss of salts.

One combination is worth memorising on its own: high glucose plus vomiting. In a person with diabetes that counts as ketoacidosis until proved otherwise, and blaming the vomiting on something they ate is not an option here.

When to call an ambulance

Do not wait for morning and do not try to see it through at home if even one of these is present:

• blood ketones above 3 mmol/L, or two or more pluses on a urine strip;
• vomiting that makes it impossible to drink or to cover food with insulin;
• deep noisy breathing, acetone on the breath, confusion or drowsiness;
• glucose that stays high after two correction doses of rapid-acting insulin in a row;
• severe abdominal pain;
• the same symptoms in someone never diagnosed with diabetes: thirst, weight loss, passing a lot of urine, and now vomiting and drowsiness on top;
• ketones high while the glucose is normal or only slightly raised, which is dealt with below and is the most treacherous version of all.

Nobody in this state should be driving, because consciousness can go on the way. Ask someone to take you or call an ambulance; in most European countries that is 112. Bring your insulin, your meter and a list of everything you take, and be sure the doctor gets the names of your diabetes tablets.

Ketones: what to measure them with and what the numbers mean

There are two ways to measure ketones. Urine strips are cheap and sold in every pharmacy, but they report yesterday: the substance they react to reaches the urine late and clears from it late as well. Meters that read ketones from a drop of blood cost more and show the situation as it stands right now, and it is those readings that decide whether someone goes to hospital. Anyone on insulin is better off keeping such a meter at home, and for the family of a child with diabetes it is not optional.

The accepted landmarks for blood run like this. Under 0.6 mmol/L is ordinary background. From 0.6 to 1.5 is raised, and calls for water, a correction dose along your own plan and a repeat reading two hours later. From 1.5 to 3 means you are already on your way to ketoacidosis and need to speak to a doctor the same day. Above 3 the clock is running in hours, and that is an ambulance.

The figures are approximate, and meters from different manufacturers disagree slightly, so it is better to settle your personal thresholds with your doctor in advance rather than at the point where you are already being sick. Four situations are worth measuring in: glucose above 14 mmol/L twice in a row, any illness with a fever, vomiting or diarrhoea whatever the glucose is doing, and simply feeling awful for no reason you can explain.

What sets ketoacidosis off

It hardly ever arrives out of nowhere; usually one of the following is behind it:

• an infection, anything from flu and pneumonia to a urinary infection or an abscess in a tooth: the need for insulin rises while the person cuts the dose because they are not eating;
• doses missed or deliberately reduced, insulin that ran out, a cartridge spoilt by heat;
• a pump failure: a kinked cannula, an inflamed site, a dressing that came unstuck. A pump holds no reserve of long-acting insulin, so ketones show up within a few hours;
• type 1 diabetes starting for the first time and being read as a stomach bug or as weight loss from stress;
• a heart attack, a stroke, an injury, surgery, severe stress;
• glucocorticoids, the hormone drugs given for inflammatory conditions, which push the insulin requirement up sharply;
• alcohol, particularly on top of several days without a proper meal;
• pregnancy, in which ketoacidosis develops faster and at lower glucose levels.

One variant deserves a paragraph of its own, rare but genuinely dangerous: ketoacidosis with normal glucose. It occurs in people taking SGLT2 inhibitors, also known as gliflozins, the tablets that clear surplus glucose through the urine and are prescribed in type 2 diabetes and sometimes in heart and kidney disease. The meter looks reassuring, showing 8, 10 or even 6, while the ketones climb behind it. Calm numbers reassure patient and doctor alike, and the diagnosis arrives late. If you take these tablets, remember one thing: nausea, vomiting, breathlessness or unexplained weakness are a reason to measure ketones rather than glucose, and to say out loud which drug you are on. The risk is highest around fasting, dehydration, alcohol and surgery, which is why these tablets are usually stopped some days before a planned procedure.

What hospital does

The treatment is well worked out and much the same everywhere. Saline goes up first to replace the missing litres. Rapid-acting insulin then runs in continuously through a drip in small doses, the aim being not to crash the glucose but to bring ketone production gently to a halt. Potassium is watched separately and very closely. While insulin was short, potassium leaked out of the cells and was lost in the urine; the moment insulin starts, what remains rushes back inside the cells and the blood level can drop to figures that threaten the heart, so potassium goes into the drip and is rechecked every few hours.

The cause is hunted down in parallel: blood tests, a chest film, a tracing of the heart, cultures. In children and teenagers there is a particular fear of swelling of the brain, so fluid is given by calculation rather than by the more-and-faster instinct. Once the ketones are down to safe levels, the acidity has evened out and the person can eat and drink again, the drip comes down and the usual injections take over, which normally takes one to three days.

The conversation before discharge is the most useful part of the whole admission. It is worth going through honestly with the doctor what actually happened: the insulin ran out, an infection went unnoticed, injecting felt wrong with no appetite. A second episode nearly always replays the first.

Sick days: the rules that prevent most cases

A cold, food poisoning, a temperature. That is the commonest opening, and everyone on insulin should have a plan for it agreed with their doctor in advance. The general logic goes like this:

• basal insulin is never stopped, even when nothing at all is being eaten. Skipping it is the single step that most often ends in intensive care;
• glucose every two to four hours, ketones whenever the glucose is high and whenever there is vomiting;
• drink little and often: water while the glucose is high, sweet drinks in small sips when it is low;
• if solid food will not go down, carbohydrate comes in liquid form instead, as juice or sweet tea;
• extra correction doses of rapid-acting insulin follow the plan you were given, never guesswork;
• on a pump, high glucose with ketones means insulin by pen without waiting for the pump to sort itself out, and the whole set gets changed;
• having somebody else in the house helps, because a person sliding into confusion is no longer a fair judge of their own state.

Keep a reserve of both kinds of insulin at home, a working meter with strips, an in-date ketone test and your doctor's number written down somewhere findable. Check the expiry date on the ketone strips every few months: they sit unused for years and go out of date precisely on the day they are needed.

Online consultation

Remotely it is easy to do the things that usually get put off: writing down a personal sick-day plan, making sense of the readings from your glucose meter and your ketone meter, working out at which numbers you add insulin and how many units. A doctor can go through your regimen with you, explain how to adjust doses during a fever or vomiting, and cover what changes if you take tablets that allow ketoacidosis at normal glucose. An episode that has already happened belongs here too: why it occurred and what to do differently. What cannot be done through a screen is treating ketoacidosis itself, and high ketones, vomiting or confusion mean an ambulance.

This material is for information only and does not replace medical advice.