How to treat type 1 diabetes mellitus (T1DM) with subcutaneous (SC) insulin when urine ketones are positive, indicating diabetic ketoacidosis (DKA)?

Treatment of Type 1 Diabetes with Subcutaneous Insulin When Urine Ketones Are Positive

For critically ill or mentally obtunded patients with positive urine ketones indicating DKA, continuous intravenous insulin is the standard of care; however, patients with uncomplicated, mild-to-moderate DKA may be safely treated with subcutaneous rapid-acting insulin analogs in the emergency department or step-down units, which can be safer and more cost-effective than IV insulin. 1

Severity Assessment and Treatment Selection

When IV Insulin is Mandatory

• Critically ill patients with altered mental status, severe dehydration, or hemodynamic instability require continuous IV insulin infusion at 0.1 units/kg/hour 1, 2
• Severe DKA (pH <7.0, bicarbonate <10 mEq/L) necessitates intensive care unit admission with IV insulin 1

When Subcutaneous Insulin is Appropriate

• Mild-to-moderate DKA (pH 7.0-7.3, bicarbonate 10-18 mEq/L, glucose >250 mg/dL) can be treated with subcutaneous rapid-acting insulin analogs 1, 3
• Patient must be alert, cooperative, and able to tolerate oral fluids 1
• Adequate nursing support for frequent bedside glucose monitoring (every 2-4 hours) must be available 1

Subcutaneous Insulin Protocol for Mild-to-Moderate DKA

Initial Dosing

• Give a priming dose of 0.4-0.6 units/kg of rapid-acting insulin: half as IV bolus and half subcutaneously 1
• Follow with 0.1 units/kg/hour subcutaneously of rapid-acting insulin analog (lispro, aspart) 1, 2

Concurrent Management Requirements

• Aggressive fluid resuscitation with isotonic saline at 15-20 mL/kg/hour initially 2, 4
• Potassium replacement of 20-30 mEq/L once serum potassium falls below 5.5 mEq/L and adequate urine output is confirmed 1, 2
• Frequent monitoring: Check blood glucose every 2-4 hours and electrolytes every 2-4 hours 1, 2
• Treat underlying precipitants such as infection, which may have triggered the DKA 1

Glucose Management During Treatment

• When glucose reaches 200-250 mg/dL, add dextrose (5-10%) to IV fluids while continuing insulin 1, 2
• Reduce insulin to 0.05-0.1 units/kg/hour once glucose is controlled, but continue until ketoacidosis resolves 1, 2
• Do not stop insulin based on glucose alone—ketoacidosis takes longer to clear than hyperglycemia 1

Resolution Criteria and Transition

DKA Resolution Parameters

• Glucose <200 mg/dL 2, 5
• Serum bicarbonate ≥18 mEq/L 2, 5
• Venous pH >7.3 2, 5
• Anion gap ≤12 mEq/L 2, 5

Transition to Maintenance Insulin

• Administer basal insulin (glargine or detemir) 2-4 hours BEFORE stopping any insulin therapy to prevent recurrence of ketoacidosis and rebound hyperglycemia 1, 2
• Start a multiple-dose insulin schedule combining rapid-acting and long-acting insulin once the patient can eat 2, 5
• For newly diagnosed type 1 diabetes, initiate approximately 0.5-1.0 units/kg/day as a starting total daily dose 1

Critical Pitfalls to Avoid

Most Common Errors

• Stopping insulin prematurely before complete resolution of ketoacidosis leads to DKA recurrence 2, 4
• Inadequate fluid resuscitation worsens metabolic derangements and delays recovery 4
• Failing to administer basal insulin before stopping treatment insulin—this is the single most common cause of DKA relapse 2
• Using urine ketones alone to monitor treatment response—the nitroprusside method doesn't measure beta-hydroxybutyrate, the predominant ketone, and may falsely suggest worsening ketosis during treatment 1

Safety Considerations

• Subcutaneous insulin carries lower hypoglycemia risk compared to IV protocols (significantly fewer hypoglycemic events documented) 3
• Infection must be identified and treated as it's a common DKA precipitant 1, 2
• Bicarbonate administration is not recommended even for pH <7.0, as it doesn't improve outcomes 1
• Monitor for hypokalemia aggressively—insulin drives potassium intracellularly, and total body potassium is depleted in DKA 1, 2

Special Circumstances

SGLT2 Inhibitor-Associated DKA

• If patient was on SGLT2 inhibitors, discontinue immediately 1, 6
• These agents should be held 3-4 days before any planned procedure 1
• May present as euglycemic DKA (glucose <250 mg/dL) requiring modified protocol with dextrose-containing fluids 7, 6

Discharge Planning

• Ensure structured discharge plan including insulin administration education, glucose monitoring training, and sick-day management 2
• Schedule follow-up within 1-2 weeks to prevent readmission 1
• Provide clear instructions on when to seek emergency care for recurrent symptoms 1