Insulin is the one medicine we get asked about most in summer, and for good reason. Cuttack routinely crosses 40 °C in May and June, and insulin is a protein — heat does not just weaken it, it destroys it permanently. A pen that has been left in a hot room may look completely normal and still do nothing for your sugar levels.

The two temperatures that matter

Unopened insulin: 2–8 °C. That is the main body of a domestic fridge, not the freezer and not the door. The door swings between warm and cold every time someone opens it, and the freezer compartment can drop below zero. Insulin that has frozen must be thrown away, even after it thaws.

The pen or vial you are currently using: below 25 °C, up to 28 days. Once in use, most insulins can stay at room temperature for about four weeks — but “room temperature” means below 25 °C, which a Cuttack bedroom in June is not. Check the pack for your specific brand, because the in-use period varies.

What to do when the power goes

A closed fridge holds its temperature for several hours. Do not open it to check. If the cut is going to be long, move the insulin into an insulated flask or a small cooler with an ice pack — wrapped in a cloth so the insulin never touches the ice directly.

A clay pot with wet sand, or a wide-mouth flask, works well for the pen you are using day to day. It will not reach 2–8 °C, but it will comfortably keep you under 25 °C, which is all an in-use pen needs.

Travelling with insulin

Never put insulin in checked luggage on a flight — the hold gets cold enough to freeze it. Carry it in your hand baggage with the prescription. In a car, the glove box and the boot are the two worst places; both regularly cross 50 °C when parked.

How to tell if insulin has gone off

• Clear insulins (glargine, glulisine, lispro, aspart, regular) should be completely clear. Cloudiness, crystals or floating specks mean discard it.
• Cloudy insulins (NPH, premixed 30/70 and similar) should resuspend into an even, milky white after gentle rolling. If clumps stick to the glass or it stays patchy, discard it.
• Any brown or yellow tinge means discard it.

The hardest case is insulin that looks perfect but has been heat-damaged. The usual clue is that sugar readings creep up over a week or two with no change in diet — if that happens after a hot spell or a long power cut, a fresh pen is the first thing to try.

Write the date on the pen

The single most useful habit: the day you first use a pen, write the date on it with a marker. Nobody remembers four weeks later, and a pen that is quietly past its in-use window is a very common reason for unexplained high readings.

We keep insulin under cold chain at the shop and deliver it in an ice pack across Cuttack. If you are unsure whether a pen is still good, bring it in or send us a photo on WhatsApp — it takes a minute to check.

Written by Roshan Kumar Gupta, registered pharmacist (Reg. No. 38441/OPC, Odisha Pharmacy Council) and proprietor of Gupta Meds, CDA Sector 13, Cuttack.

This article is general information, not a substitute for a consultation. Always follow the advice of your own doctor or pharmacist for your specific situation.

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