How do you adjust insulin glargine (long-acting insulin) dosing for optimal glucose control?

Insulin Glargine Dose Adjustment Guidelines

Initial Dosing

For insulin-naive patients with type 2 diabetes, start with 10 units once daily or 0.1-0.2 units/kg body weight, administered at the same time each day. 1, 2

• For type 1 diabetes, the recommended starting dose is approximately one-third of total daily insulin requirements (typically 0.5 units/kg/day total, with 40-50% as basal insulin). 1, 2
• Patients with severe hyperglycemia (A1C ≥9%, blood glucose ≥300-350 mg/dL) require higher starting doses of 0.3-0.5 units/kg/day as total daily dose, often necessitating immediate basal-bolus therapy rather than basal insulin alone. 1
• Continue metformin unless contraindicated when initiating insulin therapy. 1

Standard Titration Algorithm

Increase basal insulin by 2-4 units every 3 days until fasting plasma glucose reaches 80-130 mg/dL. 1, 2

The specific titration schedule based on fasting glucose levels:

• If fasting glucose ≥180 mg/dL: Increase by 4 units every 3 days 1
• If fasting glucose 140-179 mg/dL: Increase by 2 units every 3 days 1
• If fasting glucose <80 mg/dL on more than 2 occasions per week: Decrease by 2 units 1

Alternative titration approach: Increase by 10-15% of current dose once or twice weekly until target is met. 1

Critical Threshold: When to Stop Escalating Basal Insulin

When basal insulin exceeds 0.5 units/kg/day and approaches 1.0 units/kg/day, add prandial insulin or a GLP-1 receptor agonist rather than continuing to escalate basal insulin alone. 1

Clinical signals of "overbasalization" that mandate adding prandial coverage include:

• Basal insulin dose >0.5 units/kg/day 1
• Bedtime-to-morning glucose differential ≥50 mg/dL 1
• Hypoglycemia episodes 1
• High glucose variability 1
• Fasting glucose at target but A1C remains elevated after 3-6 months 1

Adding Prandial Insulin

When basal insulin optimization fails to achieve A1C goals despite controlled fasting glucose, start prandial insulin with 4 units of rapid-acting insulin before the largest meal, or use 10% of the current basal dose. 1

• Titrate prandial insulin by 1-2 units or 10-15% every 3 days based on postprandial glucose readings. 1
• Rapid-acting insulin analogs provide better postprandial control than regular insulin. 1

Hypoglycemia Management

If hypoglycemia occurs without clear cause, immediately reduce the insulin dose by 10-20%. 1

• Do not wait for the next scheduled adjustment—act immediately when hypoglycemia is identified. 1
• Severe hypoglycemia warrants a 10-20% dose reduction. 1

Special Populations Requiring Dose Modifications

Hospitalized patients on high-dose home insulin (≥0.6 units/kg/day) should have their total daily dose reduced by 20% upon admission to prevent hypoglycemia. 1

• Elderly patients (>65 years), those with renal failure, or poor oral intake require lower doses (0.1-0.25 units/kg/day). 1
• During perioperative periods, reduce the insulin dose by approximately 25% the evening before surgery to achieve target glucose levels with decreased hypoglycemia risk. 3

Monitoring Requirements

Daily fasting blood glucose monitoring is essential during titration, with reassessments every 3 days during active dose adjustments. 1

• Assess adequacy of insulin dose at every clinical visit, specifically looking for signs of overbasalization. 1
• Check A1C every 3 months during intensive titration. 1

Common Pitfalls to Avoid

Do not continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia—this leads to suboptimal control and increased hypoglycemia risk. 1

• Fasting hyperglycemia reflects basal insulin adequacy; postprandial hyperglycemia requires prandial insulin, not more basal insulin. 1
• Do not delay adding prandial insulin when signs of overbasalization are present. 1
• Avoid waiting longer than 3 days between basal insulin adjustments in stable patients, as this unnecessarily prolongs time to glycemic targets. 1
• Never dilute or mix insulin glargine with any other insulin or solution due to its low pH. 1, 2

Administration Guidelines

Administer subcutaneously once daily at the same time each day into the abdominal area, thigh, or deltoid, rotating injection sites within the same region. 2

• Do not administer intravenously or via an insulin pump. 2
• Insulin glargine provides approximately 24 hours of coverage with a peakless profile, though some patients may require twice-daily dosing if once-daily administration fails to provide adequate 24-hour coverage. 1, 4