Diabetic ketoacidosis — recognizing the symptoms early

Diabetic ketoacidosis (DKA) kills people who did not recognise it in time. The prodrome — the 12–24 hours before glucose exceeds 250 mg/dL and blood pH falls below 7.3 — is when intervention is simple and outpatient. The fully developed syndrome is an emergency requiring IV fluids, insulin infusion, and electrolyte replacement in a hospital setting. DKA occurs when insulin is absent or severely insufficient: the body, unable to use glucose for fuel, begins breaking down fat into ketone bodies (acetoacetate, beta-hydroxybutyrate, acetone) at a rate that acidifies the blood. It is most common in Type 1 diabetes but occurs in Type 2 under conditions of severe physiologic stress — sepsis, myocardial infarction, surgery. Managing diabetes complications starts with knowing which warning signs to act on immediately. The early warning signs are specific: blood glucose persistently above 250 mg/dL, moderate to large urinary ketones on a dipstick, nausea, abdominal pain, and a fruity or acetone smell on the breath. Per ADA Standards of Care 2024 §16, anyone with Type 1 diabetes should have access to urine or blood ketone testing supplies and should test whenever glucose exceeds 250 mg/dL for more than two consecutive readings. People observing religious fasting — including those following a Ramadan fasting protocol — face elevated DKA risk and should have this monitoring protocol clearly in place. This guide maps the symptom progression from the early warning window through critical presentation so you can act before it becomes an emergency.

The physiology of DKA — what goes wrong inside the body

To understand why DKA’s symptoms appear in the order they do and why the window for easy intervention is so narrow, it helps to trace the biochemical cascade from its starting point.¹

In the presence of normal insulin levels, GLUT4 transporters on muscle and fat cells respond to insulin by translocating to the cell membrane, enabling glucose uptake. The brain uses a different transporter (GLUT1/GLUT3) that does not require insulin, making it dependent on blood glucose concentration rather than insulin directly. When insulin is absent or severely deficient, peripheral cells cannot absorb glucose despite blood glucose being elevated — the body is effectively starving at the cellular level even while glucose accumulates in the blood.

In this insulin-deficient state, hormone-sensitive lipase (HSL) is no longer inhibited. HSL breaks down triglycerides in adipose tissue into free fatty acids (FFAs) and glycerol. FFAs flood the portal circulation and reach the liver in concentrations far exceeding normal. The liver, also uninhibited by insulin, converts these FFAs through beta-oxidation into acetyl-CoA. Under normal conditions, acetyl-CoA enters the Krebs cycle for energy production. But when glucose is unavailable and insulin is absent, the liver’s oxaloacetate supply is diverted to gluconeogenesis, leaving insufficient oxaloacetate to accept acetyl-CoA into the Krebs cycle. The excess acetyl-CoA is shunted into ketogenesis: acetoacetate, beta-hydroxybutyrate, and acetone.

These ketone bodies are weak acids. As they accumulate in the blood — from normal physiological concentrations of under 0.5 mmol/L to DKA levels of 3–30 mmol/L — they progressively acidify the blood, dropping pH below 7.35 (acidosis) and eventually below 7.3 (DKA threshold). The bicarbonate buffer system is overwhelmed. The compensatory respiratory response — Kussmaul breathing — begins to blow off CO2 to reduce carbonic acid and partially restore pH.¹

The brain, despite being a GLUT1-mediated consumer of glucose, is also affected. Brain function begins to deteriorate below a blood pH of approximately 7.2, contributing to the confusion, lethargy, and eventual coma of severe DKA. The kidney simultaneously attempts to excrete glucose and ketones in the urine, causing the profound osmotic diuresis (glucose in the tubular fluid draws water) that leads to dehydration — often 4–8 litres of fluid deficit by the time a patient reaches the emergency department.

Understanding this cascade explains why early intervention is so effective: at the first sign of elevated glucose and ketones, a corrective insulin dose and aggressive oral hydration can interrupt the cascade before pH falls, before dehydration becomes severe, and before the brain is compromised.

Early warning signs — the 12–24 hour recognition window

The earliest indicators of developing DKA appear before metabolic acidosis is established. This is the window in which outpatient self-management can potentially abort the episode without hospitalisation.²

Persistent hyperglycemia above 250 mg/dL. Two consecutive meter readings above 250 mg/dL — not explained by a known high-carbohydrate meal and not correcting with a standard correction dose — is the first actionable signal. Understanding the dawn phenomenon is important here: not every elevated fasting reading is DKA territory, but the two must be distinguished by checking ketones. In people using CGM, a glucose trace that has been above 200 mg/dL for more than 4 hours without trending down after a correction bolus should prompt a ketone check.

Increased thirst and urination. Glucose above the renal threshold (~180 mg/dL) spills into the urine, drawing water with it. The resulting osmotic diuresis creates thirst and frequent urination — symptoms that are easy to dismiss as non-specific, especially in hot weather or after exercise, but that in the context of persistently high glucose represent active fluid loss.

Moderate to large urinary ketones. Urine ketone dipstick testing (Ketostix or equivalent) showing “moderate” (2+) or “large” (3+) in a person with glucose above 250 mg/dL is the second critical signal. Small ketone readings (trace or 1+) may occur in the morning after overnight fasting or during exercise and are not independently alarming. Moderate or large ketones with persistent hyperglycemia require immediate action — do not wait for more symptoms.

At-home testing protocol:

1. Check blood glucose with meter or CGM
2. If glucose >250 mg/dL: check urine ketones with dipstick, or blood ketones with a ketone meter (beta-hydroxybutyrate meter, target <0.6 mmol/L normal, 0.6–1.5 moderate, >1.5 concerning, >3.0 DKA range)
3. If ketones are moderate or large: begin the sick-day protocol (see last section), drink 250 mL water immediately, administer a correction dose, and contact your care team within 2 hours
4. Recheck both glucose and ketones in 2 hours. If not trending down, go to the emergency department.

The classic triad — nausea, fruity breath, Kussmaul breathing

Once DKA has progressed beyond the early warning stage — typically when blood pH has fallen below 7.3 and ketone concentrations are substantially elevated — the classic clinical triad becomes apparent. These signs indicate that outpatient management has been missed or has been insufficient and that emergency care is likely required.^1,2

Nausea and vomiting. Gastrointestinal symptoms are among the most reliable clinical markers of established DKA. Ketone bodies directly irritate the gastric mucosa, and the acidic blood pH affects central nervous system nausea centres. Vomiting eliminates the possibility of oral rehydration and oral carbohydrate correction, which is why established DKA requires IV access. The irony is that nausea and vomiting are also common symptoms of other conditions — gastroenteritis, migraine, food poisoning — and are therefore easy to misattribute. In any person with diabetes who presents with nausea and vomiting, DKA must be ruled out with a ketone check before attributing symptoms to other causes. The related distinction between the Somogyi effect and the dawn phenomenon is another case where a single measurement cannot substitute for a systematic overnight pattern check.

Fruity or acetone breath. Acetone (one of the three ketone bodies) is volatile and is excreted in the breath, producing a characteristically sweet, fruity smell sometimes described as nail polish remover or overripe fruit. This sign is objective and notable to observers — family members or clinicians may detect it before the patient does. The absence of fruity breath does not rule out DKA (not all patients produce detectable breath acetone), but its presence in a symptomatic person with diabetes is clinically significant.

Kussmaul breathing. As blood pH falls below 7.3, the respiratory centre in the medulla oblongata responds to the metabolic acidosis by driving deeper, faster breathing — an attempt to blow off CO2 and reduce the carbonic acid contribution to blood acidity. Kussmaul breathing is characterised by: respiratory rate above 20 breaths per minute (sometimes reaching 30–40), deep and laboured breaths with visible expansion of the chest, and a sighing quality between breaths. It may not be detectable to the patient themselves but is apparent to observers. A family member describing “rapid, deep breathing” in a person with diabetes who is also vomiting and confused is describing a DKA emergency.

DKA triggers — illness, missed insulin, and the unexpected causes

DKA does not occur spontaneously in people who are taking adequate insulin. Every DKA episode has a trigger. Identifying the trigger after an episode — or recognising it in real time — is essential for prevention.³

Illness and infection. Physiologic stress from infection (particularly bacterial infections — UTIs, pneumonia, cellulitis) triggers a massive counter-regulatory hormone response: cortisol, glucagon, growth hormone, and epinephrine all rise, driving hepatic glucose production and lipolysis. Even a moderate dose of basal insulin may be insufficient to counteract this hormonal storm. Illness is the most common DKA trigger — it precipitates approximately 40% of episodes. Prevention requires the sick-day rule of never stopping insulin during illness, even if food intake is reduced.

Missed or inadequate insulin doses. The second most common trigger. This includes missed injections, incorrectly dialled doses, and insulin pump malfunctions (kinked cannula, empty reservoir, battery failure). For pump users, a cannula site failure can cause effective insulin cessation without any visible alarm. Any pump user who sees persistent hyperglycemia above 250 mg/dL should consider a site failure and administer a correction dose via injection rather than an additional pump bolus — if the site has failed, additional pump doses will not be delivered.

New-onset Type 1 diabetes. A significant proportion of first DKA presentations occur at the time of initial Type 1 diabetes diagnosis, before the diagnosis has been made. Symptoms of polyuria, polydipsia, and weight loss that have been present for weeks are followed by the acute DKA syndrome. DKA as the presenting feature of new T1D is more common in children but occurs at all ages.

SGLT2 inhibitors in Type 1 diabetes. Sodium-glucose cotransporter 2 inhibitors (dapagliflozin, empagliflozin, canagliflozin) are primarily approved for Type 2 diabetes but are sometimes used off-label in Type 1. They increase urinary glucose excretion, which can lower glucose without insulin — but they do not suppress ketogenesis. Euglycaemic DKA (DKA with relatively normal or only mildly elevated glucose) has been documented in T1D patients on SGLT2 inhibitors. Standard glucose-based DKA detection may fail in these cases because the glucose level does not trigger a ketone check.

Alcohol. Alcohol inhibits hepatic gluconeogenesis (risk of hypoglycemia) but can also precipitate ketoacidosis through a separate mechanism (alcoholic ketoacidosis) that overlaps clinically with DKA. Alcohol-associated DKA is more common in people with T1D who drink heavily, particularly when food intake is reduced.

When to go to the emergency department — hard thresholds

The following are absolute indications for emergency department attendance — do not wait, do not attempt further home management:^2,3

• Persistent vomiting preventing any fluid intake (oral hydration and oral correction are impossible; IV access required)
• Blood glucose above 300 mg/dL with large ketones not responding to a correction dose after 2 hours
• Blood ketones above 3.0 mmol/L (or large urine ketones with clinical symptoms)
• Kussmaul breathing — this indicates established metabolic acidosis; outpatient correction is no longer sufficient
• Confusion, disorientation, or altered consciousness — the brain is being affected by acidosis; immediate IV intervention required
• Chest pain or abdominal pain severe enough to prevent normal function — DKA can cause pseudo-peritonitis (abdominal rigidity without actual surgical pathology) but must be distinguished from true cardiac or abdominal emergencies that triggered the DKA

The moderate-stage decision: If glucose is above 250 mg/dL with moderate ketones and mild nausea, but you are still able to drink fluids and you can reach your care team by phone within 2 hours, managed home correction may be appropriate in coordination with your endocrinologist or diabetes educator. Do not make this decision alone. If you cannot reach your care team and symptoms are present, err toward emergency care.

DKA prevention — the sick-day rules every insulin user must know

Sick-day rules are the structured protocol that prevents illness-triggered DKA from escalating to hospitalisation. Every person with Type 1 diabetes should have these memorised before they get sick, because cognitive function during illness is impaired.³

The core rules:

1. Never stop insulin during illness. Even if you are not eating, your body needs basal insulin to prevent uncontrolled ketogenesis. Basal insulin should be continued at its normal dose unless specifically adjusted by your care team.
2. Switch to sugar-free or low-carbohydrate fluids if unable to eat. Broth, water, sugar-free electrolyte drinks. If glucose is already elevated, avoid regular juice or soda.
3. Check glucose and ketones every 2–4 hours while ill. Do not wait for symptoms to worsen before rechecking.
4. Increase correction insulin for persistent hyperglycemia. If glucose remains above 250 mg/dL after a standard correction dose, administer an additional correction after 2 hours per your care team’s sick-day protocol.
5. Contact your care team early. Call when moderate ketones first appear with persistent hyperglycemia — not after vomiting has begun. Most endocrinology practices have after-hours lines specifically for this scenario.
6. Have your emergency contacts aware. A family member or roommate should know your sick-day protocol and the signs that warrant calling emergency services if you are unable to do so yourself.

The JDRF’s sick-day management guidelines provide printable protocols that can be posted in a visible location in the home, reducing cognitive load during illness when retrieval of memorised information is impaired.

References

1. Kitabchi AE, Umpierrez GE, Miles JM, Fisher JN. “Hyperglycemic Crises in Adult Patients with Diabetes.” Diabetes Care 32, no. 7 (2009): 1335–1343.

2. American Diabetes Association Professional Practice Committee. “Diabetes Technology: Standards of Care in Diabetes—2024.” Diabetes Care 47, Supplement 1 (2024): S295–S306. Section 16.

3. Umpierrez GE, Korytkowski M. “Diabetic Emergencies — Ketoacidosis, Hyperglycaemic Hyperosmolar State and Hypoglycaemia.” Nature Reviews Endocrinology 12, no. 4 (2016): 222–232.

4. Dhatariya KK, Glaser NS, Codner E, Umpierrez GE. “Diabetic Ketoacidosis.” Nature Reviews Disease Primers 6, no. 1 (2020): 40.

5. Peters AL, Buschur EO, Buse JB, Cohan P, Diner JC, Hirsch IB. “Euglycemic Diabetic Ketoacidosis: A Potential Complication of Treatment with Sodium-Glucose Cotransporter 2 Inhibition.” Diabetes Care 38, no. 9 (2015): 1687–1693.