You are treating a patient with HHS in your emergency department. Her initial glucose on presentation was 50 mmol/L (901 mg/dl). You start her on fluids and then add potassium. After normalization of her potassium, you start her on insulin therapy with 0.1 unit/kg/hr infusion. The patient’s repeat glucose 1 hour later was 49 mmol/L (883 mg/dl). What is the next best management step?