Insulin Dose Adjustment Strategy
This patient requires immediate intensification of both basal insulin and addition of prandial insulin coverage, as the current regimen is grossly inadequate for the degree of hyperglycemia present.
Critical Problems with Current Regimen
The total daily Lantus dose of 40 units (20 units twice daily) is insufficient for the severe hyperglycemia demonstrated by FBS averaging 165 mg/dL and evening glucose averaging 245 mg/dL 1.
The twice-daily Lantus dosing at 4 PM and morning is unconventional and suboptimal, as Lantus is designed for once-daily administration to provide 24-hour basal coverage 1, 2.
The elevated post-dinner glucose of 245 mg/dL indicates inadequate prandial insulin coverage, which cannot be addressed by basal insulin alone 1.
Metformin 1000 mg twice daily should be continued as the foundation therapy unless contraindicated, and this dose is appropriate 3, 4, 5.
Immediate Basal Insulin Adjustment
Consolidate the split Lantus doses into a single daily injection and aggressively titrate upward:
Combine the current 40 units total into a single daily dose of 40 units, administered at the same time each day (bedtime is often preferred) 1.
Increase the basal insulin by 4 units every 3 days until fasting glucose consistently reaches 80-130 mg/dL, as the current FBS of 165 mg/dL falls into the ≥180 mg/dL aggressive titration category when considering the overall pattern 1.
Continue titration without arbitrary dose limits, but recognize that when basal insulin exceeds 0.5 units/kg/day (approximately 35-40 units for an average-weight elderly female), adding prandial insulin becomes more appropriate than continuing to escalate basal insulin alone 1.
Add Prandial Insulin Coverage
The evening glucose of 245 mg/dL clearly indicates the need for mealtime insulin, not just basal adjustment:
Start with 4 units of rapid-acting insulin (such as lispro, aspart, or glulisine) before dinner, or alternatively use 10% of the current basal dose (approximately 4 units) 1.
Titrate the prandial insulin by 1-2 units every 3 days based on post-dinner glucose readings, targeting postprandial glucose <180 mg/dL 1.
If breakfast or lunch glucose values are also elevated, add prandial insulin before those meals sequentially, starting with the meal causing the greatest glucose excursion 1.
Foundation Therapy Optimization
Verify metformin continuation at current dose of 1000 mg twice daily, as this should be maintained with insulin therapy unless contraindicated by renal dysfunction (eGFR <30 mL/min/1.73m²) 3, 4, 5.
Consider increasing metformin to 2000-2500 mg daily in divided doses if tolerated and not contraindicated, as higher doses provide additional glucose-lowering benefit 3, 4.
Monitoring Requirements
Daily fasting blood glucose monitoring is essential during the titration phase to guide basal insulin adjustments 1.
Check pre-dinner and 2-hour post-dinner glucose to guide prandial insulin titration 1.
Assess for signs of overbasalization at each visit, including bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, and high glucose variability 1.
Critical Pitfalls to Avoid
Do not continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia with prandial insulin, as this leads to overbasalization with increased hypoglycemia risk and suboptimal control 1.
Do not delay adding prandial insulin when evening glucose remains in the 200s despite basal insulin optimization, as this clearly indicates inadequate mealtime coverage 1.
Do not discontinue metformin when intensifying insulin therapy, as the combination reduces total insulin requirements and provides complementary glucose-lowering effects 3, 5.
If hypoglycemia occurs, reduce the relevant insulin dose by 10-20% immediately and determine the cause 1.
Expected Outcomes
With proper basal-bolus therapy, fasting glucose should reach 80-130 mg/dL within 2-3 weeks of aggressive titration 1.
Postprandial glucose should improve to <180 mg/dL with appropriate prandial insulin coverage 1.
HbA1c reduction of 1.5-2% is achievable with this intensified regimen over 3 months 3, 1.