Insulin dose and timing

If significant ketonaemia is present (3-hydroxy butyrate is more than 1 mmol/L) this indicates relative hypoinsulinaemia and insulin should be started at time zero.
If significant ketonaemia is not present (3-hydroxy butyrate is less than 1 mmol/L) do NOT start insulin.
Fluid replacement alone with 0.9% sodium chloride solution will result in falling blood glucose and because most patients with HHS are insulin sensitive there is a risk of lowering the osmolality precipitously. Insulin treatment prior to adequate fluid replacement may result in cardiovascular collapse as water moves out of the intravascular space, with a resulting decline in intravascular volume (a consequence of insulin-mediated glucose uptake and a diuresis from urinary glucose excretion)
The recommended insulin dose is a fixed rate intravenous insulin infusion (FRIII) given at 0.05 units per kg per hour (e.g. 4 units/hr in an 80 kg man) is used. A fall of glucose at a rate of up to 5 mmol/L per hour is ideal and once the blood glucose has ceased to fall following initial fluid resuscitation, reassessment of fluid intake and evaluation of renal function must be undertaken. Insulin may be started at this point, or, if already in place, the infusion rate increased by 1 unit/hr. As with DKA, a FRIII (fixed rate intravenous insulin infusion) is) is preferred, though generally lower doses are required.