Endocrinology
Hyperglycaemia in an unwell adult
High capillary glucose in an acutely unwell patient with or without known diabetes
Time-critical presentation5-stage reasoningCase walk-through
What to ask
Decide immediately whether this is ketoacidosis, a hyperosmolar state or stress hyperglycaemia.- Duration of polyuria, polydipsia, weight loss, vomiting and abdominal pain.
- Insulin or oral agent omission, pump failure, missed basal dose.
- Precipitants: infection, chest pain, steroids, alcohol, pregnancy, new drugs, surgery, fasting.
- SGLT2 inhibitor use — glucose may be near normal in ketoacidosis.
- Previous DKA episodes, psychosocial context and access to supplies.
Discriminators
- Ketones decide the diagnosis, not the glucose value.
- Days of gradual decline with profound dehydration and minimal ketones suggests a hyperosmolar state.
- Vomiting plus abdominal pain in a diabetic patient is DKA until measured otherwise.
Case walk-through — Ketones 5.8, potassium 3.1
4 decisions · hardCase vignette
A 19-year-old with type 1 diabetes has vomited all day after running out of insulin. Glucose 32 mmol/L, capillary ketones 5.8 mmol/L, venous pH 7.05, bicarbonate 6 mmol/L, potassium 3.1 mmol/L, pulse 122/min, blood pressure 96/58 mmHg. He weighs 60 kg and has had 1 L of 0.9% sodium chloride.
- 1
Potassium is 3.1 mmol/L. What happens next?
- 2
He weighs 60 kg. What is the fixed-rate insulin infusion rate?
Answer the previous step to continue.
- 3
Four hours later glucose is 12.5 mmol/L and ketones are 3.4 mmol/L. What do you change?
Answer the previous step to continue.
- 4
Ketones are 0.4 mmol/L, pH 7.34, bicarbonate 19 mmol/L and he is eating. How do you convert?
Answer the previous step to continue.
Full checklist
Original structured checklist- 1
History
- Duration of symptoms, insulin or oral agent omission, pump problems
- Precipitants: infection, chest pain, steroids, alcohol, pregnancy, new drugs
- SGLT2 inhibitor use — the glucose may be near-normal in DKA
- Previous DKA episodes and psychosocial context
- 2
Examination
- Hydration, blood pressure, heart rate, mental state
- Kussmaul respiration and ketotic breath
- Full source search including feet, skin and chest
- Abdominal examination — pain may be metabolic rather than surgical
- 3
Initial tests
- Capillary glucose and capillary beta-hydroxybutyrate in every unwell diabetic patient
- Venous blood gas, urea and electrolytes, FBC, ECG
- Anion gap, corrected sodium and calculated osmolality
- Precipitant screen: cultures, chest radiograph, troponin, pregnancy test
- 4
Differential
- Diabetic ketoacidosis, including euglycaemic DKA
- Hyperosmolar hyperglycaemic state
- Stress hyperglycaemia in critical illness or steroid therapy
- Newly diagnosed diabetes without acidosis
- 5
Immediate treatment
- DKA: 0.9% sodium chloride 1 L in the first hour, fixed-rate insulin 0.1 units/kg/h, potassium 40 mmol/L when 3.5-5.5
- Add 10% glucose alongside saline once glucose falls below 14 mmol/L and continue insulin until ketones clear
- Continue usual long-acting basal insulin throughout
- HHS: slower fluid replacement with insulin used cautiously and osmolality change limited
- Treat the precipitant and withhold metformin and SGLT2 inhibitors during the acute illness
- 6
Follow-up
- Convert to subcutaneous insulin only after resolution with an overlap
- Diabetes specialist team review before discharge in every case
- Structured sick-day education and a written personalised plan
- Early outpatient review and address recurrent presentations
Related diseases
Demo content. Educational decision support only. Verify every dose, citation and recommendation against your national formulary and the primary source before clinical use.