Blood Glucose Levels in DKA: Causes and Treatment

Blood glucose levels in DKA rise sharply and dangerously, often exceeding 20 mmol/L, as the body breaks down fat for fuel in the absence of sufficient insulin. Diabetic ketoacidosis (DKA) is a life-threatening emergency most common in type 1 diabetes, though it can affect anyone with diabetes during illness, infection or missed insulin doses. Understanding how glucose and ketone levels interact, how DKA is diagnosed, and when to seek emergency help is essential for people with diabetes, their families and carers.

What happens to blood glucose levels during DKA?

In DKA, blood glucose rises because absent insulin prevents cells absorbing glucose, while the liver continues releasing it and fat breakdown produces acidic ketones, causing metabolic acidosis.

In diabetic ketoacidosis (DKA), blood glucose levels rise sharply because the body lacks sufficient insulin to allow glucose to enter cells for energy. Without insulin, the body turns to breaking down fat as an alternative fuel source. This process produces acidic by-products called ketones, which accumulate in the blood and urine, lowering the blood's pH and creating a dangerous state of metabolic acidosis.

The mechanism begins when insulin levels fall critically low, most commonly in people with type 1 diabetes, though DKA can also occur in type 2 diabetes, particularly during illness, infection or significant physiological stress. Without insulin, the liver continues to release glucose into the bloodstream through two processes: glycogenolysis (the breakdown of stored glycogen) and gluconeogenesis (the production of new glucose), while cells remain unable to absorb it. The result is a simultaneous rise in blood glucose and ketone levels.

As glucose accumulates in the blood, it spills into the urine and draws water with it through osmotic diuresis, causing significant dehydration that further concentrates glucose in the bloodstream.^[2][11] Hormones such as glucagon, cortisol and adrenaline, which are released in response to stress or illness, worsen the situation by stimulating additional glucose production. This hormonal response explains why DKA can develop rapidly, sometimes within hours, particularly when triggered by infection, missed insulin doses or a new diagnosis of type 1 diabetes.

The information on this page relates to adults. Children and pregnant people can develop DKA at lower thresholds and should follow specialist paediatric or obstetric pathways. Understanding this mechanism is essential for recognising why both glucose and ketone monitoring are central to managing and diagnosing DKA.

How high does blood sugar get in diabetic ketoacidosis?

Blood glucose in DKA is typically above 11 mmol/L and frequently exceeds 20 mmol/L, though euglycaemic DKA can occur with only modestly raised glucose, particularly with SGLT2 inhibitor use.

Blood glucose in DKA is typically above 11 mmol/L, though levels frequently exceed 20 mmol/L and can rise considerably higher without treatment. NHS clinical guidance notes that a blood glucose reading above 11 mmol/L in combination with raised ketones and acidosis is consistent with DKA. However, DKA severity is not determined by glucose level alone: ketone levels and blood pH are equally important diagnostic markers.

In some cases, particularly in people who have eaten little or who are taking sodium-glucose co-transporter 2 (SGLT2) inhibitors, DKA can occur with blood glucose levels that are only modestly elevated, a presentation sometimes called euglycaemic DKA.^[5][6] This makes exclusive reliance on glucose readings potentially misleading.

For context, a normal fasting blood glucose level is generally between 4.0 and 5.9 mmol/L. In the UK, diabetes is diagnosed using fasting plasma glucose of 7.0 mmol/L or above, a two-hour glucose of 11.1 mmol/L or above on an oral glucose tolerance test, or a random plasma glucose of 11.1 mmol/L or above in someone with symptoms of diabetes. Where there are no symptoms, a confirmatory test is required. HbA1c of 48 mmol/mol or above is also used diagnostically in appropriate circumstances, in line with NICE guidance.^[3] In DKA, glucose levels are often several times higher than these thresholds.

People using continuous glucose monitors (CGMs) or blood glucose meters at home may notice rapidly rising readings, which, when accompanied by symptoms such as nausea, vomiting or abdominal pain, should prompt immediate ketone testing and medical assessment.

How is DKA diagnosed using blood glucose and ketone readings?

DKA is diagnosed by blood glucose above 11 mmol/L, blood ketones at or above 3.0 mmol/L, and venous pH below 7.3 or bicarbonate below 15 mmol/L, per JBDS adult guidance.

DKA is diagnosed using a combination of blood glucose, blood or urine ketone measurements, and blood gas analysis to assess acidity. According to NHS and JBDS (Joint British Diabetes Societies) adult DKA guidance, the diagnostic criteria in adults include a blood glucose above 11 mmol/L (or known diabetes), blood ketones of 3.0 mmol/L or above (or urine ketones of 2+ or more on dipstick testing), and a venous bicarbonate below 15 mmol/L or a venous pH below 7.3.

In hospital, blood gas analysis provides the most accurate assessment of acidosis severity. JBDS adult DKA guidance uses the degree of acidosis and clinical features to guide the level of care required rather than applying a simple mild/moderate/severe label based on pH bands alone. Clinicians should refer to the current JBDS adult DKA guideline for the full severity and escalation criteria used in UK practice.

At home, people with diabetes are generally advised to check blood ketones (using a finger-prick ketone meter) whenever blood glucose exceeds 14 mmol/L or when they feel unwell, though individual sick-day plans provided by a diabetes care team should always take precedence. As a general guide based on JBDS and Diabetes UK materials: a blood ketone reading of 0.6 to 1.5 mmol/L warrants increased monitoring and extra insulin as directed by a diabetes care team; readings of 1.5 to 3.0 mmol/L indicate a significant risk of DKA and require urgent contact with a healthcare professional; readings above 3.0 mmol/L require emergency hospital assessment. Urine ketone strips are an alternative but are less accurate and may lag behind blood ketone changes.

Children and pregnant people should follow their specialist team's thresholds, which may differ from those described here.

What treatments bring blood glucose back to a safe level in DKA?

DKA is treated in hospital with IV fluids, a fixed-rate insulin infusion and electrolyte replacement, targeting a ketone reduction of at least 0.5 mmol/L per hour and glucose fall of around 3 mmol/L per hour.

DKA is treated in hospital with intravenous (IV) fluids, insulin infusion and careful electrolyte replacement, all of which work together to lower blood glucose and clear ketones. Rehydration with IV saline is the first priority, as dehydration is almost universal in DKA and contributes to the rise in blood glucose by concentrating it further in the bloodstream.

Once IV fluids are established and potassium levels are confirmed to be adequate (insulin drives potassium into cells and can cause dangerous hypokalaemia if potassium is already low), a fixed-rate IV insulin infusion is started. This suppresses ketone production and allows glucose to enter cells, gradually reducing blood glucose levels. JBDS adult DKA guidance recommends targeting a reduction in blood ketones of at least 0.5 mmol/L per hour, and a fall in blood glucose of approximately 3 mmol/L per hour.

Where a person is already taking long-acting (basal) insulin, JBDS guidance advises that this should be continued at the usual dose during IV insulin treatment. Stopping basal insulin can lead to rebound hyperglycaemia when the infusion is discontinued.

When blood glucose falls to around 14 mmol/L, a glucose infusion is added alongside the insulin to prevent hypoglycaemia while the insulin continues to clear remaining ketones.^[2] Potassium replacement is adjusted throughout based on regular blood tests. The insulin infusion is not stopped until ketones have cleared and the person is able to eat and drink, at which point they transition back to their usual subcutaneous insulin regimen.

Identifying and treating the underlying cause of DKA, such as infection, is an important part of hospital management alongside fluid and insulin treatment.

For people managing diabetes at home, sick day rules provided by a diabetes care team give guidance on adjusting insulin and monitoring during illness to reduce the risk of DKA developing in the first place. These should be discussed with a diabetes care team in advance.

Which warning signs mean you should call 999 straight away?

Call 999 immediately if someone has blood ketones above 3.0 mmol/L with vomiting, loss of consciousness, Kussmaul breathing, or severe drowsiness, as these indicate severe DKA.

Call 999 immediately if someone with diabetes loses consciousness, cannot be roused, is breathing rapidly and deeply (sometimes described as Kussmaul breathing), or is vomiting repeatedly and unable to keep fluids down. These are signs of severe DKA and represent a medical emergency requiring immediate hospital treatment.

Other warning signs that should prompt an urgent call to 999 or attendance at an accident and emergency (A&E) department include:

• Blood ketones above 3.0 mmol/L, particularly if accompanied by vomiting or confusion

• A fruity or pear-drop smell on the breath, caused by acetone produced during ketosis

• Severe abdominal pain, which can mimic a surgical emergency

• Extreme weakness, drowsiness or difficulty staying awake

• Rapid or laboured breathing that is unusual for the person

Do not wait to see if symptoms improve at home if any of these features are present. DKA can deteriorate quickly, and delays in treatment increase the risk of serious complications including cerebral oedema (brain swelling), cardiac arrhythmias due to electrolyte disturbance, and acute kidney injury.^[14]

Children and pregnant people should seek urgent assessment at lower thresholds and should follow the advice of their specialist team.

For symptoms that are concerning but not immediately life-threatening, such as blood ketones between 1.5 and 3.0 mmol/L without vomiting, contact a GP or call NHS 111 for urgent advice. Suspected adverse effects of diabetes medicines, including insulin, can be reported to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk. People with diabetes should ensure their household contacts know how to recognise DKA and when to call for help.

How can people with diabetes reduce their risk of DKA?

The most effective prevention is never stopping insulin without medical advice, following sick day rules, monitoring ketones when glucose exceeds 14 mmol/L, and pausing SGLT2 inhibitors during acute illness as directed.

People with diabetes can significantly reduce their risk of DKA by following consistent insulin management, monitoring blood glucose and ketones regularly, and knowing how to act during illness. The most common preventable cause of DKA is missed or insufficient insulin doses, so never stopping insulin without medical advice, even when unwell and not eating, is a fundamental safety principle.

Key preventive strategies include:

• Following sick day rules provided by a diabetes care team, which include guidance on when to increase monitoring, how to adjust insulin, and when to seek help

• Checking blood glucose more frequently during illness, stress or after surgery

• Testing blood ketones whenever glucose exceeds 14 mmol/L or when feeling unwell, in line with individual sick-day plans

• Staying well hydrated, particularly during illness or hot weather

• Ensuring insulin is stored correctly and has not expired or been damaged by heat or freezing

• Attending regular diabetes reviews to optimise insulin regimens and discuss any concerns

People taking SGLT2 inhibitors should be aware of the risk of euglycaemic DKA. During acute illness, dehydration or before surgical procedures, SGLT2 inhibitors are generally advised to be paused as part of sick day guidance, sometimes referred to by the SADMAN acronym (Sulphonylureas, SGLT2 inhibitors, Diuretics, Metformin, ACE inhibitors and NSAIDs). Advice on when to pause and restart these medicines should be discussed with a diabetes care team in advance, and the MHRA has issued specific Drug Safety Updates on this risk.

For people using insulin pumps, a blocked or disconnected cannula can cause insulin delivery to stop without warning, making ketone monitoring especially important.

Accessing structured diabetes education, such as DAFNE (Dose Adjustment For Normal Eating) for type 1 diabetes, can improve confidence in self-management and reduce the risk of DKA. Online consultations with a registered pharmacy service, such as Bolt Pharmacy, a GPhC-registered UK online pharmacy, may support access to diabetes-related advice and prescriber review as part of a broader care pathway. Ultimately, a well-informed person with diabetes, supported by a knowledgeable care team, is best placed to prevent DKA before it develops.

Scientific References

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2. Diabetic hyperglycaemic emergencies | Treatment summaries.
3. Blood glucose management | Type 2 diabetes in adults (NG28).
4. High blood glucose (hyperglycaemia) in type 1 diabetes (NG18).
5. EMA confirms recommendations to minimise ketoacidosis risk with SGLT2 inhibitors in diabetes.
6. SGLT2 inhibitors: updated advice on the risk of diabetic ketoacidosis.
7. SGLT2 inhibitors: monitor ketones in blood during treatment interruption for surgical procedures or acute serious medical illness.
8. Forxiga 10 mg film-coated tablets.
9. Role of counterregulatory hormones in the catabolic response to stress (Gelfand RA et al.).
10. The controversy concerning counterregulatory hormone secretion (Schade DS et al.).
11. Diabetic ketoacidosis. Endocrinology and Metabolism Clinics of North America (McGarry JD, Foster DW).
12. Improving management of type 1 diabetes in the UK: the Dose Adjustment For Normal Eating (DAFNE) programme as a research test-bed (Heller S et al.).
13. Early subcutaneous basal insulin with intravenous insulin infusion for diabetic ketoacidosis management: A systematic review and meta-analysis of randomised controlled trials. Diabetes, Obesity & Metabolism.
14. Spectrum of complications of severe DKA in children in pediatric Intensive Care Unit. Pakistan Journal of Medical Sciences.

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