Diabetic Ketoacidosis (Adult)

1. Overview

Diabetic Ketoacidosis (DKA) is a profound metabolic emergency defined by the biochemical triad of Hyperglycaemia, Ketonaemia, and Metabolic Acidosis. It represents the critical failure of glucose homeostasis due to an absolute or relative insulin deficiency combined with a massive surge in counter-regulatory hormones. [1]

The clinical significance of DKA is historical and evolving. It remains the leading cause of mortality in children and young adults with Type 1 Diabetes, primarily due to cerebral oedema. In the 2020s, the rise of Euglycaemic DKA (associated with SGLT2 inhibitors) has redefined the diagnostic threshold, necessitating the measurement of blood ketones even in patients with "normal" glucose levels. [2]

Management is strictly governed by the JBDS (2023) and ADA (2024) protocols, focusing on volume restoration, fixed-rate insulin delivery, and precise electrolyte replacement. Resolution is defined by the clearance of ketones and the restoration of pH, allowing for the critical transition back to subcutaneous insulin. [3]

2. Epidemiology

The T1DM Predominance

• Incidence: 5–8 episodes per 1,000 person-years among patients with Type 1 Diabetes.
• Ketosis-Prone Type 2 (KPD): Increasingly recognized in West African and African American populations (Flatbush Diabetes), where patients present with DKA but can later transition to oral agents. [4]

Mortality Drivers

• Ages less than 20: Cerebral Oedema (0.5–1.0% incidence; 20–25% mortality).
• Ages > 65: Precipitants (MI, Sepsis) and fluid overload/electrolyte failure.

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3. Aetiology & Pathophysiology

⚠️ THE 7-STEP MOLECULAR MECHANISM

1. Insulin Deficiency & Alarmin Surge: Lack of insulin combined with high Glucagon and Catecholamines triggers a profound catabolic switch.
2. Unrestrained Lipolysis: Insulin failure activates Hormone-Sensitive Lipase (HSL) in adipose tissue. Triglycerides are broken down into Free Fatty Acids (FFAs).
3. Carnitine Shuttle Disinhibition: In the liver, the fall in insulin reduces Malonyl-CoA levels. This removes the inhibition of CPT-1 (Carnitine Palmitoyltransferase-1), the "gatekeeper" of the mitochondria.
4. HMG-CoA Pathway Activation: FFAs enter the mitochondria and undergo β-oxidation to Acetyl-CoA. Excess Acetyl-CoA is diverted into the HMG-CoA cycle by HMG-CoA Synthase (the rate-limiting enzyme).
5. Ketogenesis: Two primary ketone bodies are produced: Acetoacetate (AcAc) and 3-β-hydroxybutyrate (3HB). 3HB is the dominant ketone in DKA (ratio often 10:1 vs AcAc).
6. Anion Gap Acidosis: 3HB and AcAc are strong acids (pKa ~4.8). They dissociate, releasing protons (H+) that consume bicarbonate (HCO3-). This creates a High Anion Gap Metabolic Acidosis (HAGMA).
7. Osmotic Diuresis & Collapse: Severe hyperglycaemia exceeds the renal threshold (10 mmol/L), causing an osmotic pull that strips the body of water, sodium, and potassium (Total water deficit: 100 mL/kg). [5, 6, 7]

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4. Clinical Presentation

Symptoms

• GI Distress: Diffuse abdominal pain, nausea, and persistent vomiting. (Pain can mimic a "Surgical Abdomen").
• Respiratory: "Air hunger" (Kussmaul breathing).
• Neurological: Drowsiness and confusion (correlation with hyperosmolality).

Physical Signs

1. Kussmaul Respirations: Deep, rapid, sighing breaths to blow off CO2 (compensatory respiratory alkalosis).
2. Ketotic Breath: "Pear drops" or "Fruity" smell (due to Acetone, a breakdown product of AcAc).
3. Severe Dehydration: Sunken eyes, reduced skin turgor, and dry mucous membranes.
4. Hypothermia: Common due to peripheral vasodilation; fever suggests sepsis as a precipitant. [8]

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5. Investigations

The Diagnostic Triad (JBDS)

1. Hyperglycaemia: Glucose > 11.0 mmol/L (or known Diabetes).
2. Ketonaemia: Blood Ketones ≥3.0 mmol/L. (Urine ketones are less reliable).
3. Acidosis: Venous pH less than 7.30 or Bicarbonate less than 15.0 mmol/L.

The SGLT2i Trap: Euglycaemic DKA

Patients on Gliflozins (SGLT2i) may present with a pH of 7.1 and ketones of 5.0, but a blood glucose of only 6.5 mmol/L. This occurs because SGLT2i promote renal glucose excretion, masking the hyperglycaemia. Always check ketones in a sick SGLT2i user. [9]

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6. Management: The 2024 Protocol

1. Fluid Resuscitation (Volume First)

• Immediate: 1L 0.9% NaCl over 1 hour.
• Subsequent: 1L over 2h, then 2h, then 4h, then 4h.
• Switch to 10% Dextrose: When CBG falls below 14 mmol/L. Do not stop the insulin!

2. Fixed-Rate Insulin (FRII)

• Dose: 0.1 units/kg/hr. (e.g. 7 units/hr for a 70kg patient).
• Action: Suppresses hepatic ketogenesis. Continue until ketones less than 0.6 and pH > 7.3.

3. Potassium Replacement (The Killer)

• Rule: Initial serum K+ is falsely high due to acidosis. Once insulin starts, K+ will plummet.
• Protocol: Add 40 mmol/L KCl to every bag if K+ is 3.5–5.5 mmol/L.
• Red Alert: If K+ less than 3.5, hold insulin and replace K+ urgently. [10]

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7. Evidence: Landmark Trials

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8. Single Best Answer (SBA) Questions

Question 1

A 22-year-old female with T1DM is admitted with DKA. pH 7.15, Ketones 5.2, Glucose 22. K+ is 3.1 mmol/L. What is the most appropriate immediate action?

• A) Start IV Insulin at 0.1 u/kg/hr
• B) Give 1L 0.9% NaCl with 40 mmol KCl over 1 hour
• C) Give 1L 0.9% NaCl and HOLD insulin until K+ > 3.5
• D) Give IV Bicarbonate 8.4%
• E) Loading dose of 10 units SC insulin
• Answer: C. Starting insulin when K+ is low (less than 3.5) will drive potassium into cells, potentially causing fatal cardiac arrest. Volume resuscitation and K+ replacement are the priority until K+ is at a safe level to start insulin.

Question 2

Which molecule acts as the "gatekeeper" to the mitochondria, and whose depletion in DKA allows for the massive entry of free fatty acids for ketogenesis?

• A) HMG-CoA
• B) Malonyl-CoA
• C) Acetoacetate
• D) Pyruvate
• E) Citrate
• Answer: B. Insulin promotes Malonyl-CoA, which inhibits CPT-1. In DKA, the lack of insulin causes Malonyl-CoA to fall, "opening the gates" for FFAs into the mitochondria.

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9. Viva Scenario: The "Normal Sugar" DKA

Examiner: "A patient with Type 2 Diabetes on Dapagliflozin presents with nausea and a pH of 7.2. Their blood sugar is 8.0 mmol/L. Is this DKA?"

Candidate:

1. Suspicion: Yes, I highly suspect Euglycaemic DKA.
2. Mechanism: SGLT2 inhibitors cause the kidneys to dump glucose into the urine, which can keep blood sugar low even during a profound ketoacidotic state.
3. Diagnosis: I would immediately check blood ketones. If they are ≥3.0 mmol/L, the diagnosis is confirmed regardless of the "normal" sugar.
4. Management: I would treat with the full DKA protocol, but I would need to start 10% Dextrose immediately to allow for the insulin infusion required to clear the ketones.

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10. Patient Explanation

"DKA is a serious complication where your body runs out of its main fuel (sugar) and starts to burn fat too quickly for energy. This creates 'acid waste' called ketones that poison the blood. It feels like you are gasping for air because your body is trying to breathe out the acid. We are giving you a constant 'drip' of insulin to stop the fat burning, and lots of fluids to flush out the acid. We will be checking your finger-prick tests every hour until the acid is gone."

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11. References

1. Joint British Diabetes Societies (JBDS-IP). Management of Diabetic Ketoacidosis in Adults. 2023. Online
2. American Diabetes Association (ADA). Standards of Care in Diabetes—2024. Diabetes Care. 2024. [DOI: 10.2337/dc24-S016]
3. Dhatariya KK, et al. Diabetic Ketoacidosis in Adults. BMJ. 2020. [PMID: 33115745]
4. Dhatariya KK. Euglycaemic diabetic ketoacidosis: a review. Curr Opin Endocrinol Diabetes Obes. 2024.
5. Kitabchi AE, et al. Hyperglycemic crises in adult patients with diabetes. Diabetes Care. 2009. [PMID: 19564476]

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Last Updated: 2026-01-05 | MedVellum Editorial Team