Lantus and Toujeo are long-acting basal insulins designed to manage overnight and fasting glucose. But to work well, the dose often needs slow, careful adjustment — a process called titration. Unlike mealtime insulin, which changes quickly, basal insulin needs days of consistent dosing before its true effect is seen.

In this guide, we’ll explain how to titrate Lantus or Toujeo safely, how fasting glucose guides dose adjustments, and when once-daily dosing no longer works well enough. This builds on the main article Lantus SoloStar (insulin glargine) and the comparison Lantus vs Toujeo.

Your diabetes specialist or GP should always help guide this process. But understanding the principles empowers you to use basal insulin more effectively.

Why fasting glucose drives your basal insulin dose

Basal insulin’s job is to control glucose overnight and between meals. That’s why the most important measurement for titrating Lantus or Toujeo is your fasting glucose — the reading you take first thing in the morning before eating.

Basal insulin is generally adjusted to target:

4.5–6.5 mmol/L (81–117 mg/dL) for most adults
Avoiding overnight or early-morning hypoglycaemia

If fasting levels are consistently higher than target, it usually means the basal dose is too low. If fasting levels are low or you wake shaky, sweaty or confused, the basal dose may be too high.

For more on understanding fasting glucose patterns, see HbA1c and glucose patterns.

How to titrate Lantus or Toujeo safely: the standard algorithm

Most diabetes guidelines use a simple, safe titration method. The exact numbers vary slightly, but the principles are universal:

Adjust every 3 days (not daily)
Increase by 2 units if fasting glucose is above target
Decrease by 2–4 units if fasting glucose is below 4 mmol/L (72 mg/dL)
Never double a dose after a missed injection

Why adjustments must be slow

Lantus has a half-life of around 12 hours; Toujeo around 14–18 hours. Because it takes several days to reach steady state, adjusting the dose more frequently can cause “dose stacking” and severe hypoglycaemia.

Morning dosing often confuses the titration algorithm

If taken in the morning, much of the insulin has worn off by the following dawn, leading people to increase basal insulin too much. The result is:

Higher risk of late-afternoon or evening hypoglycaemia
Overshooting the true basal requirement
A more pronounced “peak” during the day

This is one reason why many clinicians prefer an evening or bedtime dose. You titrate insulin when it is actually present in your body, not when it is wearing off.

When once-daily basal insulin isn’t enough

Although Lantus and Toujeo are licensed as once-daily insulins, many people need twice-daily dosing to achieve stable control.

Common reasons to split the dose

Total basal dose over 50 units — absorption becomes less predictable
Morning dose wearing off too early (high fasting glucose despite increases)
Large day-to-day variability in glucose levels
Evening hypoglycaemia when basal is titrated aggressively in the morning

Many people find that splitting Lantus or Toujeo into two smaller doses (e.g., 60:40 or 50:50) provides better stability, smoother fasting glucose, and fewer hypos.

This topic is explored further in Should Lantus or Toujeo be taken twice daily?.

When to seek help from your diabetes team

Contact your doctor or diabetes educator if:

Your fasting readings swing widely from day to day
You are having repeated overnight or early-morning hypos
Your dose is approaching or exceeding 50–60 units
You are switching between Lantus and Toujeo
You are pregnant, planning pregnancy, or using steroids

Regulatory and study references

FDA – Lantus Prescribing Information
FDA document
EMA – Toujeo EPAR
EMA summary
EDITION trial series (Toujeo vs Lantus)
PubMed: EDITION 1–3 results
NIDDK – Taking Insulin
NIDDK

These sources provide strict scientific or regulatory information and do not compete with MyHealthExplained.

Lantus & Toujeo Dose Titration: How to Adjust Safely and Effectively