How fast does Long insulin start working?

It usually starts lowering blood sugar within 90 minutes of injection.

When is the peak effect?

Peak effect occurs after about a few hours.

How long does it last?

The total duration of action is around 24 hours.

Long-acting (Basal)

Long-acting insulins have a slow onset and no pronounced peak, providing basal coverage for up to 24–42 hours. Used once daily for steady background insulin.

Onset

min

Fast

Time until it starts working after injection.

Peak

Minimal / flat

When effect is strongest (may be minimal for some long-acting insulins).

Duration

approx

Total time the insulin continues to act.

Activity curve (illustrative)

This stylized curve shows a typical onset, peak, and duration profile for Long insulins. For education only.

How it works

Long

Long-acting insulins are modified to release slowly over time, providing steady insulin levels. They start working within 1–2 hours, have minimal or no peak, and last 24–42 hours.

Typical use

Usually injected once daily at the same time each day to maintain baseline insulin levels. Can be combined with rapid-acting insulins for meal-time control.

Storage & handling

Keep refrigerated (2–8°C). Opened pens or vials may be stored at room temperature for up to 28 days (Tresiba up to 56 days).

Frequently asked questions

How often should I inject long-acting insulin and what time is best?

Does long-acting insulin have a peak? What if I wake up with high glucose?

What happens if I change the injection time because of travel or fasting during festivals in India?

How should I rotate injection sites and store my insulin in Indian summer?

Brands

Representative brands you may see in India (not exhaustive).

Lantus

₹730

Manufacturer:: Sanofi
Strength:: 100 IU/mL
Forms:: PenCartridgeVial

Storage: Keep refrigerated (2–8°C). Opened pens may be stored at room temperature for 28 days.

Long-acting insulin glargine that provides steady basal insulin for up to 24 hours.

Levemir

₹1,017

Manufacturer:: Novo Nordisk
Strength:: 100 IU/mL
Forms:: PenCartridge

Storage: Refrigerate between 2–8°C. Do not freeze. Once opened, stable for 42 days.

Long-acting insulin detemir with a relatively flat action profile.

Tresiba

₹1,207

Manufacturer:: Novo Nordisk
Strength:: 100 IU/mL
Forms:: Pen

Storage: Refrigerate (2–8°C). In-use pens stable for 56 days at room temperature.

Ultra-long-acting insulin degludec lasting up to 42 hours.

Basaglar

₹673

Manufacturer:: Eli Lilly
Strength:: 100 IU/mL
Forms:: Pen

Storage: Store at 2–8°C. Do not freeze. Once opened, use within 28 days.

Biosimilar insulin glargine with long-acting basal coverage.

Disclaimer: For informational purposes only; not medical guidance. Speak with your doctor for individualized recommendations.