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When the hottest days of the year arrive, how do people with diabetes best keep their insulin cool so that it doesn’t go bad in the heat?

Whether you’re wearing an insulin pump filled with this life-sustaining medication or carrying around an insulin pen or glass vial, it’s critical to think about protecting insulin in the summer heat.

Severe storms and power outages can also present temperature concerns, making insulin coolers a critical tool to have on hand to ensure that this precious medication remains effective.

We’ve taken a close look at some of the most well-known insulin cooling products to help address this problem.

The Frio cooling wallets have been around since the late 1990s, and are arguably the most popular option. They are light, simple, compact, and easy to use. They are soft wallets that use evaporative water cooling to keep insulin in the sub-80 range for 48 hours, even when the outside temps are well above 100°F (38°C).

All you do is soak the cooling insert in water for 5 minutes before placing it back in the wallet cover, and it’s ready to use.

To reuse, you just soak the inner sleeve in water again and you’re good to go. Frios have the advantage of working in reverse, too, protecting insulin from getting too cold in freezing weather.

They come in a variety of sizes: from single wallets to carry one or two insulin pens, to larger, wider wallets that can hold multiple pens or glass vials and syringes. There’s also a wallet designed specifically to keep an insulin pump cool. This Frio size guide can help in the decision-making on which model is best for your needs. You can find these in various colors and some patterned designs, too.

Additionally, there are small Frio liners you can buy that can keep insulin pens, pumps, or supplies protected from water.

Frio cooling wallets range from $22 to $35 on the Frio website, or on Amazon.

Medicool cases have been around for quite a while as well, dating back to the 1980s. This company specializes in a wide range of insulated coolers with a molded insert that needs to be frozen, then re-frozen to be used again. It’s a step up from an ice bag, at least in terms of being less messy, but refreezing takes time.

They come in blue and black, generally rectangular shaped with an outside zipper. Some people like the hard cases because they are protective. But some of their larger Dia-Pak cases have a gel pack inside, which could be an issue if you travel and go through a TSA security check where a gel pack is flagged for inspection.

They also make smaller cooling pouches that are basically knockoffs of the Frio wallets, using the same water evaporation method to keep the insulin cool. These also come in various sizes and colors.

Depending on the case, you can also get a pocket or pouch inside to store other supplies like insulin syringes, a fingerstick glucose meter, and test strips.

Prices range from $20 to $30, sold at their website, Amazon, and various online diabetes supply sites.

Owned by the parent company Group Medical Supply that’s been making diabetes carrying cases since the mid-2000s, these ChillMed cases first launched in 2012.

The company makes a variety of diabetes carrying cases in different sizes and styles, including two styles with a built-in cooling element.

The ChillMed Go-To Medication Cooler is a small rectangular case available in red, blue, and gray. It comes with a re-freezable 3-ounce gel pack that offers up to 3 to 4 hours of cold time.

The ChillMed Micro Cooler is also a small rectangular case that comes in the same colors. But this one comes with a molded ice brick that fits two insulin vials or two pens, and offers up to 12 hours of cooling time.

Both bags have mesh pockets for syringes, medical wipes, and other small supplies

Prices range from about $20 to $22 for the bags, and about $9 for a replacement ice brick or gel pack, available at Walmart, Amazon and many diabetes supply sites on the web.

A newer trend in insulin temp control is the use of stainless thermos technology such as the Insulin Safe and its cousins, which can be found on Amazon, eBay, and Aliexpress/Alibaba.

One strong option, although pricey, is the 4AllFamily thermos cooler, which launched in 2019 and can store insulin safely for 72 hours. It actually uses three different cooling methods: You can switch the lids to go from a Biogel freeze pack to a USB-powered portable medicine fridge. Or you can use both simultaneously for maximum effect, keeping insulin at refrigerator temperature at or below 40°F (4°C) for up to 4 days.

With a large storage capacity (3.3-inch diameter and 900-milliliter total volume), this cooling case can fit up to 7 insulin pens, 42 Humulin vials, or 8 Novolog vials. At $140 a pop, it really is an investment for the whole family if needed.

On the budget end, there’s the much more affordable CaseMD product that is becoming popular in the diabetes community. Designed by physicians, it’s a compact vacuum-insulated container made of double wall stainless steel with vacuum insulation to guard against damaging heat or cold, humidity and UV light. It uses patented Thermashield technology to provide “ultimate temperature regulation to protect your sensitive medications.” These come in a regular and XL size designed to fit most injection pens, for $33 to $40.

Overall, insulin thermos products range anywhere from the low $30 range to upwards of $130 or more depending on the materials they’re made of. Find them on Amazon and a variety diabetes supply sites.

Unlike most of the above-mentioned products, TempraMed Vivi caps are specifically designed to keep a single insulin pen cool and protected.

What you do is use the Vivi cap to replace the cap on your disposable insulin pens, and the cap will keep your insulin at steady temps for years on end without electricity, water, battery charging, or refrigeration.

This magic is achieved using “cutting edge space grade insulation [that] is used in spacecraft, avionics, cryotherapy, and other demanding applications,” according to the manufacturer. “The heat absorbing activity is guaranteed to perform every day for years on end without requiring any user intervention. The monitoring electronics provides intuitive indication of the temperature of the medication.”

It starts working at around 84°F (29°C) and holds the insulin at 82°F (28°C). They also have a “coming soon” version for insulin vials, according to the TempraMed website, in August 2021.

This higher-tech product is on the pricier end at $95, available directly from Isreal-based TempraMed.

How hot is too hot? How long insulin can beat the heat?

The three major injectable insulin makers — Eli Lilly, Novo Nordisk, and Sanofi — told DiabetesMine that refrigeration temperatures between 36°F (2°C) and 46°F (8°C) are maintained for insulin products during the manufacturing process, and that remains the recommended range.

Read our in-depth coverage on insulin in the summer heat here.

Ice packs were the traditional solution. But while ice packs are great for post-surgical swelling, they’re not effective in keeping insulin cool. The ice melts quickly, they’re messy, and they actually keep insulin cooler than it needs to be, at least for insulin you’ve already opened and are using.

Also, it’s important that the ice not have direct contact with the insulin glass vial or the plastic insulin pen, as it could freeze the insulin, which also renders it ineffective immediately. For this reason, the insulin makers warn strongly against putting insulin in the freezer, or directly adjacent to the refrigerator cooling element.

Insulin itself is a pricey and life-sustaining liquid that needs protection, especially during the hotter months of the year and in case of disasters like a stronger storm or longer-term power outages. So, it’s a really good idea to investing in a trustworthy insulin cooling case — ideally one that doesn’t require melting ice or regular recharging. Fortunately, you have an array of styles, colors, sizes and cooling methods to choose from.