How do you initiate insulin therapy in a patient?

How to Start a Patient on Insulin

For patients with type 2 diabetes requiring insulin, initiate basal insulin at 10 units once daily or 0.1-0.2 units/kg/day, continuing metformin, and titrate the dose every few days based on fasting blood glucose until target is achieved. 1, 2

Initial Assessment and Timing

Consider insulin initiation when:

• HbA1c ≥9% despite oral agents 3, 1
• Blood glucose ≥300-350 mg/dL with HbA1c 10-12%, especially if symptomatic with polyuria, polydipsia, or weight loss 3, 1
• Severe hyperglycemia with ketosis or ketoacidosis (requires immediate insulin regardless of diabetes type) 3

Selecting the Initial Regimen

For Type 2 Diabetes (Most Common Scenario)

Start with basal insulin alone - this is the most convenient and appropriate initial regimen for most patients 1, 2:

• Dosing options: Either 10 units once daily (fixed dose) OR 0.1-0.2 units/kg/day (weight-based), with higher end of range for more severe hyperglycemia 3, 1, 4
• Preferred agents: Long-acting analogs (glargine, detemir, or degludec) 3, 1
• Timing: Once daily at the same time each day (can be any time, but consistency is key) 4
• Injection site: Subcutaneous into abdomen, thigh, or deltoid, rotating sites within same region 4

Exception - severe presentation: If blood glucose ≥250 mg/dL with HbA1c ≥8.5% and symptomatic, or if ketosis/ketoacidosis present, start basal PLUS mealtime insulin immediately 3

For Type 1 Diabetes

Start multiple daily injections from diagnosis - approximately one-third of total daily insulin requirement as basal, with remainder as short-acting premeal insulin 1, 2

Medication Management During Initiation

Continue metformin when starting basal insulin 1, 2

Consider continuing:

• One additional non-insulin agent (if already on it) 3, 1
• Thiazolidinediones or SGLT2 inhibitors to reduce total insulin dose (though use thiazolidinediones cautiously in heart failure risk and note SGLT2 inhibitor ketoacidosis risk) 3

Discontinue when moving beyond simple basal insulin:

• Sulfonylureas 3, 1
• DPP-4 inhibitors 3, 1
• GLP-1 receptor agonists 3, 1

Dose Titration Protocol

Equip patients with self-titration algorithm - this improves glycemic control significantly 3, 1:

• Target: Fasting blood glucose <100 mg/dL (5.5 mmol/L) 5
• Titration frequency: Increase dose every 3 days or once-twice weekly 1, 5
• Adjustment amount: Increase by 2-4 units or 10-15% based on average fasting glucose over previous 3 days 1, 5
• Specific algorithm example: If fasting glucose ≥100-120 mg/dL, increase by 2 units; if ≥120-140 mg/dL, increase by 4 units; if ≥140-180 mg/dL, increase by 6-8 units 5
• Safety check: Hold increases if blood glucose <72 mg/dL (4.0 mmol/L) 5

When to Intensify Beyond Basal Insulin

Add mealtime coverage when:

• Basal insulin titrated to achieve target fasting glucose BUT HbA1c remains above goal 3, 1
• Signs of "overbasalization" appear: basal dose >0.5 units/kg, large bedtime-morning glucose differential, hypoglycemia, or high glucose variability 2

Options for intensification:

• Add GLP-1 receptor agonist 3, 1
• Add 1-3 injections of rapid-acting insulin (lispro, aspart, or glulisine) before meals, starting at 4 units, 0.1 units/kg, or 10% of basal dose 1
• Consider premixed insulin twice daily (though less optimal for postprandial control) 3

Critical Patient Education Components

Provide comprehensive education on: 1, 2

• Self-monitoring of blood glucose (frequency based on regimen complexity)
• Recognition, prevention, and treatment of hypoglycemia
• Proper injection technique and site rotation to avoid lipodystrophy 4
• Diet and exercise modifications
• The progressive nature of type 2 diabetes

Address psychological barriers: 3

• Explain insulin is NOT a punishment or failure, but the best treatment for glucose control
• Reassure that injections are typically not painful with modern thin needles
• Emphasize benefits: improved energy, vision, sleep, and prevention of long-term complications

Common Pitfalls to Avoid

Do not delay insulin therapy in patients failing to achieve glycemic goals with oral agents 1, 2

Avoid clinical inertia - timely dose titration after initiation is essential 3, 1

Never use insulin as a threat or describe it as a sign of personal failure 2

Watch for lipodystrophy - repeatedly injecting into same areas causes poor absorption and hyperglycemia; sudden site change to unaffected area can cause hypoglycemia 4

Increase glucose monitoring frequency during any insulin regimen changes 3, 4