Storing insulin in Indian heat: home, power cuts and travel

Insulin is a protein, a bit like egg white. Too much heat or freezing can damage it, and damaged insulin works less well, so your sugars may rise without any obvious reason. In much of India, summer temperatures go well above 40°C, power cuts are common and long journeys are part of life. A few simple habits protect your insulin.

How should I store unopened insulin?

Keep spare, unopened pens, cartridges and vials in the refrigerator at 2 to 8°C. A middle shelf, away from the cooling plate or back wall, is usually best, because insulin there is less likely to freeze and the temperature swings less than in the door.

• Never put insulin in the freezer, or against the back wall or the cooling plate of the fridge, where it can freeze.
• Keep it in its box, which protects it from light.
• Unopened insulin kept this way lasts until the expiry date on the pack.

Insulin that has been frozen should not be used, even after it thaws.

What about the pen or vial I am using?

Once you start using a pen or vial, most insulins can be kept at room temperature below about 30°C for a limited time, commonly around 28 days, after which the rest should be thrown away. Some products allow a shorter or longer period, so check the leaflet that comes with your insulin. Many people find cold insulin stings more, which is another reason in-use insulin is often kept out of the fridge.

The problem in India is that “room temperature” in May or June may be far above 30°C. In hot weather:

• keep in-use insulin in the coolest part of the home, away from windows, the kitchen stove, the top of the fridge and any direct sunlight
• if your room regularly gets hotter than about 30°C, ask your doctor or pharmacist whether to keep in-use insulin in the fridge, and let it warm in your hand for a few minutes before injecting
• do not leave insulin on a sunny windowsill, a two-wheeler seat, or in a parked car, which can become extremely hot within minutes

A pen should be stored without the needle attached, so that air and insulin do not leak in or out.

What if there is a power cut or I have no fridge?

Short power cuts are not a concern. A closed fridge stays cool for several hours. For longer outages, or if you do not have a fridge:

• use a commercial insulin cooling pouch or wallet, many of which work by evaporation when soaked in water, or an insulated box
• traditional earthen pots (matkas) with water can keep insulin cooler than the room. A small study found that clay pots lowered storage temperatures in hot climates.
• do not put insulin directly on ice, which can freeze it

A laboratory study that copied the swinging day and night temperatures of a hot refugee camp, between about 25 and 37°C, found that common insulins stayed stable over a four-week period of use. This is reassuring if your insulin was briefly warm, but it does not mean insulin can be left in very high heat. Follow the storage advice on your pack.

How do I travel with insulin?

• Carry insulin in your hand luggage on flights, never in checked baggage, where it may freeze or be lost.
• Carry a doctor’s letter or prescription listing your insulin and devices, especially for air travel and international trips.
• Use an insulated pouch on trains, buses and road trips, and keep it out of direct sun.
• Take extra supplies, needles, a glucometer and fast-acting sugar for lows. Read starting insulin: what to expect.
• When crossing time zones, ask your doctor in advance how to plan injection timings.

If you use a pump, the insulin in the reservoir is close to your body heat and is usually changed more often. Read insulin pumps and automated insulin delivery. CGM sensors have their own storage temperatures on the pack too. Read CGM sensors in India.

How can I tell if insulin has been damaged?

Damaged insulin may look normal, so the best clue is often unexplained high sugars. Check the insulin before each use:

• Clear insulins (such as most rapid-acting and long-acting ones) should look clear like water. Do not use them if they look cloudy or have particles.
• Cloudy insulins (such as NPH and many premixed insulins) should turn evenly milky after gentle rolling. Do not use them if there are clumps, white crystals stuck to the glass or a frosted look.
• Do not use insulin past its expiry date or past the in-use period after opening.

If you suspect your insulin has been damaged, start a new pen or vial from the fridge, and tell your doctor if your sugars stay high.

What should I ask my doctor or pharmacist?

• How long can my particular insulin stay out of the fridge once opened?
• Should I keep my in-use insulin in the fridge in summer?
• What should I carry when I travel?
• What do I do if I run out or my insulin is damaged?

For help with your insulin plan, book a consultation.