How to Initiate Insulin Glargine in Newly Diagnosed Type 2 Diabetes
In newly diagnosed type 2 diabetes, insulin glargine should NOT be the first-line therapy unless the patient presents with severe hyperglycemia (HbA1c >9%, fasting glucose ≥11.1 mmol/L [≥200 mg/dL], or blood glucose ≥250 mg/dL) or has symptoms of catabolism. For most newly diagnosed patients without these features, metformin plus lifestyle modifications remain the appropriate initial approach 1, 2.
When Insulin Glargine IS Indicated at Diagnosis
Initiate insulin glargine immediately in newly diagnosed patients who present with:
- HbA1c >9.0% 1
- Fasting plasma glucose ≥11.1 mmol/L (200 mg/dL) 1
- Random blood glucose ≥250 mg/dL 1, 2
- Symptomatic hyperglycemia with catabolic features (weight loss, ketonuria) 1, 2
These thresholds indicate severe beta-cell dysfunction requiring immediate insulin therapy to reverse glucotoxicity 1.
Starting Dose and Administration
Begin with 10 units subcutaneously once daily OR 0.1-0.2 units/kg body weight, depending on the degree of hyperglycemia 1, 2, 3:
- Administer at the same time each day (any time, but consistency is critical) 3
- Inject into abdomen, thigh, or deltoid 3
- Rotate injection sites to prevent lipodystrophy 3
- Do NOT dilute or mix with other insulins 3
Titration Strategy
Titrate the dose every 3 days based on fasting blood glucose until target of 5.5 mmol/L (100 mg/dL) is achieved 2, 4:
- Fasting glucose <4.4 mmol/L (80 mg/dL): Decrease by 2 units
- Fasting glucose 4.4-7.0 mmol/L (80-126 mg/dL): No change
- Fasting glucose 7.1-10.0 mmol/L (127-180 mg/dL): Increase by 2 units
- Fasting glucose >10.0 mmol/L (>180 mg/dL): Increase by 4 units 4
Alternatively, increase by 1 unit daily until fasting glucose target is reached 4. Most patients require 40-70 units daily to achieve HbA1c ≤7% 4.
Concomitant Therapy
Continue metformin when initiating basal insulin unless contraindicated 1, 2. Metformin reduces insulin requirements and prevents weight gain 1.
Consider adding one additional non-insulin agent (but not sulfonylureas, which increase hypoglycemia risk) 1.
Short-Term Intensive Approach for Severe Hyperglycemia
For newly diagnosed patients with HbA1c >9% or marked symptoms, consider short-term intensive insulin therapy (2 weeks to 3 months) using:
- Basal-bolus regimen (basal insulin plus mealtime rapid-acting insulin), OR
- Premixed insulin 2-3 times daily 1
After achieving glycemic control, transition to metformin-based oral therapy is equally effective as continuing insulin glargine and offers advantages in safety, cost, and convenience 5.
Monitoring Requirements
- Self-monitor fasting blood glucose daily during titration 2, 4
- Check HbA1c every 3 months and intensify therapy if not meeting targets 1, 2
- Monitor for hypoglycemia, especially during dose adjustments 1, 3
- Assess weight at each visit (expect ~3 kg gain over 6 months) 4
Critical Pitfall: Avoiding Insulin in Appropriate Candidates
The most common error is initiating insulin glargine in newly diagnosed patients who do NOT meet severity criteria. Current high-quality evidence strongly recommends SGLT-2 inhibitors or GLP-1 agonists over insulin for most patients due to superior mortality and cardiovascular benefits 1. Insulin glargine is "inferior to SGLT-2 inhibitors and GLP-1 agonists in reducing all-cause mortality and morbidity" 1.
When NOT to Use Insulin Glargine First-Line
For newly diagnosed patients with HbA1c <9% and no severe symptoms:
- Start metformin plus lifestyle modifications 1, 2
- Add SGLT-2 inhibitor or GLP-1 agonist if inadequate response after 3 months 1
- Reserve insulin glargine for later-stage disease when other agents fail 1
Expected Outcomes
With appropriate titration, expect: