Lantus Dose Adjustment for Elevated Fasting Blood Glucose
Immediate Lantus Dose Increase
Increase Lantus by 4 units to 40 units daily, given that your fasting blood glucose is 235 mg/dL (≥180 mg/dL). 1
The American Diabetes Association's evidence-based titration algorithm specifies that when fasting glucose is ≥180 mg/dL, basal insulin should be increased by 4 units every 3 days until target glucose levels (80-130 mg/dL) are reached. 1 Continue this systematic uptitration every 3 days, increasing by 4 units each time if fasting glucose remains ≥180 mg/dL, or by 2 units if it falls to 140-179 mg/dL. 1
Carbohydrate Ratio Calculation
Your insulin-to-carbohydrate ratio should be approximately 1:12 (1 unit per 12 grams of carbohydrate). 1
For type 1 diabetes, total daily insulin requirements typically range from 0.4 to 1.0 units/kg/day, with 0.5 units/kg/day being typical for metabolically stable patients. 1 At 68 kg, this suggests a total daily dose of approximately 34 units (0.5 × 68). Since you're currently on 36 units of Lantus alone, your total daily dose is already in the appropriate range, but you need better distribution between basal and bolus insulin.
The "500 rule" for calculating carb ratios: 500 ÷ total daily insulin dose = grams of carbohydrate covered by 1 unit. With a projected total daily dose of ~48 units (after increasing Lantus and accounting for mealtime insulin), this yields 500 ÷ 48 ≈ 10-12 grams per unit. Start with 1:12 and adjust based on 2-hour postprandial glucose readings.
Correction Scale (Insulin Sensitivity Factor)
Your correction factor should be 1 unit per 50 mg/dL above target (using a target of 120 mg/dL). 1
The "1800 rule" for calculating correction factors: 1800 ÷ total daily insulin dose = mg/dL drop per 1 unit of insulin. With a total daily dose of ~48 units, this yields 1800 ÷ 48 ≈ 38-40 mg/dL per unit. For safety and to account for your relatively low BMI (21), use a more conservative 1:50 ratio initially. 1
Critical Monitoring and Next Steps
Monitor fasting blood glucose daily and continue increasing Lantus by 4 units every 3 days until fasting glucose reaches 80-130 mg/dL. 1
Watch for overbasalization: If your Lantus dose exceeds 0.5 units/kg/day (34 units for your weight) and approaches 1.0 units/kg/day (68 units), you need to add or optimize prandial insulin rather than continuing to escalate basal insulin alone. 1 Signs of overbasalization include a bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, and high glucose variability. 1
If A1C remains elevated after 3-6 months despite achieving fasting glucose targets, add prandial insulin before the meal causing the greatest glucose excursion, starting with 4 units of rapid-acting insulin (or 10% of basal dose). 1
Common Pitfalls to Avoid
Do not delay dose adjustments: Timely titration is essential for achieving glycemic goals. 1 Your current fasting glucose of 235 mg/dL requires immediate action.
Do not continue escalating basal insulin indefinitely: Once Lantus exceeds 0.5-1.0 units/kg/day without achieving A1C goals, this signals insufficient mealtime insulin coverage, not inadequate basal insulin. 1
If hypoglycemia occurs (blood glucose <70 mg/dL), determine the cause and reduce the insulin dose by 10-20%. 1 However, at your current glucose levels, this is not an immediate concern.