What insulin should a 59-year-old female patient with newly diagnosed type 2 diabetes mellitus and hyperglycemia start with?

Initial Insulin Therapy for Newly Diagnosed Type 2 Diabetes with Hyperglycemia

Immediate Recommendation

Start basal insulin glargine (Lantus) at 10 units once daily at bedtime, combined with metformin, and titrate aggressively by 2-4 units every 3 days until fasting glucose reaches 80-130 mg/dL. 1, 2

Rationale for Basal Insulin as First-Line

For a 59-year-old newly diagnosed with type 2 diabetes and hyperglycemia, basal insulin is the preferred initial insulin regimen unless there are signs of severe metabolic decompensation 1, 2. The American College of Physicians recommends starting with long-acting basal insulin (glargine, detemir, or degludec) at 0.1-0.2 units/kg/day or a flat dose of 10 units once daily 1, 2. Long-acting analogues like glargine are preferred over NPH insulin because they cause less nocturnal hypoglycemia and have more predictable pharmacokinetics 2, 3.

However, if this patient presents with HbA1c ≥10%, blood glucose ≥300-350 mg/dL, or symptomatic/catabolic features (unintentional weight loss, ketosis), immediately start basal-bolus insulin therapy instead at 0.3-0.5 units/kg/day total daily dose, split 50% basal and 50% prandial 1, 4, 2.

Specific Dosing Algorithm

For Mild-to-Moderate Hyperglycemia (HbA1c 7.5-9.5%, glucose <300 mg/dL):

• Starting dose: 10 units glargine once daily at bedtime OR 0.1-0.2 units/kg/day 1, 2, 5
• Titration schedule: Increase by 2 units every 3 days if fasting glucose 140-179 mg/dL; increase by 4 units every 3 days if fasting glucose ≥180 mg/dL 1, 6
• Target: Fasting plasma glucose 80-130 mg/dL 1, 2
• If hypoglycemia occurs: Reduce dose by 10-20% immediately 1

For Severe Hyperglycemia (HbA1c ≥10%, glucose ≥300 mg/dL, or symptomatic):

• Starting dose: 0.3-0.5 units/kg/day total daily insulin 1, 4
• Split: 50% as basal glargine once daily + 50% as rapid-acting insulin (lispro, aspart, or glulisine) divided before three meals 1, 4
• Example for 70 kg patient: Total 21-35 units/day → 10-17 units glargine at bedtime + 4 units rapid-acting before each meal 4

Essential Concurrent Oral Medication Management

Continue metformin unless contraindicated (renal impairment with eGFR <30 mL/min/1.73m²) 1, 2, 3, 6. Metformin combined with insulin reduces weight gain, lowers total insulin requirements, and decreases hypoglycemia risk compared to insulin alone 3, 6, 7. The target metformin dose is at least 1000 mg twice daily (2000 mg total), up to 2500 mg/day maximum 1.

Discontinue sulfonylureas when starting insulin to reduce hypoglycemia risk, especially if advancing beyond basal-only insulin 1, 4.

Critical Threshold: When to Add Prandial Insulin

Stop escalating basal insulin when the dose exceeds 0.5 units/kg/day (approximately 35 units for a 70 kg patient) 1, 2. At this threshold, adding prandial insulin becomes more appropriate than continuing to increase basal insulin alone 1, 2.

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
• HbA1c remains above goal after 3-6 months despite fasting glucose 80-130 mg/dL 1, 2

How to add prandial insulin:

• Start with 4 units rapid-acting insulin before the largest meal OR 10% of current basal dose 1
• Titrate by 1-2 units every 3 days based on 2-hour postprandial glucose readings 1
• Target postprandial glucose <180 mg/dL 1

Patient Education Essentials

Provide immediate education on:

• Daily fasting blood glucose monitoring during titration phase 1, 2, 5
• Hypoglycemia recognition and treatment: Treat at glucose ≤70 mg/dL with 15 grams fast-acting carbohydrate 1
• Proper injection technique and site rotation to prevent lipohypertrophy 3
• Sick day management: Never stop insulin during illness; check glucose more frequently 4
• Insulin storage and handling 1

The shortest needles (4-mm pen needles) are safest, most effective, and less painful, and should be first-line choice 3.

Common Pitfalls to Avoid

• Never delay insulin initiation in patients not achieving glycemic goals with oral medications alone, as this prolongs hyperglycemia exposure and increases complication risk 1, 2
• Never use sliding scale insulin as monotherapy for type 2 diabetes; it treats hyperglycemia reactively rather than preventing it 1, 6
• Never abruptly discontinue oral medications when starting insulin due to risk of rebound hyperglycemia 3
• Never continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia, as this leads to increased hypoglycemia risk without improved control 1, 2
• Never discontinue metformin when starting insulin unless contraindicated, as this leads to higher insulin requirements and more weight gain 1, 3, 6

Monitoring and Follow-up Schedule

• During active titration: Check fasting glucose daily and adjust dose every 3 days 1, 5
• Once stable: Reassess every 3-6 months with HbA1c measurement 1
• Follow-up visit: Schedule within 2-4 weeks to assess initial response, adherence, and side effects 4

Expected Outcomes

With appropriate basal insulin therapy, HbA1c reductions of 1.5-2.5% are achievable 5, 7. Approximately 50% of patients can achieve HbA1c ≤7% with insulin doses around 40-70 units/day 5. Weight gain of approximately 2-3 kg over 6 months is expected 8, 5, 7.