Insulin and GLP-1 pens in Barbados heat: what labels and studies say

Why storage matters for peptide drugs in Barbados

Insulin, semaglutide and tirzepatide are peptide medicines, and heat and freezing are their enemies. In Barbados they are central to diabetes care: the national Health of the Nation survey found diabetes in 18.7% of adults aged 25 and over¹², and the Barbados Drug Service lists insulins on the Barbados National Drug Formulary, paying for up to two pens per client per month for each therapeutic class under a protocol announced in April 2024¹⁰. Prime Minister Mia Mottley has also said the government is committed to putting weight-loss medication on the formulary¹⁴. More pens in more homes means storage becomes a clinical question.

What the product labels say

The European product information for Ozempic (semaglutide) says to store pens in a refrigerator at 2–8 °C, "Keep away from the cooling element" and "Do not freeze Ozempic"². After first opening, the in-use shelf life is 6 weeks for 4-dose pens and 8 weeks for 8-dose pens: "Store below 30 °C or in a refrigerator (2 °C–8 °C)"². For Mounjaro (tirzepatide), single-dose pens and vials "can be stored unrefrigerated for up to 21 cumulative days at a temperature below 30 ºC" and must then be discarded; the multi-dose KwikPen can be kept below 30 °C and must be discarded 30 days after first use³.

For insulin, the FDA says vials and cartridges "may be left unrefrigerated at a temperature between 59°F and 86°F for up to 28 days" (15–30 °C)⁴. The common ceiling across these labels, 30 °C, is the same as Barbados' long-term average daily maximum at the airport: 30 °C over 1981–2010, with 30.6 °C in August and a record monthly average of 32 °C in September 2005¹. Those are standard weather-station readings, not the temperature inside a car or a closed house.

What the studies show about heat and home storage

The evidence on insulin is more reassuring than the labels suggest. A study in PLOS ONE recorded temperatures in a Kenyan refugee camp that oscillated between 25 and 37 °C, reproduced them in the lab and tested several commercial insulins weekly: potency stayed within pharmacopoeia limits over four weeks, and the authors concluded that insulin can be kept at such temperatures for the usual four-week period of use⁵. The study did not test semaglutide or tirzepatide.

Refrigerators are not a guarantee either. In a study of 338 people with diabetes who placed Bluetooth sensors next to their insulin, every refrigerated log (100%) showed deviations; refrigerated insulin was out of range 11.3% of the time, on average 2 hours 43 minutes a day, and 17% of sensors recorded temperatures below 0 °C⁶. For drugs whose labels say "Do not freeze"²³, a cold fridge can be as much of a problem as a hot room.

Power cuts and hurricanes in Barbados

Barbados has seen both. On 4 April 2023, a flash-over at the Spring Garden plant caused an island-wide outage; the Barbados Light & Power Company restored all customers by 5:17 p.m.⁷. In September 2023, a fault on a 24kV transmission line in St Thomas "caused the system to cascade", forcing schools and public offices to close⁸. On 1 July 2024, Hurricane Beryl brought a storm surge: CBC reported at least two pleasure craft and about 20 fishing vessels lost and, according to preliminary reports, about 40 houses damaged, although Prime Minister Mottley said Barbados "evaded the worse of Hurricane Beryl"⁹.

Experience elsewhere shows what a direct hit means. After hurricanes Harvey, Irma and Maria in 2017, diabetes specialists had to set up "insulin supply lifelines" and share insulins and supplies across sites for people with type 1 diabetes¹³. The FDA's emergency guidance says insulin stored above 86 °F (30 °C) may have to be used, but should be kept as cool as possible and replaced once properly stored insulin is available; frozen insulin should not be used; and any switch between insulins should happen under a doctor's care with close glucose monitoring⁴.

Points physicians in Barbados can raise

Based on these sources, physicians can ask patients where they keep pens, check that in-use pens are within their label limits²³⁴, warn about freezing at the back of the fridge⁶, and include peptide medicines in hurricane-season planning⁴¹³. Barbadian patients may also need reassurance about injections themselves: in the Barbados Insulin Matters study, 58% of people with type 2 diabetes feared self-injection¹¹.