Hyperosmolar hyperglycaemic state

Question 1

Definition

Answer 1

Life-threatening complication of T2DM characterised by:

• marked hyperglycaemia
• hyperosmolality (due to increased circulating blood glucose)
• no ketosis (insulin present sufficient to supresses lipolysis & hepatic ketogenesis)

Question 2

Aetiology

Answer 2

• AetiologyTypically presents in the elderly with T2DM. Caused by untreated or undiagnosed T2DM or infection/illness- most commonly pneumonia.

Question 3

Pathophysiology

Answer 3

• Reduced insulin levels are sufficient to suppress lipolysis & hepatic ketogenesis BUT are insufficient to inhibit hepatic gluconeogenesis, resulting in marked hyperglycaemia.
• Hyperglycaemia results in osmotic diuresis (glucose is osmotically active so draws water into urine) with associated loss of Na+ & K+.
• Volume depletion (hypovolemia) results in significantly raised serum osmolality (typically > 320mosmol/kg) resulting in hyperviscosity of the blood.

Question 4

Signs and symptoms

Answer 4

• Neurological- confusion, lethargy, hallucinations, headache, reduced consiousness, headaches, papilloedema (swelling of optic disc)→ visual disturbances
• Dehydration & hypovolemia- hypotension, tachycardia, reduced tissue turgor, dry mucous membranes (dry tongue)

& T2DM symptoms (polyuria, polydipsia, polyphagia, fatigue, blurred vision, glycosuria)

Question 5

Investigations

Answer 5

• Marked hyperglycaemia- blood glucose ≥ 30mmol/L & urine dipstick shows heavy glycosuria
• High serum osmolality ≥ 320 mOsmol/kg
• Blood ketones < 3mmol/L (no ketosis- different from DKA)
• ABG- HCO3- >15mmol/L, pH>7.3 (no metabolic acidosis)
• U & E- abnormal electrolytes (usually hypokalemia) due to dehydration & pre-renal AKI (hypovolemia causes reduced renal perfusion, can cause hyperkalemia)
• FBC- leukocytosis may indicate infection as underlying cause (typically pneumonia)

Question 6

Treatment

Answer 6

1st line = Fluid resuscitation with IV 0.9% NaCl- to rehydrate & decrease serum osmolality & decrease blood glucose concentration

1st line = Anticoagulation- VTE prophylaxis with LMWH e.g. SC Dalteparin, Enoxaparin (hyperosmolarity increases coagulability of blood & increases risk of DVT according to Virchow’s triad)

2nd line = add IV insulin infusion (+ K + if hypokalemia)

Question 7

Complications

Answer 7

Increased serum osmolality increases viscosity of blood which predisposes to arterial & venous thrombosis

• DVT leading to pulmonary embolism (hyperosmolaity increases coagulability of blood)
• MI
• Ischaemic stroke
• IV Insulin infusion can cause hypokalemia leading to fatal arrythmias or hypoglycaemia

Question 8

Complications

Answer 8

Increased serum osmolality increases viscosity of blood which predisposes to arterial & venous thrombosis

• DVT leading to pulmonary embolism (hyperosmolaity increases coagulability of blood)
• MI
• Ischaemic stroke
• IV Insulin infusion can cause hypokalemia leading to fatal arrythmias or hypoglycaemia