How should Lantus (insulin glargine) be initiated in a patient with diabetes currently taking metformin (Metformin) 1000 mg bid and glipizide (Glipizide) 10 mg?

Initiating Lantus in a Patient on Metformin and Glipizide

Starting Dose

Start Lantus at 10 units once daily (or 0.1-0.2 units/kg body weight) administered at the same time each day, and continue metformin 1000 mg bid while discontinuing glipizide to prevent hypoglycemia. 1, 2

• The FDA label specifies a starting dose of 0.2 units/kg or up to 10 units once daily for insulin-naive type 2 diabetes patients 2
• The American Diabetes Association guidelines support this 10 units or 0.1-0.2 units/kg/day starting range 1
• Administer subcutaneously into the abdominal area, thigh, or deltoid, rotating injection sites to reduce lipodystrophy risk 2

Medication Management

Continue metformin at current dose (1000 mg bid) but discontinue glipizide when starting Lantus to minimize hypoglycemia risk. 3, 1

• Metformin combined with insulin provides superior glycemic control with less weight gain and lower insulin requirements compared to insulin alone 3, 4
• Metformin should be continued unless contraindicated, even when initiating or intensifying insulin therapy 3, 1
• Sulfonylureas like glipizide should be discontinued when starting basal insulin to prevent excessive hypoglycemia 1

Dose Titration Protocol

Increase Lantus by 2-4 units every 3 days based on fasting glucose levels until reaching target of 80-130 mg/dL. 1, 2, 5

Specific Titration Algorithm:

• If fasting glucose is 140-179 mg/dL: increase by 2 units every 3 days 1
• If fasting glucose is ≥180 mg/dL: increase by 4 units every 3 days 1
• If hypoglycemia occurs without clear cause: reduce dose by 10-20% immediately 1
• Target fasting plasma glucose: 80-130 mg/dL 1, 5

The Treat-to-Target study demonstrated that this systematic titration approach allows more patients to reach HbA1c ≤7% without nocturnal hypoglycemia 5. Patient self-titration using this algorithm is safe and effective, with the AT.LANTUS trial showing greater HbA1c reductions with patient-managed versus clinic-managed titration (-1.22% vs -1.08%) 5.

Monitoring Requirements

Check fasting blood glucose daily during titration and reassess every 3 days to adjust the dose. 1, 4

• Daily fasting glucose monitoring is essential during the titration phase 1
• Increase frequency of blood glucose monitoring during insulin regimen changes 2
• Reassess overall glycemic control and HbA1c every 3-6 months once stable 1

Critical Threshold: When to Add Prandial Insulin

When Lantus dose exceeds 0.5 units/kg/day (approximately 36-40 units for most adults) without achieving HbA1c goals, add prandial insulin rather than continuing to escalate basal insulin alone. 3, 1

Signs of "Overbasalization" requiring prandial insulin addition:

• Basal insulin dose >0.5 units/kg/day 1
• Bedtime-to-morning glucose differential ≥50 mg/dL 1
• Hypoglycemia episodes 1
• High glucose variability throughout the day 1
• Fasting glucose at target but HbA1c remains above goal after 3-6 months 1

If prandial insulin becomes necessary, start with 4 units of rapid-acting insulin before the largest meal (or 10% of basal dose) and titrate by 1-2 units every 3 days based on postprandial glucose readings 1.

Patient Education Essentials

Provide comprehensive education on injection technique, glucose monitoring, hypoglycemia recognition/treatment, and sick day management before initiating Lantus. 3, 1

• Teach proper insulin injection technique and site rotation 1
• Educate on recognition and treatment of hypoglycemia with 15 grams of fast-acting carbohydrate 1
• Instruct on self-monitoring of blood glucose and recording values 3, 1
• Review "sick day" management rules and insulin storage/handling 3, 1

Common Pitfalls to Avoid

• Never delay insulin initiation in patients not achieving glycemic goals with oral medications, as this prolongs hyperglycemia exposure and increases complication risk 1
• Never discontinue metformin when starting insulin unless contraindicated, as this leads to higher insulin requirements and more weight gain 3, 1
• Never continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia, as this causes overbasalization with increased hypoglycemia risk 1
• Never mix or dilute Lantus with any other insulin or solution due to its low pH 2, 4

Expected Outcomes

With appropriate initiation and titration, insulin glargine achieves equivalent glycemic control to NPH insulin but with significantly lower rates of hypoglycemia, especially nocturnal episodes 6, 7. Meta-analysis data show insulin glargine reduces overall symptomatic hypoglycemia by 11%, nocturnal hypoglycemia by 26%, severe hypoglycemia by 46%, and severe nocturnal hypoglycemia by 59% compared to NPH insulin 7.