Insulin Cooling Battles: Frio vs Gel

David Burren recently put me on to Breezy Packs which, if their claims are to be believed, offer a new way to keep insulin cool in the field. I have ordered a couple of Breezy Packs to put them through their paces but, first, I thought I would try out the existing methods commonly employed to show how they work.

Gel

Gel packs contain gel (no surprise there) which holds its temperature well and acts as an insulator. There is no actual cooling mechanism here other than the gel slows heat passing from one side to the other. So, to use a gel pack, you cool it down in the fridge (not the freezer as insulin does not like to be frozen) and put your insulin inside it to protect it from outside fluctuations in temperature. Outside heat is slow to heat up the gel pack which means the insulin stays cold.

Frio

Frio is, arguably, the most popular brand name for evaporative cooling pouches for keeping insulin cool. There are other brands out there (I even sell a version in my Etsy store) so feel free to shop around. They all work in the same way though. You immerse the pouch in water for, say, five minutes and it puffs up. You take it out of the water, wipe it down and put your insulin inside.

Not only are the pouch contents (generally silica gel beads or similar) an insulator but they are spectacular at absorbing and holding on to water. How Frio bags work is, when exposed to a warm temperature, the water in the beads begins to evaporate but evaporating water molecules takes energy so, instead of the external heat being used to raise the temperature of the water, some of it is used to turn the water to steam. This means the water temperature stays reasonably stable and, in turn, so does the temperature of the insulin inside the pouch. Our bodies use the same trick to stay cool when we sweat.

Breezy Packs

Breezy Packs offer a new way to keep insulin cool, which is similar to Frio bags but, instead of absorbing energy, turning water from liquid to a gas, it converts its active material from a solid to a liquid. No need to soak and wipe down. The physics of Breezy Packs is actually very smart so I will save it for when the pouches arrive and I will write another blog on the subject.

The Cooling Battleground: My Oven

It turns out that I can get my fan-forced oven down to around 30-40 degrees Celsius (104 degrees Fahrenheit) so this was my “controlled environment”. The contestants were a small Frio pouch capable of holding two insulin pens and a massive pillow gel insert.

The insert is 30x40cm with three panels. Both pouches went onto an oven tray with baking paper underneath to try and insulate from the metal bottom.

The gel pad was folded into three with two of the panels at the bottom and both pouches had a temperature probe put in the middle of them. As indicated above, the gel pad had been stored in the fridge whereas the Frio was soaked in tap water.

Once in the oven, I monitored their temperature and the temperature of the oven.

Here the gel pack is 10.7 degrees Celsius, the Frio pouch is 23.8 degrees Celsius, and the oven is 35.5 degrees celsius.

The Results

Thanks to the magic of Excel we can see how the two pouches fared. The oven temperature, which had previously reached the target temperature, was slowly dropping but remained above 30 degrees for the whole time. The Frio pouch, with the oven’s heat being used to turn the Frio’s water to steam, was holding a reasonably even temperature. The gel pouch, with nothing but insulation, slowly increased in temperature, catching up to the Frio after about 30 minutes, despite the 15 degree head start.

To be honest I was not sure the Frio pouch would work as well as it did as the oven was closed and, therefore, once the air inside the oven was saturated with moisture, the Frio would no longer be able to cool but for the 30 minutes it continued to work.

Conclusions

First of all I was really impressed the results came out as well as they did, showing the characteristics of the two pouches. For my money, if I was expecting to carry insulin for an extended period of time in high heat, I would likely look to a pouch that uses evaporative cooling. I would also invest in a MedAngel so I could check the temperature inside the pouch at any time and be alerted if things were going astray. Gel is a much cheaper option, of course, so, for short excursions, it will work fine. You could also, if you had a large enough pouch, put a cooled gel pouch inside a Frio pouch and gain a double benefit. As long as the Frio pouch is on the outside this should work fine.

EASD 2021: Reconciling the International Consensus Reports for LADA and Type 1. Part 2: Treatment

For Part 1, looking at reconciling the reports for diagnosis, go here.

Thanks to the generosity of #dedoc°, I recently had the privilege of virtually attending the world’s largest Diabetes conference: EASD 2021. Arguably the biggest news at the conference was an international consensus on the diagnosis, treatment, and management of Type 1 Diabetes. Interestingly, last year an international consensus was released for the diagnosis, treatment, and management of LADA. In Part 1 I reviewed how the two differed in terms of the diagnosis of Type 1 and LADA. In this second and final part I will look at the two reports’ recommendations for treatment and consider questions such as:

  • Should someone diagnosed with LADA go onto insulin immediately?
  • Are there treatments for Type 1 other than insulin?
  • If I do use insulin what are the pros and cons of the various methods of delivery?

As usual, for those who want the short version, you can go to the tl;dr section at the end.

Where We Landed In Part 1

In Part 1, I concluded the diagnosis flow chart from the Type 1 report was the more detailed and effectively covered LADAs flow chart.

So, assuming someone has LADA or Type 1 diabetes means either:

  • We have some reason to suspect diabetes (unintentional weight loss, ketoacidosis, glucose > 20 mmol/L (>360 mg/DL) etc.)

AND

  • Auto-antibody presence OR
  • Low C-peptide (less than 200 pmol/L (0.2 nmol/L) ) OR
  • No features of Type 2 diabetes (BMI >= 25 kg/m^2, no weight loss, no ketoacidosis, less severe hyperglycaemia etc.)

Treatment According to the LADA Report

The LADA report has a flow chart for treatment which looks like this:

The Type 1 C-peptide limit is different (0.2 nmol/L vs 0.3 nmol/L) but, given there are two other options available which do not consider the C-peptide level in the Type 1 report (auto-antibody presence and no Type 2 features), there is still the possibility that someone with Type 1 could have a C-peptide in any of the above three ranges.

I go through the LADA and Type 2 guidelines in detail in my “Gold Standard” LADA article. In short, if your C-peptide is over 0.7nmol/L (700 pmol/L) options include:

  • Metformin
  • GLP-1 RA
  • SGLT-2i
  • DPP-4i
  • Basal insulin
  • TZD

While part of the Type 2 algorithm, there is a notable exception of Sulfonylureas not being used with LADAs because “The panel concluded that sulfonylureas are not recommended for the treatment of LADA, as deterioration of b-cell function as a consequence of this treatment cannot be ruled out”.

For patients with a C-peptide below 0.7 nmol/L, there are two flow charts. The first is if heart (ASCVD/HF) or kidney (CKD) disease is present with the same medications as before except TZDs which may have been excluded because of the limited evidence of benefit and increased risk of bone fracture.

For patients without heart or kidney disease, we have this chart where the SUs are still not present but which does include TZDs.

What is good is this set of flow charts covers the entire Type 1 C-peptide spectrum which means, even when someone with LADA becomes a “classic” Type 1 because of declining C-peptide levels, we have a prescribed course of action. What is missing is a complete answer to the question “When should someone with LADA start using insulin?” The answer from the above flow charts is “If the HbA1c is above target” but no target is firmly established. Let us move to the Type 1 report.

Treatment According to the Type 1 Report

In fact, the Type 1 report immediately addresses the issue of targets for Type 1 in their first table.

Here the target HbA1c is 7.0% with the caveat that “all glycemic targets should be individualized and agreed with the person with diabetes.” So, unless we have discussed and agreed on a different target with our health care team, achieving an HbA1c equal to or below 7.0% is a good benchmark for considering moving to the use of insulin. This is in agreement in my post where I considered how high someone’s HbA1c could be before a significant risk of long term damage.

For the specific question of when someone with LADA should consider bolus insulin, we also have guidelines for post-prandial (after meal) insulin levels with the suggestion that 1-2 hours after a meal a person’s glucose level should be less than 10 mmol/L (180 mg/dL) and the option of pushing this to less than 7.8 mmol/L (140 mg/dL) if safe to do so.

In contrast to the LADA report, the Type 1 report takes an “insulin-first” approach saying “The cornerstone of type 1 diabetes
therapy is insulin replacement” and providing the following summary of the multi-pronged approach suggested for the newly diagnosed.

Given how difficult it can be to manage insulin therapy in the newly diagnosed, it acknowledges the need to prepare for hyperglycemia (“highs”) and hypoglycemia (“lows”).

The Type 1 report also talks about the relative merits for the different ways of delivering insulin.

Where money is no object, clearly, closed-loop technology is the winner.

Eventually (page 27 out of 37 pages), the Type 1 report talks about “Adjunctive therapies”. In other words, treatments which can be used alongside insulin.

There is common ground between the two reports with both reports mentioning Metformin, GLP-1 RA, and SGLT-2i. It also mentions pramlintide which is an amylin analogue (another hormone produced by the beta cells and, therefore, compromised in Type 1 diabetes). It fails to mention DPP4i and TZD. TZD may be because of the limited evidence but I am not sure why DDP4i’s were left off the list. They affect the same hormone cycle as GLP-1 RAs and therefore have similar effects/benefits.

Reconciling the Two Reports

In contrast to Part 1 where I sided with the Type 1 flow chart for diagnosis, here I am siding with the LADA report for treatment. There are a few reasons for this:

  • It explicitly considers treatment in the presence of heart and kidney disease
  • It offers a more comprehensive range of non-insulin treatment options e.g. DPP4i and TZD (but should likely include Pramlintide as well)
  • It takes the approach that insulin may not be necessary in patients with high C-peptide levels and, given the inherent hypo/hyper risk that comes with using insulin, if target ranges can be maintained, this seems like a sensible approach to me

This being said, the Type 1 report is much more comprehensive in considering the various ways of delivering insulin to the body (injection, pumps etc.) and also has a lot to say about looking beyond medication for individualised treatment e.g. considering lifestyle factors and diabetes education.

One big takeaway for all people with Type 1 or LADA should be that treatment no longer begins and ends with insulin. There are a range of other medications which can help with managing long term blood glucose levels and have other benefits such as helping a patient lose weight or reduce blood pressure.

tl;dr

Arguably, the LADA report’s flow charts for the treatment of Type 1 diabetes are more detailed for treatment than what is presented in the Type 1 report. Not only, does the LADA report consider insulin independence for patients with high C-peptide levels, it considers which medications are appropriate in the presence of heart or kidney disease. However, the Type 1 report fills in a significant gap of providing target values to chase and which help inform decisions such as when to move to insulin therapy.

The Type 1 report also goes into more detail in the areas of:

  • The relative merits and costs of different insulin delivery methods
  • Treatment of Type 1 diabetes beyond medication e.g. lifestyle factors and education