For an adult with type 1 diabetes whose fasting blood glucose is 262 mg/dL and 351 mg/dL, currently on 20 U insulin glargine (Lantus) overnight and a carbohydrate‑to‑insulin ratio of 1 U per 10 g, how should the basal insulin dose be increased and what correction bolus should be added for each glucose reading?

Insulin Dose Adjustment for Elevated Fasting Blood Glucose

Increase Lantus by 4 units every 3 days until fasting glucose reaches 80–130 mg/dL, and reassess the carbohydrate-to-insulin ratio after basal optimization. 1

Immediate Basal Insulin Titration

• Aggressive basal escalation is required: With fasting glucose values of 262 mg/dL and 351 mg/dL, increase Lantus by 4 units every 3 days until fasting glucose consistently falls within the target range of 80–130 mg/dL. 1
• The current dose of 20 units is profoundly inadequate for these glucose levels; fasting glucose ≥180 mg/dL specifically warrants 4-unit increments rather than the standard 2-unit increases used for glucose 140–179 mg/dL. 1
• Continue this titration schedule every 3 days, checking fasting glucose daily to guide adjustments. 1

Critical Threshold Monitoring

• Stop basal escalation when the dose approaches 0.5 units/kg/day (approximately 35–50 units for most adults) without achieving fasting targets; at this threshold, add prandial insulin rather than continuing basal increases to avoid "over-basalization." 1
• Clinical signals that basal insulin has become excessive include: dose >0.5 units/kg/day, bedtime-to-morning glucose differential ≥50 mg/dL, any hypoglycemia episodes, or high glucose variability. 1

Carbohydrate Coverage Assessment

• Do not adjust the carb ratio (1:10) until basal insulin is optimized. Fasting hyperglycemia reflects inadequate basal coverage, not meal coverage; the carb ratio addresses postprandial excursions, which cannot be accurately assessed when fasting glucose is uncontrolled. 1
• Once fasting glucose stabilizes at 80–130 mg/dL for 3–5 days, evaluate 2-hour postprandial glucose values to determine if the 1:10 ratio requires adjustment. 1
• If postprandial glucose consistently exceeds 180 mg/dL after basal optimization, tighten the ratio (e.g., from 1:10 to 1:8) by increasing mealtime insulin by 1–2 units every 3 days. 1

Monitoring Protocol During Titration

• Check fasting glucose every morning to guide the next basal dose adjustment. 1
• Measure glucose before each meal and at bedtime (minimum 4 times daily) to detect patterns and prevent hypoglycemia. 1
• If any glucose reading falls <70 mg/dL, reduce the implicated insulin dose by 10–20% immediately and treat with 15 g of fast-acting carbohydrate. 1

Expected Timeline and Outcomes

• With 4-unit increments every 3 days, fasting glucose should reach target within 2–3 weeks of aggressive titration. 1
• Approximately 68% of patients achieve mean glucose <140 mg/dL with properly titrated basal-bolus therapy, compared with 38% using inadequate regimens. 1
• Once basal insulin is optimized, reassess the carb ratio; if postprandial glucose remains elevated, the ratio can be adjusted independently without affecting fasting control. 1

Common Pitfalls to Avoid

• Do not delay basal dose escalation when fasting glucose consistently exceeds 180 mg/dL; prolonged hyperglycemia increases complication risk. 1
• Do not adjust the carb ratio prematurely—fasting hyperglycemia must be corrected first, as uncontrolled basal glucose distorts postprandial patterns. 1
• Never continue escalating basal insulin beyond 0.5–1.0 units/kg/day without addressing postprandial hyperglycemia with prandial insulin adjustments; this leads to over-basalization with increased hypoglycemia risk. 1
• Do not rely solely on correction insulin without adjusting scheduled basal doses; correction doses supplement, not replace, scheduled insulin. 1

Foundation Therapy Considerations

• Continue metformin at maximum tolerated dose (up to 2,000–2,550 mg daily) when intensifying insulin; metformin reduces total insulin requirements by 20–30% and provides superior glycemic control. 1
• If the patient is not on metformin, consider adding it to reduce insulin needs and improve overall control. 1