What is the recommended initial approach to insulin therapy for patients requiring it?

Insulin Therapy: Initial Approach

For patients with type 2 diabetes requiring insulin, start with basal insulin at 10 units daily or 0.1-0.2 units/kg body weight, administered subcutaneously once daily at the same time each day, typically continued alongside metformin. 1

When to Initiate Insulin

Immediate insulin initiation is mandatory when:

• Blood glucose ≥300-350 mg/dL (16.7-19.4 mmol/L) and/or HbA1c ≥10-12%, especially with symptoms or catabolic features (weight loss, ketosis) 1
• In these severe cases, use basal insulin plus one mealtime insulin injection as the preferred initial regimen 1

Consider starting insulin when:

• HbA1c ≥9% despite oral agents 1
• Patients fail to achieve glycemic goals on oral antidiabetic drugs 1

Specific Basal Insulin Regimen

Starting dose: 1, 2

• 10 units once daily (simplest approach for most patients)
• OR 0.1-0.2 units/kg/day based on degree of hyperglycemia
• For type 2 diabetes specifically: 0.2 units/kg or up to 10 units once daily 2

Preferred basal insulin options: 1

• NPH insulin
• Insulin glargine (U-100)
• Insulin detemir
• Insulin degludec

Administration details: 2

• Inject subcutaneously into abdomen, thigh, or deltoid
• Same time every day (any time, but consistent)
• Rotate injection sites within same region
• Do NOT dilute or mix with other insulins
• Do NOT administer intravenously or via pump

Titration Strategy

Increase basal insulin dose by: 1, 3

• 1 unit per day (for NPH, detemir, glargine 100 units/mL), OR
• 2-4 units once or twice weekly

Target fasting plasma glucose: 1

• 80-130 mg/dL (individualized based on patient factors)
• Continue titration until fasting glucose consistently within target

Patient self-titration algorithms improve glycemic control and should be provided 1

Concomitant Medications

Continue metformin when starting basal insulin 1

May continue one additional non-insulin agent 1

Discontinue sulfonylureas when starting insulin to reduce hypoglycemia risk 1

Advancing Beyond Basal Insulin

If HbA1c remains above target despite optimized fasting glucose on basal insulin: 1

Add ONE of the following:

• GLP-1 receptor agonist (preferred for weight considerations) 1
• Single prandial insulin injection before the largest meal (rapid-acting analog: lispro, aspart, or glulisine) 1
  • Starting dose: 4 units per meal, 0.1 units/kg per meal, or 10% of basal dose 1
  • Administer immediately before eating 1

Avoid premixed insulins as initial therapy - they have suboptimal pharmacodynamic profiles for postprandial coverage and require fixed meal schedules 1

Type 1 Diabetes Distinction

For type 1 diabetes, the approach differs significantly: 1, 2

• Starting dose: approximately one-third of total daily insulin requirements as basal insulin 2
• Must use concomitant short-acting prandial insulin for remaining two-thirds 1, 2
• Total starting dose typically 0.4-1.0 units/kg/day (higher during puberty) 1

Critical Safety Considerations

Monitor blood glucose more frequently during insulin initiation and any regimen changes 1, 2

Hypoglycemia risk increases when switching between insulin formulations: 2

• From glargine 300 units/mL to glargine 100 units/mL: start at 80% of previous dose
• From twice-daily NPH to once-daily basal analog: start at 80% of total NPH dose
• From once-daily NPH to basal analog: use same dose

Never share insulin pens, syringes, or needles between patients - risk of blood-borne pathogen transmission 2

Comprehensive patient education is mandatory: 1

• Self-monitoring of blood glucose technique
• Insulin injection technique and site rotation
• Hypoglycemia recognition and treatment
• "Sick day" management rules