What is the recommended approach to starting an insulin regimen for a patient newly diagnosed with type 2 diabetes mellitus (T2DM)?

Starting an Insulin Regimen for Newly Diagnosed Type 2 Diabetes

For patients newly diagnosed with type 2 diabetes requiring insulin therapy, start with basal insulin at 10 units per day or 0.1-0.2 units/kg/day, administered once daily at the same time each day, while maintaining metformin therapy if not contraindicated. 1, 2

When to Start Insulin in Type 2 Diabetes

Insulin therapy should be initiated in the following scenarios:

• HbA1c ≥9% at diagnosis 1
• Blood glucose ≥300-350 mg/dL (16.7-19.4 mmol/L) and/or HbA1c ≥10-12% 1
• Presence of significant hyperglycemic symptoms or catabolic features 1
• Failure to achieve glycemic goals with oral antidiabetic medications 1

Initial Insulin Regimen Selection

Basal Insulin Only (Most Common Initial Approach)

• Starting dose: 10 units per day or 0.1-0.2 units/kg/day 1, 2
• Timing: Administer once daily at the same time each day 1
• Insulin options:
  • Long-acting analogs: insulin glargine, insulin detemir, insulin degludec
  • Intermediate-acting: NPH insulin 1
  • Long-acting analogs have modestly less overnight hypoglycemia than NPH 1

Titration of Basal Insulin

• Adjust dose every 3 days based on fasting blood glucose readings 2
• Increase by 2 units if fasting glucose remains above target (80-130 mg/dL) 1, 2
• Decrease by 10-20% if hypoglycemia occurs 2

Combination with Oral Agents

• Maintain metformin when starting insulin therapy (reduces weight gain and insulin requirements) 1, 2
• Consider discontinuing sulfonylureas when more complex insulin regimens are used 1
• Thiazolidinediones or SGLT2 inhibitors may be continued to improve glucose control and reduce total daily insulin dose 1

Monitoring Requirements

• Perform finger-stick blood glucose monitoring before meals and at bedtime until reasonable metabolic control is achieved 1
• Use fasting plasma glucose values to titrate basal insulin 3
• Target fasting glucose: 80-130 mg/dL 1, 4
• Target 2-hour postprandial glucose: <180 mg/dL 4

When to Intensify Beyond Basal Insulin

If basal insulin has been titrated to an acceptable fasting blood glucose level but HbA1c remains above target, consider advancing to combination injectable therapy 1:

1. Add GLP-1 receptor agonist (preferred first step if available) 1

2. Add prandial (mealtime) insulin:

   • Starting dose: 4 units, 0.1 units/kg, or 10% of basal dose at largest meal 1
   • Options include 1-3 injections of rapid-acting insulin (lispro, aspart, or glulisine) before meals 1

3. Switch to premixed insulin twice daily (alternative option):

   • Contains both basal and prandial components (e.g., 70/30 NPH/Regular) 1
   • Less optimal for covering postprandial glucose excursions 1

Patient Education Essentials

• Proper insulin injection technique and site rotation to prevent lipohypertrophy 5
• Self-monitoring of blood glucose 1
• Recognition and treatment of hypoglycemia 1, 2
• "Sick day" rules 1
• Dietary guidance and relationship between food intake and insulin 2

Common Pitfalls to Avoid

1. Overbasalization: Signs include basal dose >0.5 units/kg, high bedtime-morning glucose differential (≥50 mg/dL), or hypoglycemia 1

2. Delayed intensification: Don't delay adding prandial insulin when basal insulin alone fails to achieve target HbA1c 1

3. Abrupt discontinuation of oral medications: This can cause rebound hyperglycemia 3

4. Inadequate monitoring: Insufficient blood glucose monitoring can lead to suboptimal dose adjustments 1

5. Stigmatizing insulin therapy: Avoid describing insulin as a threat, sign of failure, or punishment 1

By following this structured approach to insulin initiation in newly diagnosed type 2 diabetes, you can effectively manage hyperglycemia while minimizing the risks of hypoglycemia and optimizing patient outcomes.