Insulin Dosing for Type 2 Diabetes with DKA and Infected Foot Ulcer

Immediate DKA Management

The American Diabetes Association recommends immediate IV insulin infusion at 0.1 units/kg/hour to resolve DKA before transitioning to subcutaneous Lantus 1, 2
Start continuous IV regular insulin at 0.1 units/kg/hour, which is approximately 7-8 units/hour for a 77 kg patient 3, 2
Monitor blood glucose every 1-2 hours, expecting glucose to fall 50-75 mg/dL per hour 2
When glucose reaches 250 mg/dL, reduce IV insulin to 0.05-0.1 units/kg/hour and add dextrose to IV fluids 2
Continue IV insulin until DKA resolves, defined as glucose <200 mg/dL, bicarbonate ≥18 mEq/L, pH >7.3, and anion gap ≤12 mEq/L 2, 4

Check potassium before starting insulin, and delay insulin if K+ <3.3 mEq/L to prevent fatal arrhythmias 4
Add 20-30 mEq potassium per liter IV fluid once K+ is 3.3-5.5 mEq/L and urine output is adequate 3, 4
Target serum potassium 4-5 mEq/L throughout treatment 4

Administer the first dose of subcutaneous Lantus 2-4 hours before stopping the IV insulin infusion to prevent rebound hyperglycemia and recurrent DKA 1, 4
Start Lantus at 40-50 units once daily, which is approximately 0.5-0.65 units/kg for a 77 kg patient 5

Start with a 1:10 carbohydrate ratio using rapid-acting insulin before each meal 5
Use 1 unit of rapid-acting insulin to lower blood glucose by 50 mg/dL, with a target glucose of 100-150 mg/dL 5
Calculate the correction dose using the formula: (Current glucose - Target glucose) ÷ 50 5

Discontinue SGLT2 inhibitors immediately, as they should have been stopped 3-4 days before any acute illness to prevent DKA 1, 4
Hold metformin during acute illness and restart once stable and eating normally 1
Do not restart SGLT2 inhibitors until the infection is resolved and the patient is metabolically stable 1

Never stop IV insulin before administering subcutaneous basal insulin, as this causes rebound hyperglycemia and recurrent DKA 1, 4
Never use correction-only insulin without basal coverage, as this approach leads to worse outcomes and higher complication rates 1
Never restart SGLT2 inhibitors during acute illness or infection, as this increases the risk of recurrent DKA 1, 4

The American Diabetes Association recommends ensuring stable glucose measurements for at least 4-6 hours consecutively, hemodynamic stability, patient ability to eat or has a stable nutrition plan, before transitioning to subcutaneous insulin 6

The American College of Endocrinology suggests basing the total daily dose on the average IV insulin infusion rate from the 12 hours prior to transition, with total daily dose = Average hourly IV insulin rate × 24 hours 6
The Endocrine Society recommends dividing the total daily dose into 50% as basal insulin (long-acting: glargine or detemir) given once daily, and 50% as prandial insulin (rapid-acting: lispro, aspart, or glulisine) divided equally before three meals 6, 7, 8

The American Association of Clinical Endocrinologists advises against using sliding scale (correction-only) insulin alone, as this approach leads to worse outcomes and higher complication rates in patients with known diabetes 6
The European Association for the Study of Diabetes recommends monitoring potassium closely as hypoglycemia risk remains elevated during the first 24-48 hours 6

The American Diabetes Association recommends a total daily insulin dose of 0.5 units/kg/day for metabolically stable patients after resolution of ketoacidosis, with 50% of this dose given as basal insulin (such as glargine or detemir) administered once daily 9, 10
For patients requiring higher doses, such as those in metabolic stress or with infection, doses up to 0.65-1.0 units/kg/day may be necessary 9, 10

Before transitioning from intravenous to subcutaneous insulin, confirm that all of the following criteria are met: blood glucose < 200 mg/dL, serum bicarbonate ≥ 18 mEq/L, venous pH > 7.3, and anion gap ≤ 12 mEq/L 11

An alternative method for calculating the total daily dose is based on the average intravenous insulin infusion rate over the last 12 hours multiplied by 24 hours, with 50% of this dose given as basal insulin 12
The French guidelines for perioperative management recommend administering 1/2 of the 24-hour intravenous insulin dose as long-acting subcutaneous insulin once in the evening 12