Author(s): Vimal Venugopal , Vito Carone , Manohara Kenchaiah
Consider hyperosmolar hyperglycaemic state (HHS) in any ill patient with diabetes, especially if volume depletion and drowsiness are prominent.
- HHS typically occurs in patients with type 2 diabetes, but can also occur in type 1 diabetes. Any illness that leads to a reduced fluid intake can precipitate HHS, which may be the first presentation of diabetes.
- The onset of HHS is usually over a number of days, and slower compared to DKA. However, an overlap syndrome with features of both HHS and DKA may be seen.
- Mortality of patients with HHS is high (up to 50%), with the major causes of death being the precipitating illness, thromboembolism and aspiration pneumonia.
Hyperosmolar hyperglycaemic state is differentiated from diabetic ketoacidosis (Chapter 83) by:Hyperosmolar hyperglycaemic state is differentiated from diabetic ketoacidosis (Chapter 83) by:- Blood glucose >30 mmol/L, but no ketoacidosis (plasma ketones <3 mmol/L, venous bicarbonate >15 mmol/L) and
- Plasma osmolality >350mOsmol/kg (normal range 285–295mOsmol/kg); this can be measured directly or calculated from the formula: plasma osmolality = [2 (plasma Na)+glucose+urea].
Management
Clinical assessment, investigation and management are as for DKA (Chapter 83), with the differences noted below. Identify and treat any precipitating illness.
- Use normal saline to correct the fluid deficit. Switch to 0.45% sodium chloride solution if plasma osmolality is not falling despite adequate fluid replacement. Plasma sodium may rise initially but this is not an indication to use 0.45% sodium chloride solution.
- The rate of fall of plasma sodium should not exceed 10 mmol/L in 24h.
- The fall in blood glucose should be no more than 5 mmol/L/h. Low dose IV insulin (0.05units/kg/h) should only be administered if there is significant ketonaemia/ketonuria (plasma ketones >1 mmol/L or urine ketones greater than 2+), or if blood glucose is not falling despite correction of the fluid deficit.
- Aim for a positive fluid balance of 3–6L by 12h and the remaining replacement of estimated fluid losses within next 12h (average deficit in HHS is 10L). Encourage the patient to drink when conscious level allows safe swallowing.
- The risk of foot ulceration is high, particularly if the patient has a reduced conscious level. The heels should be protected and the feet checked daily.
- The risk of thromboembolism is high. Unless contraindicated (e.g. recent stroke), give full-dose low-molecular-weight heparin or unfractionated heparin by IV infusion (Chapter 103) until mobile.
Continue insulin unless the total daily requirement falls below 20 units, when an oral hypoglycaemic can be tried. Most patients can subsequently be maintained on oral hypoglycaemic therapy (or even managed by diet alone), although recovery of endogenous insulin production may be delayed. Ask advice from the diabetes team on an appropriate regimen before discharge.