Yes, you can and should initiate Lantus (insulin glargine) immediately in this patient.
Given his glucose of 369 mg/dL with classic hyperglycemic symptoms (fatigue, polydipsia, polyuria) after being off all medications for over a year, this patient meets clear criteria for immediate insulin initiation. 1
Why Insulin Now?
The 2025 ADA Standards explicitly state: "Consider insulin as the first injectable if symptoms of hyperglycemia are present, when A1C or blood glucose levels are very high (i.e., A1C >10% [>86 mmol/mol] or blood glucose ≥300 mg/dL [≥16.7 mmol/L])" 1. Your patient's glucose of 369 mg/dL clearly exceeds this threshold.
Starting Dose and Titration
Start with 10 units of Lantus once daily OR 0.1-0.2 units/kg/day 1. For a typical adult, 10 units is the standard conservative starting dose.
Titration Algorithm:
- Increase by 2 units every 3 days until fasting plasma glucose reaches target (typically 80-130 mg/dL) without hypoglycemia 1
- Alternative approach: increase by 1 unit daily if using more aggressive titration 2
- For hypoglycemia: reduce dose by 10-20% 1
The patient can self-titrate using this simple rule: if fasting glucose remains elevated over 3 consecutive days, increase by 2 units 3.
Timing and Administration
Administer once daily at bedtime (most common) or in the morning - Lantus provides approximately 24-hour coverage 4. The key is consistency in timing.
Critical Safety Counseling
Before sending him home with Lantus, ensure he understands:
Hypoglycemia recognition and treatment 4:
- Symptoms: sweating, tremor, confusion, dizziness, fast heartbeat
- Treatment: 15g fast-acting carbohydrates (juice, glucose tablets, candy)
- Prescribe glucagon for emergent hypoglycemia 1
Storage 4:
- Unopened vials: refrigerate (36-46°F)
- Opened vials: room temperature acceptable, discard after 28 days
- Never freeze
What Else to Consider
Continue or restart oral agents?
While initiating insulin, you can continue metformin if he was previously on it (not contraindicated). However, given his prolonged medication non-adherence, starting with insulin alone simplifies the regimen initially.
Follow-up timing:
- Reassess in 3-6 months maximum to avoid therapeutic inertia 1
- Earlier follow-up (2-4 weeks) recommended to review glucose logs and adjust dosing
Red flags requiring immediate referral:
- If he develops signs of diabetic ketoacidosis (fruity breath, abdominal pain, rapid breathing, confusion) 4
- Note: Do not use Lantus to treat DKA 4
Common Pitfall to Avoid
Overbasalization: Don't keep escalating basal insulin indefinitely without achieving fasting glucose goals. Maximum effective dose is typically 0.5-1.0 units/kg/day 2. If fasting glucose remains uncontrolled despite adequate basal dosing, he'll need prandial insulin added or transition to a basal-bolus regimen 1.
The bottom line: Start 10 units Lantus tonight, provide glucose meter and hypoglycemia education, prescribe glucagon, and schedule close follow-up for dose titration.