What is the most appropriate next step in management?

A 26-year-old woman was recovering from diabetic ketoacidosis and had been switched to her usual basal bolus insulin regimen. Her capillary blood glucose measurements during the day were high but fasting plasma glucose was in the range 5.0C7.0 mmol/L (3.0C6.0). She was drinking and eating normally.

On examination, her pulse was 76 beats per minute and her blood pressure was 106/66 mmHg. Urinalysis showed ketones 1+.

Investigations:

serum sodium143 mmol/L (137C144)

serum potassium4.4 mmol/L (3.5C4.9)

serum bicarbonate22 mmol/L (20C28)

serum creatinine72 µmol/L (60C110)

plasma glucose 2 h after breakfast21 mmol/L

What is the most appropriate next step in management?
A . change to twice daily pre-mixed insulin
B . increase basal insulin at bed time
C . increase bolus insulin with meal
D . start glucose 5% with intravenous insulin
E . start variable-rate intravenous insulin infusion