What is the recommended starting dose of glargine (insulin glargine) for a woman with type 2 diabetes mellitus (T2DM) treated with metformin (biguanide) alone and an elevated Hemoglobin A1C (HbA1C) level?

Recommended Starting Dose of Glargine

For a 57kg woman with type 2 diabetes on metformin alone with A1C >15%, start insulin glargine at 11 units once daily (0.2 units/kg/day), administered at the same time each day, and strongly consider immediate basal-bolus insulin therapy given the severe hyperglycemia. 1, 2

Rationale for Dosing in Severe Hyperglycemia

• The FDA label recommends a starting dose of 0.2 units/kg or up to 10 units once daily for insulin-naive patients with type 2 diabetes 2
• For this 57kg patient, weight-based dosing yields: 57kg × 0.2 units/kg = 11.4 units, rounded to 11 units 2
• With A1C >15%, this represents severe hyperglycemia that warrants consideration of higher starting doses (0.3-0.5 units/kg/day as total daily dose) with immediate basal-bolus coverage rather than basal insulin alone 1
• The American Diabetes Association recommends that patients with blood glucose ≥300-350 mg/dL and/or A1C 10-12% with symptomatic or catabolic features should start basal-bolus insulin immediately 1

Critical Threshold: When Basal-Only is Insufficient

• At A1C >15%, basal insulin alone will likely be inadequate 1, 3
• Consider starting with 0.3-0.5 units/kg/day as total daily dose (17-28 units for this patient), split 50% basal and 50% prandial insulin 1
• This would mean approximately 9-14 units of glargine once daily PLUS 3-5 units of rapid-acting insulin before each meal 1

Aggressive Titration Protocol Required

• Increase glargine by 4 units every 3 days if fasting glucose ≥180 mg/dL 1
• Increase by 2 units every 3 days if fasting glucose 140-179 mg/dL 1
• Target fasting plasma glucose: 80-130 mg/dL 1
• When basal insulin exceeds 0.5 units/kg/day (>28 units for this patient), add prandial insulin rather than continuing to escalate basal insulin alone 1

Essential Foundation Therapy

• Continue metformin unless contraindicated, as it provides complementary glucose-lowering effects and reduces total insulin requirements 1, 4
• Metformin combined with insulin resulted in HbA1c concentrations 10% lower than insulin alone, with 29% less insulin needed and without significant weight gain 4

Common Pitfalls to Avoid

• Delaying insulin intensification at this A1C level prolongs exposure to severe hyperglycemia and increases complication risk 1
• Starting with only 10 units may be insufficient given the severity of hyperglycemia (A1C >15%) 1, 3
• Failing to add prandial insulin when basal insulin exceeds 0.5 units/kg/day leads to "overbasalization" with increased hypoglycemia risk and suboptimal control 1
• Relying solely on sliding scale insulin without optimizing basal insulin first is ineffective for long-term management 1

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during titration 1
• Reassess adequacy of insulin dose at every clinical visit, looking for signs of overbasalization 1
• Check HbA1c every 3 months during intensive titration 1

Alternative Consideration

• GLP-1 receptor agonists combined with basal insulin may provide superior glycemic control with less weight gain and hypoglycemia than insulin intensification alone 5, 3
• However, at A1C >15%, non-insulin agents alone will not achieve adequate control 3