When do you initiate insulin in a patient with type 2 diabetes?

Insulin Initiation in Type 2 Diabetes

Insulin therapy should be initiated in patients with type 2 diabetes who are not achieving glycemic goals with lifestyle intervention and oral hypoglycemic agents as soon as possible, ideally within 3 months of recognizing treatment failure. 1, 2

Primary Indications for Insulin Initiation

• Initiate insulin immediately in patients with:

  • HbA1c > 9.0% or FPG ≥ 11.1 mmol/L (≥200 mg/dL) 1, 2
  • Marked hyperglycemia (blood glucose ≥250 mg/dL) with symptoms (polyuria, polydipsia, nocturia, weight loss) 1, 2
  • Ketosis or diabetic ketoacidosis 1
  • Failure to achieve glycemic targets after 3 months of optimized oral medication therapy 1, 2

• Short-term intensive insulin therapy (2 weeks to 3 months) should be considered for newly diagnosed patients with severe hyperglycemia (HbA1c > 9.0%) 1, 2, 3

Insulin Regimen Selection

Initial Insulin Regimen

• Start with basal insulin (long-acting) as the most convenient initial regimen 1, 2

  • Starting dose: 10 U or 0.1-0.2 U/kg/day 1, 4
  • Administer subcutaneously once daily at any time of day, but at the same time every day 4
  • Continue metformin when initiating insulin 1

• For patients with severe hyperglycemia (blood glucose ≥250 mg/dL, HbA1c ≥8.5%):

  • Start with basal insulin while initiating and titrating metformin 1, 2
  • In cases of ketosis/ketoacidosis, use subcutaneous or intravenous insulin to rapidly correct hyperglycemia and metabolic derangement 1

Insulin Intensification

• If basal insulin has been titrated to an acceptable fasting blood glucose but HbA1c remains above target, advance to combination injectable therapy 1

• Options include:

  • Adding a GLP-1 receptor agonist 1
  • Adding mealtime insulin (one to three injections of rapid-acting insulin analog) 1
  • Switching to twice-daily premixed insulin 1

• For patients treated with basal insulin who don't meet glycemic targets, move to multiple daily injections with basal and premeal bolus insulins 1

Monitoring and Dose Adjustment

• Monitor HbA1c every 3 months 1

• Self-monitoring of blood glucose is recommended for patients:

  • Taking insulin or medications with risk of hypoglycemia 1
  • Initiating or changing diabetes treatment regimen 1
  • Not meeting treatment goals 1

• Titrate insulin doses every 3-4 days until target blood glucose levels are reached 5

  • Fasting and premeal blood glucose goal: 80-130 mg/dL 5
  • Two-hour postprandial goal: <180 mg/dL 5

Special Considerations

• In patients initially treated with insulin and metformin who achieve glucose targets, insulin can be tapered over 2-6 weeks by decreasing the dose 10-30% every few days 1, 3

• Short-term intensive insulin therapy in newly diagnosed patients can:

  • Quickly normalize glycemic control 3
  • Improve β-cell function 3
  • Potentially lead to remission in some patients 3

• For patients with severe insulin resistance, U-500 insulin may be a more effective alternative to U-100 insulin 6

Common Pitfalls and Caveats

• Insulin initiation is often delayed too long, leading to prolonged hyperglycemia and increased risk of complications 7
• Weight gain and hypoglycemia are common adverse effects of insulin therapy 6, 5
  • Minimize these effects by using basal insulins in combination with metformin, incretin mimetics, or DPP-4 inhibitors 6
• Insulin analogues have lower risk of hypoglycemia compared to human insulin but at significantly higher cost 5
• Patients with one or more episodes of severe hypoglycemia may benefit from temporary relaxation of glycemic targets 5
• Rotate injection sites to reduce risk of lipodystrophy and localized cutaneous amyloidosis 4

By following these guidelines for insulin initiation and intensification, clinicians can help patients with type 2 diabetes achieve better glycemic control and reduce the risk of diabetes-related complications.