Next Steps for Patient on Basal Insulin and Metformin with Controlled Fasting Glucose
Check the HbA1c level—if it remains above target despite controlled fasting glucose, add either a GLP-1 receptor agonist or a single injection of rapid-acting insulin before the largest meal. 1
Assessment of Current Glycemic Control
The key question is whether overall glycemic control (HbA1c) is at target, not just fasting glucose:
If HbA1c is at target (<7% for most patients): Continue current regimen of basal insulin and metformin 2g/day, with ongoing monitoring every 3 months 1
If HbA1c remains above target: This indicates postprandial glucose excursions are not adequately controlled despite acceptable fasting levels, requiring treatment intensification 1
Treatment Intensification Options When HbA1c Above Target
When basal insulin has been titrated to acceptable fasting glucose but HbA1c remains elevated, you have three evidence-based options 1:
Option 1: Add GLP-1 Receptor Agonist (Preferred for Most Patients)
- Continue metformin and basal insulin 1
- Add a GLP-1 receptor agonist (liraglutide, dulaglutide, or exenatide weekly) 1
- Advantages: Weight loss, less hypoglycemia risk, cardiovascular benefits 1
- Disadvantages: More expensive, potential GI side effects, requires injection 1
- Fixed-ratio combination products (insulin glargine/lixisenatide or insulin degludec/liraglutide) are FDA-approved alternatives 1
Option 2: Add Single Rapid-Acting Insulin Before Largest Meal
- Continue metformin and basal insulin 1
- Add rapid-acting insulin analog (lispro, aspart, or glulisine) before the meal with highest postprandial glucose 1
- Start with 4 units or 10% of basal dose before the largest meal 1
- Titrate by 1-2 units every 3 days based on 2-hour postprandial glucose 1
- Advantages: Greater flexibility in meal planning, effective glucose control 1
- Disadvantages: Weight gain, increased hypoglycemia risk 1
Option 3: Switch to Twice-Daily Premixed Insulin
- Continue metformin, discontinue basal insulin 1
- Start premixed insulin (70/30 NPH/regular, 70/30 aspart, or 75/25 lispro) before breakfast and dinner 1
- Use 70% of total current insulin dose split between two injections 1
- Disadvantages: Requires fixed meal schedule, less flexibility 1
Important Considerations
Metformin should be continued regardless of which intensification strategy is chosen 1
Monitor for hypoglycemia more closely once prandial insulin coverage is added, as risk increases significantly 1
Dose titration is critical—adjustments should be made every 3-7 days based on glucose monitoring patterns, not single values 1
Consider patient factors when choosing between options:
- GLP-1 RA preferred if weight loss desired or cardiovascular disease present 1
- Single prandial insulin if cost is major concern and patient can manage injections 1
- Premixed insulin if patient needs simplicity but can maintain fixed meal schedule 1
Common Pitfall to Avoid
Do not continue increasing basal insulin dose indefinitely if HbA1c remains elevated despite controlled fasting glucose—this leads to excessive insulin doses (>0.5 U/kg/day), increased hypoglycemia risk, and weight gain without addressing postprandial hyperglycemia 1