PassFinals
Endocrinology & Metabolic

Diabetic Ketoacidosis

Insulin deficiency lets the liver overproduce glucose and acidic ketone bodies at once, giving hyperglycaemia, ketonaemia and a high-anion-gap metabolic acidosis on top of profound osmotic dehydration.

In a nutshell

DKA is insulin deficiency producing hyperglycaemia, ketonaemia and metabolic acidosis, usually in type 1 diabetes. Give 0.9% sodium chloride 1 L IV over the first hour, then fixed-rate soluble insulin at 0.1 units/kg/hour.

Classic presentation

A young adult with type 1 diabetes, two days of vomiting and abdominal pain after missed insulin, now dehydrated with Kussmaul (deep sighing) breathing and pear-drop breath.

Key points

  • Fixed-rate means a set weight-based rate regardless of glucose. A variable-rate infusion (VRIII) is titrated to glucose and is the wrong tool in DKA.
  • Euglycaemic DKA is ketoacidosis with normal or near-normal glucose, classically on a sodium-glucose co-transporter 2 (SGLT2) inhibitor or in pregnancy. Treatment is identical.
  • The anion gap is (sodium plus potassium) minus (chloride plus bicarbonate). Above 16 means severe DKA.
  • About a third of adult episodes occur in type 2 diabetes; treatment is unchanged. Recurrent DKA often has a psychological or social driver.
  • Do not give bicarbonate or phosphate routinely: fluids and insulin correct the acidosis, and bicarbonate can worsen cerebrospinal fluid acidosis.
  • UK mortality is under 1%. Adult deaths follow severe hypokalaemia, respiratory distress syndrome and the precipitant; cerebral oedema dominates in children.

First-line investigation

Capillary glucose, blood ketones and a venous gas together: glucose above 11 mmol/L (or known diabetes), ketones above 3 mmol/L, pH below 7.3 and/or bicarbonate below 15 mmol/L.

Management

Resuscitate, then fluids, then insulin

  • Monitored bed, two large-bore cannulae, ABCDE (airway, breathing, circulation, disability, exposure). Send venous gas, U&E, glucose, ketones, FBC, cultures and ECG.1,2
  • Systolic BP below 90 mmHg: 0.9% sodium chloride 500 mL over 10 to 15 minutes, repeat if still hypotensive. Most need 500 to 1000 mL rapidly.1
  • Otherwise 0.9% sodium chloride 1 L over the first hour, then 1 L each over 2, 2, 4, 4 and 6 hours. Reassess the circulation at 12 hours.1,2
  • Then soluble insulin 0.1 units/kg/hour: 50 units made up to 50 mL with 0.9% sodium chloride, so 7 mL/hour at 70 kg. Continue usual long-acting insulin. No priming bolus.1,2

Clear the ketones, protect the potassium

  • Potassium above 5.5 mmol/L: none in the bag. 3.5 to 5.5 mmol/L and passing urine: 40 mmol/L. Below 3.5 mmol/L: senior review, more is needed.1,2
  • Glucose below 14 mmol/L: add 10% glucose at 125 mL/hour alongside the saline and consider reducing insulin to 0.05 units/kg/hour. Do not stop the insulin.1
  • Repeat glucose and ketones every hour, and the venous gas at 60 minutes, 2 hours, then every 2 hours. Target a ketone fall of at least 0.5 mmol/L/hour.1
  • If ketones stall, check the pump, line and syringe first, then increase insulin by 1 unit/hour each hour until they fall at target.1

Severe DKA and deterioration

  • Severe DKA: ketones above 6 mmol/L, bicarbonate below 5 mmol/L, pH below 7.0, potassium below 3.5 mmol/L, GCS below 12. Also saturations below 92%, systolic BP below 90 mmHg, anion gap above 16.1
  • Pulse above 100 or below 60 also counts. Any criterion means consultant review, continuous cardiac monitoring and level 2 (high dependency) care.1
  • Treat the precipitant. Assess VTE and bleeding risk; give prophylactic low molecular weight heparin (LMWH) for at least 7 days only when VTE risk outweighs bleeding risk. Nasogastric tube if obtunded or vomiting; urgent brain imaging if GCS falls.1,2,4
  • Normal glucose does not exclude DKA. Stop any SGLT2 inhibitor immediately and report it on a Yellow Card, the UK scheme for suspected adverse drug reactions.1,3

Resolution and discharge

  • Resolution is blood ketones below 0.6 mmol/L and venous pH above 7.3. Ignore bicarbonate here: saline-induced hyperchloraemic acidosis holds it down.1
  • When eating again, give the subcutaneous rapid-acting dose at a meal, then stop the infusion 30 to 60 minutes afterwards. Newly diagnosed: basal insulin 0.25 units/kg daily.1
  • Diabetes team review within 24 hours, sick-day rules, a home ketone meter, and specialist review before discharge if newly diagnosed. Use your trust's DKA prescription chart throughout.1

Exam traps

  • Fluids before insulin: insulin into an underfilled circulation drops the blood pressure and the potassium.
  • A normal or high potassium on arrival is not reassurance: it falls fast once insulin starts.
  • A normal glucose does not exclude DKA. Check ketones and pH, especially on an SGLT2 inhibitor.
  • Do not stop insulin when glucose normalises. Ketogenesis is still running, and ketones define resolution.
  • Abdominal pain and vomiting in DKA mimic a surgical abdomen and settle as the acidosis corrects.
  • Urine ketones stay positive after DKA has resolved, so they can never be the endpoint.

Illustrations

Insulin deficiency driving DKADiagram showing absolute insulin deficiency simultaneously permitting unrestrained hepatic glucose output and unopposed lipolysis with hepatic ketogenesis.PassFinals · original
Kussmaul breathing and clinical signsIllustration of the deep, sighing respiratory pattern, dehydration and acetone breath odour seen in diabetic ketoacidosis.PassFinals · original
Fluid, insulin and potassium treatment timelineChart showing the sequence and interaction of intravenous fluids, fixed-rate insulin infusion and potassium replacement over the first 24 hours.PassFinals · original

Key sources

  1. Joint British Diabetes Societies for Inpatient Care (JBDS-IP), The Management of Diabetic Ketoacidosis in Adults, revised March 2023 (JBDS 02)
  2. NICE, Type 1 diabetes in adults: diagnosis and management (NG17)Published 26 Aug 2015 | Updated 17 Aug 2022
  3. Medicines and Healthcare products Regulatory Agency (MHRA), SGLT2 inhibitors: updated advice on the risk of diabetic ketoacidosis (Drug Safety Update)Published 18 Apr 2016
  4. NICE, Venous thromboembolism in over 16s: reducing the risk of hospital-acquired deep vein thrombosis or pulmonary embolism (NG89)Published 21 Mar 2018 | Updated 13 Aug 2019

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.