Insulin Administration Guideline
For adults with type 1 diabetes, initiate multiple daily injections (MDI) or continuous subcutaneous insulin infusion (CSII) using insulin analogs in a basal-bolus regimen, with automated insulin delivery systems offered to all patients; for insulin-naïve adults with type 2 diabetes, start with basal insulin at 0.3 units/kg/day (or 10 units if A1C <9%) and titrate every 2-3 days, advancing to basal-bolus or premixed insulin only if basal alone fails to achieve glycemic targets. 1, 2
Type 1 Diabetes: Insulin Initiation and Regimen
Preferred Regimen
- Use insulin analogs over human insulins to minimize hypoglycemia risk 1
- Implement either:
- Multiple daily injections (MDI): basal insulin + prandial insulin with each meal
- Continuous subcutaneous insulin infusion (CSII/pump therapy)
- Automated insulin delivery systems should be offered to all adults with type 1 diabetes 1
Dosing Strategy
- Educate patients on carbohydrate counting to match mealtime insulin doses
- Teach correction dose calculations based on:
- Current blood glucose
- Glycemic trends from continuous glucose monitoring
- Anticipated physical activity
- Sick-day management 1
Monitoring
- Early continuous glucose monitoring (CGM) is recommended to improve outcomes, quality of life, and minimize hypoglycemia 1
- Reassess insulin treatment plan every 3-6 months 1
Type 2 Diabetes: Stepwise Insulin Initiation
When to Start Insulin
Initiate insulin in the following scenarios:
- A1C >9% at diagnosis
- Uncontrolled diabetes despite optimal oral agents
- Severe hyperglycemia (blood glucose ≥300 mg/dL)
- Symptomatic hyperglycemia or catabolism 3, 2
Starting Regimen: Basal Insulin First
The preferred approach is basal insulin with stepwise intensification 2. This strategy provides better hypoglycemia outcomes than starting with premixed insulin 4.
Initial Dosing
- Augmentation therapy (adding to oral agents): 0.3 units/kg/day OR 10 units at bedtime 3, 5
- Replacement therapy (stopping oral agents): 0.6-1.0 units/kg/day, with 50% as basal and 50% as bolus divided before meals 3
Titration Protocol
Adjust basal insulin every 2-3 days using fasting glucose targets 5, 2:
- Fasting glucose <4.4 mmol/L (79 mg/dL): decrease by 2 units
- 4.4-7.0 mmol/L (79-126 mg/dL): no change
- 7.1-10.0 mmol/L (128-180 mg/dL): increase by 2 units
10.0 mmol/L (>180 mg/dL): increase by 4 units
Alternative: Increase by 1 unit daily until fasting glucose reaches 5.5 mmol/L (99 mg/dL) 5
When to Intensify Beyond Basal Insulin
If A1C remains >7% despite optimized basal insulin (typically 40-70 units/day), advance to:
Option 1: Basal-Plus (Add One Prandial Injection)
- Add rapid-acting insulin before the largest meal
- Start with 4 units or 10% of basal dose
- This approach causes less hypoglycemia than premixed insulin (0.8 vs 1.9 events per patient-year) 4
Option 2: Full Basal-Bolus
- Add rapid-acting insulin before all three meals
- Divide 50% of total daily dose as basal, 50% as bolus (split among meals)
- Provides slightly better A1C reduction than premixed insulin (7.0% vs 7.2%) but with similar hypoglycemia rates to basal-plus 4
Option 3: Premixed Insulin
- Start with 6-10 units twice daily (before breakfast and dinner)
- Targets daytime and postprandial hyperglycemia 5
- Caveat: Higher hypoglycemia risk (46% vs 33% with basal-plus) and less flexibility 4
Special Situations Requiring Basal-Bolus from Start
The "5S" situations where basal-bolus is preferred over basal-only initiation 6:
- Severe hyperglycemia (A1C >10%)
- Symptomatic diabetes with weight loss
- Sick diabetes (acute/chronic comorbidity)
- Special situations (pregnancy, childhood, adolescence)
- Secondary diabetes (pancreatic, drug-induced, endocrine disorders)
Insulin Types and Selection
Long-Acting Basal Insulins
- Insulin analogs (glargine, detemir, degludec) are preferred over NPH
- Advantages: improved duration of action, reduced nocturnal hypoglycemia risk 2
Rapid-Acting Prandial Insulins
- Insulin analogs (aspart, lispro, glulisine) or inhaled insulin preferred over regular human insulin 1
Glucose Monitoring
Type 1 Diabetes
- Continuous glucose monitoring (CGM) recommended early for all patients 1
- Provides real-time data for insulin dose adjustments
Type 2 Diabetes
- Self-monitoring of blood glucose for insulin titration
- CGM may improve control and can be considered in insulin-requiring patients 2
Hypoglycemia Management
Prevention Strategies
- Use insulin analogs over human insulins 1
- Basal-plus regimens cause less hypoglycemia than premixed insulin 4
- Educate on recognition and treatment of hypoglycemia 5
Treatment
- 15-20 grams of fast-acting carbohydrates
- Recheck glucose in 15 minutes
- Repeat if needed
Injection Technique and Site Rotation
Key Principles
- Rotate injection sites within the same anatomical region to prevent lipohypertrophy
- Common sites: abdomen (fastest absorption), thighs, buttocks, upper arms
- Maintain consistent site for same injection time (e.g., always abdomen for breakfast bolus)
Common Pitfall
Lipohypertrophy from repeated injections in the same spot causes erratic absorption - inspect sites regularly and rotate systematically
Insulin Storage
- Unopened vials/pens: refrigerate at 2-8°C (36-46°F)
- In-use insulin: room temperature up to 28 days (check specific product)
- Never freeze insulin
- Protect from direct heat and sunlight
Adherence and Practical Considerations
Barriers to Optimal Use
Nearly half of patients report missed or mistimed doses in the past 30 days, with key reasons being 7:
- Forgetting doses
- Being too busy or distracted
- Finding regimen too complicated
Solutions
- Simplify regimens when possible (basal-plus vs full basal-bolus)
- Use devices that record doses and provide reminders
- Consider automated insulin delivery systems for type 1 diabetes 1
Concomitant Medications
Continue metformin if possible - proven to reduce all-cause mortality and cardiovascular events in overweight patients with type 2 diabetes 3