How to initiate insulin therapy?

Initiating Insulin Therapy in Diabetes Management

The most appropriate way to initiate insulin therapy is to start with basal insulin at 0.1-0.2 units/kg/day or 10 units once daily, titrating the dose by 2 units every 3 days until reaching the fasting plasma glucose target without hypoglycemia. 1, 2, 3

Initial Assessment and Decision-Making

• Insulin therapy should be initiated when A1C ≥9% or blood glucose levels ≥300 mg/dL, and especially when A1C is 10-12% with symptomatic hyperglycemia 2
• For patients with type 2 diabetes, basal insulin alone is typically the most convenient initial regimen and can be added to metformin and other oral agents 1, 2
• For patients with type 1 diabetes, multiple daily injections (MDI) or continuous subcutaneous insulin infusion (CSII) should be initiated at diagnosis 2
• Consider insulin as first injectable if evidence of ongoing catabolism, symptoms of hyperglycemia are present, when A1C levels >10% or blood glucose levels >300 mg/dL, or when type 1 diabetes is a possibility 1

Selecting the Initial Insulin Regimen

For Type 2 Diabetes:

• Start basal insulin at 10 units per day or 0.1-0.2 units/kg/day, depending on the degree of hyperglycemia 1, 3
• Continue metformin when initiating insulin therapy, as it is the preferred first-line agent 2, 4
• If using sulfonylureas, consider discontinuing them once insulin is started to reduce hypoglycemia risk 1
• If affordable, basal insulin analogue formulations (glargine, detemir, degludec) are preferred to NPH insulin because of their reduced risk of hypoglycemia, particularly nocturnal hypoglycemia 1, 5, 6

For Type 1 Diabetes:

• The recommended starting dosage is approximately one-third of the total daily insulin requirements as basal insulin 3
• Use short-acting, premeal insulin to satisfy the remainder of the daily insulin requirements 3

Dose Titration Protocol

• Set a fasting plasma glucose (FPG) target (typically 80-130 mg/dL) 1, 4
• Increase basal insulin dose by 2 units every 3 days to reach FPG target without hypoglycemia 1, 2, 7
• If hypoglycemia occurs, determine the cause; if no clear reason, lower the dose by 10-20% 1, 4
• Patient self-titration algorithms have shown greater reductions in A1C compared to clinic-managed titration in some studies 7

When to Intensify Insulin Therapy

• Assess adequacy of basal insulin dose - consider clinical signals of overbasalization (basal dose >0.5 units/kg/day, elevated bedtime-morning glucose differential, hypoglycemia, high variability) 1
• If A1C remains above target despite optimized basal insulin, consider:
  • Adding a GLP-1 receptor agonist (preferred option before adding prandial insulin) 1, 4
  • Adding prandial insulin, usually starting with one dose with the largest meal or meal with greatest postprandial glucose excursion 1, 8
  • Initial prandial insulin dose: 4 units per day or 10% of basal dose 1, 4
  • Titrate prandial insulin by 1-2 units or 10-15% twice weekly based on postprandial glucose readings 1, 4

Patient Education Components

• Provide comprehensive education on blood glucose monitoring, nutrition, and hypoglycemia recognition and treatment 1, 2
• Educate patients on the progressive nature of type 2 diabetes and the role of insulin therapy to avoid using insulin as a threat or describing it as a sign of personal failure 1, 2
• Instruct patients in self-titration of insulin doses based on glucose monitoring to improve glycemic control 1
• Teach proper insulin injection technique, including site rotation to prevent lipodystrophy 3

Common Pitfalls and How to Avoid Them

• Delaying insulin therapy in patients not achieving glycemic goals - address patient concerns and misconceptions about insulin 2, 4
• Inadequate dose titration - use a systematic algorithm for dose adjustments based on SMBG 2, 7
• Not continuing metformin when initiating insulin - maintain metformin as it reduces insulin requirements and limits weight gain 1, 4
• Failing to recognize signs of overbasalization - watch for basal dose >0.5 units/kg, high bedtime-morning glucose differential, hypoglycemia, or high variability 1, 4
• Not considering technology - continuous glucose monitoring (CGM) can be useful in people with type 2 diabetes on insulin 1

By following this structured approach to insulin initiation and titration, clinicians can help patients achieve glycemic targets while minimizing the risk of hypoglycemia and other adverse effects.