The Practical Diabetic

My last cooling battle was about four years ago, comparing Frio with BreezyPacks’ Breezy Basic. With a new product on the market, InsulinSaver’s “The Bag”, I thought I would see how the products stack up. To better understand how the BreezyPacks and InsulinSaver bags resist the heating of the insulin pens, check out that last cooling battle link where I explain the role of PCMs and how they work similarly to the Frio but without the soaking.

Disclosures

In the battle, I will be evaluating three cooling bags:

• Breezy Basic
• The Bag
• Breezy Extra

I also have a BreezyPacks bag called the “Breezy Plus” which is the same size as the Basic but with more active material. However, this is no longer on sale at BreezyPacks so I have excluded it from the comparison.

The Breezy Basic (and Plus) I bought at full price online and I bought The Bag at full price while at ATTD2025. I informed BreezyPacks of my intention to do a comparison and I asked if they had data on the Extra or would be willing to provide one for the comparison and they generously sent me one.

Neither BreezyPacks or InsulinSaver are paying me to do this comparison or offering any other incentive.

Comparing the Bags

	Website Price (ex. Tax/Shipping)	Capacity (Insulin Pens)	Weight	Max. Temp (C)
Breezy Basic	US$33.90	3	176g	41
The Bag	US$41.96 (36.90 Euros)	6	368g	54
Breezy Extra	US$43.90	10	267g	46

In terms of price, the pricing scales with capacity. For shipping to Australia, Breezy is about US$7 and for InsulinSaver it is about US$14.

The weight is a rough indicator of PCM material being used (the substance that resists the change in internal temperature) and we can see The Bag has the most, but it should be noted, we do not know InsulinSaver and BreezyPacks are using the same material. I also weighed my Breezy Plus which came in at 25.1g, similar to the Breezy Extra.

The Bag is also rated for a higher temperature than the Breezys but all fit within the range of most temperatures the bags are likely to be exposed to under normal conditions.

Measuring the Changes in Temperature

To measure the change in temperature, I used my oven on the lowest temperature setting. On the dial this is 50C but, as measured at the end of the experiment, the oven temperature was closer to 36C. This is within the limits of the bags and equivalent to hot summer day here in Sydney, Australia.

As you can see above, the three temperature sensors I used are all measuring the same temperature (this was at the end of the experiment, outside of their bags), within half a degree of each other (about a degree in Fahrenheit).

To replicate the conditions of an insulin pen as closely as possible, I put the probes inside NovoRapid insulin pen containers, retaining the empty glass reservoir inside.

These were then placed in the three bags being tested, one pen per bag.

Finally, these were placed in the oven on the same rack with the fan force function operating to try and maintain as even a temperature as possible.

It was then a case of recording the temperature every 15 minutes until the bags went over 30C or until three hours had passed, whichever came first.

The Results

This result genuinely surprised me. With the additional active material, I expected The Bag temperature to stay flat, relative to the others, but it closely trailed the Breezy Basic. In the final 15 minutes, the Breezy Basic started rising while The Bag was stable and I suspect this was due to all of the active material being liquified and no longer providing protection. Certainly, giving each bag the ‘squeeze test’, the Breezy Basic was almost fully liquefied, the Breezy Extra less so but still containing a fair amount of liquid PCM while The Bag felt almost completely solid. This is either a function of the larger amount of material or confirms InsulinSaver uses a different PCM to BreezyPacks.

I have a hypothesis why the Breezy Basic and The Bag performed similarly while the Breezy Extra heated up quicker and it has to do with the cross-sectional/exposed areas.

The sides of the bags are full of active material, but the ends are not. We can also see the cross-sectional area of the Breezy Extra is about double of The Bag (the top part of the Breezy Extra is also largely unprotected). With possibly less active material than The Bag and a larger unprotected area, this meant the Breezy Extra heated up quicker as the heat came through the unprotected areas. With the smallest cross-section, the Breezy Basic was the best protected from this attack and, even though The Bag’s end area was bigger, this may have been offset by the protection of the additional material on the sides. Ultimately though, after three hours, the Breezy Basic ran out of active material and the temperature started going up.

The good news is, even at these high temperatures/extreme conditions, the Breezy Extra lasted over an hour (and did not go past 31C for three hours), and the other two lasted over three hours.

Conclusions

For the ability to protect, and pen capacity, it is hard to go past The Bag but all three are robust at protecting their contents. For two-week trips, like the one I just did to Europe and the USA, I can see The Bag being used for my backup insulin pens and the Breezy Basic being used for the Fiasp penfills I use to refill my pump. If I need more capacity (or need a bag with a handle) the Breezy Extra is also a great option. I can see myself using the Breezy Extra as a standalone bag with refills, pump sets, backup pens etc. for overnight trips, a bag for work, or day trips.