What is the appropriate starting dose of Lantus (insulin glargine) and carbohydrate ratio for a patient with a body mass index (BMI) of 38, significant weight gain, and elevated hemoglobin A1C (HbA1C) of 13.4%?

Starting Insulin Therapy for Severe Hyperglycemia

For this patient with HbA1c 13.4%, start Lantus at 20 units once daily at bedtime (0.2 units/kg × 103 kg ≈ 20 units), add rapid-acting insulin 4-6 units before each meal, and continue or add metformin if not already prescribed. 1, 2

Initial Insulin Regimen

Basal Insulin (Lantus) Dosing

• Start Lantus at 0.2 units/kg/day given the severe hyperglycemia (HbA1c 13.4%), which equals approximately 20 units once daily at bedtime for this 103 kg patient 1
• The higher end of the dosing range (0.2 vs 0.1 units/kg) is appropriate because HbA1c >10% indicates severe insulin deficiency 2, 3
• Administer at the same time each evening for consistent 24-hour coverage 4

Prandial (Mealtime) Insulin

• With HbA1c ≥12%, you must start both basal AND mealtime insulin simultaneously—basal insulin alone will not be sufficient 2
• Start rapid-acting insulin analog (aspart, lispro, or glulisine) at 4-6 units before each of the three main meals 1, 2
• This starting dose represents approximately 10% of the basal insulin dose per meal 1

Titration Protocol

Basal Insulin Adjustment

• Increase Lantus by 2 units every 3 days until fasting blood glucose reaches 100-130 mg/dL 1, 2
• Patient should perform self-titration using this algorithm based on morning fasting glucose readings 1
• Maximum basal dose should not exceed 0.5 units/kg/day (approximately 50 units for this patient) to avoid overbasalization 1

Prandial Insulin Adjustment

• Increase each mealtime insulin dose by 1-2 units twice weekly based on 2-hour postprandial glucose readings 5
• Target postprandial glucose <180 mg/dL 1
• Adjust each meal's insulin dose independently based on the glucose reading 2 hours after that specific meal 5

Carbohydrate Ratio and Correction Scale

Initial Approach

• Do not use carbohydrate counting or correction scales initially—use fixed mealtime doses as described above 1, 2
• Carbohydrate ratios are typically reserved for patients with more stable control and experience with insulin therapy 1
• Once glucose patterns stabilize over 2-4 weeks, you can transition to carbohydrate counting if the patient is motivated and capable 1

If Correction Doses Needed

• Add correction insulin only after basal and mealtime insulins are optimized 1
• Use a correction factor of 1 unit for every 50 mg/dL above target (e.g., if target is 150 mg/dL and glucose is 250 mg/dL, add 2 units) 1
• Reassess correction factor based on response and adjust accordingly 1

Essential Concurrent Medications

Metformin

• Start or continue metformin 1000 mg twice daily (if not contraindicated) as it reduces insulin requirements, limits weight gain, and improves insulin sensitivity 1, 2, 3
• Metformin combined with insulin is associated with decreased weight gain and lower insulin doses compared to insulin alone 3

Consider GLP-1 Receptor Agonist

• Adding a GLP-1 RA (such as liraglutide) should be strongly considered once initial glucose control is achieved, as it provides additional HbA1c reduction of 1.0-1.5% with weight loss rather than weight gain 6
• This is particularly important given the patient's BMI of 38 and recent weight gain from stress eating 6

Critical Monitoring Requirements

Blood Glucose Monitoring

• Check fasting glucose every morning before breakfast to guide Lantus titration 1, 2
• Check glucose 2 hours after each meal to guide prandial insulin adjustments 5
• Check before bed to assess evening coverage 1

Hypoglycemia Management

• For any blood glucose <70 mg/dL, reduce the corresponding insulin dose by 10-20% 5, 6
• Prescribe glucagon emergency kit and educate patient on recognition and treatment of hypoglycemia 6
• The risk of severe hypoglycemia with Lantus is lower than with NPH insulin (46% reduction), but vigilance is still required 4

Common Pitfalls to Avoid

Therapeutic Inertia

• Do not delay or undertitrate insulin—this patient's HbA1c of 13.4% requires aggressive treatment 2, 6
• Reassess every 2-3 weeks initially, then every 3 months once stable 6

Overbasalization

• Watch for signs of excessive basal insulin: bedtime-to-morning glucose differential >50 mg/dL, hypoglycemia, or basal dose >0.5 units/kg 1
• If these occur, reduce basal insulin and ensure adequate prandial coverage 1

Weight Gain Concerns

• Expected weight gain is 1-2 kg with insulin therapy, but this can be mitigated by adding metformin and eventually a GLP-1 RA 3, 7, 8
• Address the underlying stress eating through behavioral support and counseling 1

Patient Education Priorities

• Provide comprehensive education on insulin injection technique, blood glucose monitoring, hypoglycemia recognition/treatment, and dietary management before discharge 1, 3
• Equip patient with self-titration algorithm for both basal and prandial insulin 1
• Use the shortest needles (4-6 mm) to reduce pain and avoid intramuscular injection 3
• Rotate injection sites to prevent lipohypertrophy which impairs insulin absorption 3

Expected Outcomes

• Target HbA1c reduction of 3-4% over 3-6 months with this regimen 2, 8
• Fasting glucose should reach target (100-130 mg/dL) within 2-4 weeks with proper titration 1, 8
• Once HbA1c approaches 8-9%, consider adding GLP-1 RA and potentially reducing insulin doses 6