DKA and HHS — Viva

Q1: Diagnostic criteria (2 min)

"What are the biochemical criteria for DKA?"

• Glucose >11 mmol/L (or known diabetes) ^[1]
• Capillary ketones ≥3 mmol/L (or significant ketonuria)
• Venous pH <7.3 and/or bicarbonate <15 mmol/L
• Clinical context: insulin deficiency ± precipitant

Q2: Potassium paradox (3 min)

"Why can serum potassium be normal or high at presentation yet total body potassium be low?"

• Acidosis and insulin deficiency shift K+ extracellularly
• Total body K+ depleted from urinary losses
• Insulin therapy drives K+ intracellularly → dangerous hypokalaemia
• Rule: JBDS adds 40 mmol/L KCl when K+ is 3.5–5.5 mmol/L, senior review below 3.5; delay insulin until K+ exceeds 3.5 mmol/L (2024 ADA/EASD: replace at 10 mmol/h) ^[2]

Q3: Insulin and fluids (2 min)

"What insulin rate do you use and when do you add dextrose?"

• Fixed-rate IV insulin ~0.1 U/kg/h (local protocol) ^[1]
• When glucose falls to ~14 mmol/L, add 10% dextrose while continuing insulin until ketones/acidosis clear
• Never stop insulin in T1DM without subcutaneous overlap

Q4: Cerebral oedema (2 min)

"Who gets cerebral oedema and what are the warning signs?"

• Especially children/adolescents with DKA
• Headache, bradycardia, hypertension, falling consciousness, posturing, papilloedema ^[3]
• Manage with ABC, hypertonic saline or mannitol per protocol, ICU — prevent by careful fluid/glucose management

Q5: HHS vs DKA (2 min)

"Give three distinctions that change management."

• Osmolality dominant in HHS; ketones/acidosis dominant in DKA ^[4]
• HHS: slower osmolality correction, earlier VTE prophylaxis focus, insulin often later/lower
• DKA: earlier insulin once K+ safe; ketone-driven endpoints

References5ShowHide

1. [1]Dhatariya KK; Joint British Diabetes Societies for Inpatient Care The management of diabetic ketoacidosis in adults: An updated guideline from the Joint British Diabetes Society for Inpatient Care Diabet Med, 2022.PMID 35224769
2. [2]Umpierrez GE, Davis GM, ElSayed NA, et al. Hyperglycemic Crises in Adults With Diabetes: A Consensus Report Diabetes Care, 2024.PMID 39052901
3. [3]Kuppermann N, Ghetti S, Schunk JE, et al. Clinical Trial of Fluid Infusion Rates for Pediatric Diabetic Ketoacidosis N Engl J Med, 2018.PMID 29897851
4. [4]Mustafa OG, Haq M, Dashora U, Castro E, Dhatariya KK; Joint British Diabetes Societies (JBDS) for Inpatient Care Group Management of Hyperosmolar Hyperglycaemic State (HHS) in Adults: An updated guideline from the Joint British Diabetes Societies (JBDS) for Inpatient Care Group Diabet Med, 2023.PMID 36370077
5. [5]Glaser N, Barnett P, McCaslin I, et al. Risk factors for cerebral edema in children with diabetic ketoacidosis N Engl J Med, 2001.PMID 11172153