What is the recommended protocol for initiating basal insulin therapy in an adult patient, including starting dose, titration, monitoring, and follow‑up?

Basal Insulin Initiation Protocol

Start basal insulin at 10 units per day or 0.1-0.2 units/kg/day, titrate by increasing 2 units every 3 days until fasting plasma glucose reaches target (typically 80-130 mg/dL), and assess adequacy at every visit while monitoring for hypoglycemia and overbasalization. 1

Starting Dose

• Initiate at 10 units per day OR 0.1-0.2 units/kg/day for basal analog insulin or bedtime NPH insulin 1
• Consider insulin as first-line injectable therapy when A1C >10% (>86 mmol/mol), blood glucose ≥300 mg/dL (≥16.7 mmol/L), or when hyperglycemic symptoms are present 1
• Prescribe glucagon for emergent hypoglycemia at initiation 1

Titration Protocol

Use an evidence-based titration algorithm: 1

• Increase dose by 2 units every 3 days to reach fasting plasma glucose goal without hypoglycemia 1
• Alternative approach: increase by 1 unit per day for NPH, insulin detemir, and glargine 100 units/mL, or 2-4 units once or twice per week for longer-acting preparations 2
• Continue titration up to approximately 0.5-1.0 units/kg/day in some cases 2

For hypoglycemia during titration: 1

• Determine the cause
• If no clear reason identified, lower dose by 10-20% 1

Target Goals

• Set individualized fasting plasma glucose goal (typically 80-130 mg/dL) 1, 2
• Use fasting plasma glucose values to guide basal insulin titration 1

Monitoring and Follow-Up

Assess insulin adequacy at every visit by evaluating: 1

• Achievement of fasting glucose targets
• Signs of overbasalization including:
  • Elevated bedtime-to-morning glucose differential 1
  • Elevated postprandial-to-preprandial glucose differential 1
  • Hypoglycemia (aware or unaware) 1
  • High glucose variability 1
  • Continuing dose escalation without meaningful fasting glucose reduction 2

Critical Pitfalls to Avoid

Overbasalization is a common error where providers continue escalating basal insulin doses without achieving meaningful fasting glucose improvement 1, 2. When this occurs:

• Do not continue increasing basal insulin indefinitely 2
• Re-evaluate therapy and consider adjunctive treatments 1
• If A1C remains above goal despite adequate basal insulin, add GLP-1 RA or dual GIP/GLP-1 RA (may use fixed-ratio products like IDegLira or iGlarLixi) 1
• Consider adding prandial insulin if postprandial glucose remains elevated despite optimized basal insulin 1

Choice of Basal Insulin

• Base selection on person-specific considerations, including cost 1
• Consider switching from evening NPH to basal analog if hypoglycemia develops or if morning dosing would improve adherence 1
• Second-generation basal insulins provide greater stability and flexibility with lower hypoglycemia risk 2, 3

Combination Therapy Considerations

• Continue metformin when starting insulin as it reduces weight gain, lowers required insulin dose, and decreases hypoglycemia compared to insulin alone 4
• Do not abruptly discontinue oral medications when initiating insulin due to rebound hyperglycemia risk 4
• For patients already on GLP-1 RA, consider fixed-ratio combination products 1