You smartly recall the diagnostic criteria for DKA and realise you just need the third part:

1. Ketonaemia > 3.0mmol/L or significant ketonuria (more than 2+ on standard urine sticks)
2. Blood glucose > 11.0mmol/L or known diabetes mellitus
3. Bicarbonate (HCO3- ) < 15.0mmol/L and/or venous pH < 7.3

You also remember that the difference between venous and arterial pH is 0.02-0.15 pH units. No one cares about that in DKA, so you spare the patient the agony of an ABG. The analyser reads:

pH 7.01

pCO₂ 2.9 kPa

pO₂ 7.6 kPa

HCO₃ 7 mmol/L

Base Excess  -11 mEq/L

Lactate 3.0 mmol/L

Na 131 mmol/L

K 4.1 mmol/L

Glucose 17.2 mmol/L

The patient’s observations are:

Pulse 111, BP 112/66 mmHg, Temp 37.1, RR 24, Sats 100% oa

What is the next step of management?

Normal saline 0.9% @ 1 Litre / 1 hour

Normal saline 0.9%  with 40 mmol KCl @ 1 Litre / 1 hour

Soluble insulin (Actrapid® or Humulin S®) @ 0.1 units/Kg/hr