If you have seen the Glucology or Frio insulin pouches you will already understand the concept of an evaporative cooling insulin pouch. They work really well but the downside is the price. For a two-pen pouch you are looking at around US$30. In this blog I will show you how to make your own for less than US$5 (if you have a sewing machine) or, if that is too much hassle, you can buy a ready-made one from my Etsy shop for around US$20 including shipping anywhere in the world or AU$25 including shipping within Australia. For every one purchased, I will be supplying an identical one to charities around the world who are supplying insulin in developing countries where refrigeration is unreliable.

How Do They Work?

Evaporative cooling pouches work off of the idea that if water is evaporating from something, that something gets cooler. This is how humans cool themselves i.e. sweating. The key technology in the cooling pouches that allow them to remain cool for well over 24 hours are the little beads inside the pouch. These hydrophilic beads (a big word meaning they hold onto water) are the same ones you might know as Orbeez or those squishy spheres you see flowers in sometimes.

Same technology, different application. While the beads love holding onto water, it still evaporates and, while it does, they and anything they are surrounding feels cool to the touch. Embed them in material and that material, and anything it is surrounding also becomes cool.

DIY Step One: The Materials

Firstly, you will need two cooling scarves. They look like this:

You can buy these from Amazon but this will set you back about US$4 each before postage. Go to Ebay and select the international option and, while it might take a little longer to arrive, you can pick them up for around US$1 each.

You will also need a sewing machine or someone with the time to hand stitch them.

DIY Step Two: Stitching

Lay one on top of the other. For symmetry, I have put the seam of one (the white stitching on the edge) to the non-seam side of the other.

Then you will want to do a straight stitch along the edges so the two pieces form a long tube.

The dark line at the bottom on the scarf in the above picture is the straight stitch you need to do on the top and bottom. There is one at the top in the image as well but, because I was using a light brown thread in my bobbin, it is a little tricky to see. While I went a little over in the above picture, you want to go up to the white stitching which runs up and down on the left hand side in the above picture. This gives you the ties on the end of the scarf to secure the pouch, once finished.

DIY Step Three: Inverting

Arguably the fiddly bit, you now push the tube inside of itself to invert it and hide the stitching. I found the best way was to pull it out, rather than trying to push it through with a stick. In the end you will have an inverted tube which looks something like this.

You are now the proud owner of a cooling insulin pouch. Well done!

How To Use Your Pouch

Before use you will need to soak your pouch. I recommend no more than five minutes. Any more than this and the beads will absorb too much water and make it too hard to insert the pens/cartridges/vials. There is probably a risk of splitting the stitches as well.

Once soaked, dry it off with a dishcloth or towel. The material does not have to be wet for it to be effective. It is the beads inside which do the work.

Then, you can insert your hardware.

In the above example, I have my basal and bolus insulin pens and a MedAngel (a Bluetooth thermometer which connects to your phone).

Once inside, you can use the those end ties to keep it all together.

Does It Really Work?

While I am still insulin independent, I always carry insulin whenever I travel overseas for work. Just before the world locked down, I took my pouch to Singapore. Even with Singapore’s humidity, the pouch, within my backpack, was effective at keeping my insulin cool as I walked, in the direct sun, to the office each morning. Tests I have conducted in more controlled conditions show the pouch is as effective as its commercial counterparts.

Here you see three temperature gauges measuring (in Celsius) the temperature in my house (the middle one), the temperature of a commercial pouch (on the left) and my one (on the right). Even inside, both pouches shaved off 2-3 degrees Celsius (4-6 degrees Fahrenheit). The effect becomes even stronger in direct sunlight where I have seen temperature differences of 10 degrees Celsius (20 degrees Fahrenheit) between the ambient temperature and the pouch.

“Recharging”, Storage and Care

The pouch will continue to keep the contents cool for over 24 hours. When you want to “recharge” it, immerse it in water for no more than two minutes. Again, if you over-immerse, you risk expanding the beads too much and making it impossible to insert your pens etc. or breaking the stitching.

If you are not planning on using your pouch for a while, let it completely dry out in the sun or on an air vent and, when completely dry, store it in a cool, dry place.

Most diabetics, certainly most Type 1s, know their HbA1c. As described previously, the HbA1c is a measure of the ‘average sugariness’ of the blood over the last three months. As a diagnostic test, the HbA1c has been with us for a little over 40 years and has served us well. However, as technology has improved for the management of diabetes, the ways we keep tabs on our blood has also evolved and a new measure: Time in Range is growing in popularity among both diabetics and researchers alike. In fact, quite a few talks at EASD 2020 spoke directly at Time in Range and linked it to the long term health of diabetics.

In this blog I will talk about what the HbA1c tells us, its limitations, and the additional insights we can gain through the Time in Range. As usual, at the end, we have the ‘Cliff Notes’ tl;dr.

Benefits of Measuring the HbA1c

As I have shown previously, many papers examine the relationship between long term HbA1c and complications and this was reiterated by Professor Pratik Choudhary at EASD 2020 with this excellent graph.

The Limitations of the HbA1c

While of diagnostic value, there are limitations with the HbA1c measure.

Firstly, the measure assumes the lifespan of the red blood cells as part of the calculation so, if this assumption is invalid, it can affect the HbA1c. Common causes of false HbA1c readings include:

• Anaemia
• Excessive alcohol consumption
• Excessive use of opiates
• Pregnancy
• Blood transfusions

The second and arguably biggest limitation of the HbA1c measure is while it speaks to the ‘average sugariness’ it says nothing of the variation. This is why, historically, doctors have erred on the side of a higher HbA1c with Type 1s, often to the diabetic’s frustration. The reason is simple: if the diabetic’s glucose levels fluctuate significantly, and they keep a lower glucose level, they are at an increased risk of hypo whose effects are immediate (groggy, fall over, go unconscious etc.) whereas running a little ‘high’ and fluctuating mitigates the risk of hypos at the expense of increasing the risk of long term nerve damage. To put it simply, with limited visibility of the fluctuations using strip glucose monitors, it makes sense that doctors err to minimize risk today and encourage their patients to run a little higher with a view that the longer term risks can be managed later.

Interestingly, in his talk, Professor Choudhary blamed his patients for running high and having high fluctuations, suggesting they are driven by fear of a hypo which then leads to over-correcting and large fluctuations.

Fortunately, Continuous Glucose Monitoring (CGM) technology gives a much clearer picture of the fluctuations, informing both the doctor and patient, and allowing them to proceed informed, rather than out of fear.

Time in Range

It has taken a while for a standardization of Time in Range guidelines but in August 2019 we got one from the ADA.

The standard is adjusted for various sub-groups of diabetics.

What is more, these ranges are not random, or at the whim of some group of doctors, but backed up by statistically significant links to both long term complications and the equivalent HbA1c.

Some of these were highlighted by Professor Richard M. Bergenstal.

and Anass El Malahi at EASD 2020.

As we can see, we can link changes in Time in Range to changes in the risk of retinopathy, microalbuminuria, microvascular complication, and nephropathy.

Professor Bergental also showed, using the CGM data of three of his patients, how much more insightful Time in Range can be, compared to HbA1c.

Here the three patients have exactly the same HbA1c but very different experiences with their diabetes. with the third patient spending a lot more time in hypo and much less time in range.

Bringing together the Time in Range with the latest data on what it means for long term complications, the Ambulatory Glucose Profile (AGP) Report captures the key metrics along with statistically significant guidelines in one page.

As we can see the report captures:

• Percentage time in the different BGL ranges
• Average Glucose
• Glucose Management Indicator (GMI): an estimation of the HbA1c
• Glucose variability: a measure of fluctuation

which, given the GMI on its own is a proxy for the HbA1c, shows we are considering a lot more information in the AGP report than simply ‘average sugariness’.

The Big Problem with Time in Range

The big problem with Time in Range analysis is it requires a Continuous Glucose Monitor (CGM) to capture the data: it is a metric of privilege. While many of us have no exposure to it in the West, in places like Mexico, some Type 1 diabetics are given literally one strip per day to manage their blood glucose levels. Fortunately, research shows the proportion of finger pricks in, below or above range can still be correlated to HbA1c estimations and, therefore, give an indication of long term risk.

Also, with an increase in Time in Range of 10% leading to a lowering of HbA1c of 0.5%, using the above, we see that for someone whose finger pricks are in range 70% of the time, this correlates to an HbA1c of roughly 7%, as with the CGM data. This means the AGP Report and the guidelines it contains can be applied to CGM or finger pricking equally. So, while a diabetic’s management technology may change over time, their reporting for their health care team does not have to.

tl;dr

With the advent of Continuous Glucose Monitoring (CGM) we have new and insightful ways of examining our data beyond what is available with finger pricking and the HbA1c. One such way is analysing the Time in Range of our data. Time in Range provides a wealth of knowledge about both average sugariness and the glucose level fluctuations. One way to present this information is with an Ambulatory Glucose Profile (AGP) Report.

While driven by CGM technology, it is possible to use the AGP Report with finger pricking by considering the proportion of results that fit in the low medium or high categories. This now means we have a common report whether we are finger pricking or using CGMs.

Clinical research using Time in Range analysis has also established that it is predictive for a range of long term diabetes complications. This means, Time in Range analysis and the AGP Report are now a viable alternative to the HbA1c and provide much richer insights.

I first read about incretin mimetics in Dr. Bernstein’s fourth edition of “Dr. Bernstein’s Diabetes Solution” published in 2011. He devotes nine pages to this class of drugs and it is a good place as any to describe what they do. It should be noted for those unfamiliar with Dr. Bernstein, his focus is on the treatment of Type 1 diabetes. While incretin mimetics are sometimes hailed as a ‘Type 2 drug’, they can be of benefit to diabetics of all Types as I will show in this blog.

From there I will update the information based on some peer reviewed papers from recent years (specifically relating to LADA) and the presentations at the recent EASD 2020 conference and then onto my own experience using them. As usual, there is the tl;dr at the end if you want the short version.

What Are Incretin Mimetics?

To understand the role of incretin mimetics, it is important to understand that beta cells produce, not just insulin, but also another hormone called amylin. Amylin is a ‘satiety’ hormone i.e. it makes you feel full. So, as the beta cells become damaged they are less able to produce this hormone. Amylin is released in response to the presence of ‘gut hormones’ in the blood, released when the gut is stretched. These ‘gut hormones’ are called ‘incretins’.

Based on all this, Dr. Bernstein suggests that diabetics of all persuasions are likely to not feel as ‘full’ as their non-diabetic counterparts. For me, this poses the question: “If someone who has impaired beta cell function cannot effectively regulate their eating, is it possible Type 2 diabetes and pre-diabetes causes obesity and not the other way around?” but that is a blog for another day.

At the time of writing his book, Dr. Bernstein describes incretin mimetics as being used to lower blood sugar levels after meals and for weight loss. We now know they have many more effects on the human body.

GLP-1 Receptor Agonists (GLP-1RAs) are one such incretin mimetic. As per the above we see, among other things, they can:

• Lead to weight loss (likely due to the increased sensitivity to feeling full)
• Lower glucagon secretion (meaning the liver releases less glucose into the blood)
• Stimulate insulin secretion and production (to process the food that is causing the stomach to feel full)
• Decrease beta cell apoptosis (this is the fancy name for programmed cell death. Cells in the body are given a countdown clock. When that clock reaches zero the cell destroys itself. Incretin mimetics tinker with that clock to extend the life of beta cells)
• Offer protection from heart disease
• Lower blood pressure

I should note that while these drugs do stimulate insulin production like, say, sulfonylureas unlike ‘sulfs’ the evidence shows this does not accelerate the demise of the diabetic’s honeymoon. My guess is the suppression of apoptosis counters the effect. Another possible explanation is, because the insulin is getting triggered earlier and harder, the blood sugars are not getting the opportunity to rise as high. Dr. Bernstein talks about how it takes more insulin to bring blood sugar down by a fixed amount when it is at a high level than when it is lower. So, the mimetics get the insulin out early when it is more effective and therefore the net production for a given meal is less.

Types of Incretin Mimetics

There are three types of incretin mimetics. These are:

• Amylin analogs: To my knowledge the only one on the market is Symlin (pramlintide). This is available by injection. I have not tried this one. EASD 2020 had a presentation on using it in a dual-hormone therapy (pumps with insulin and pramlintide) but the benefit of the additional pramlintide, in this context, was minimal.
• GLP-1 agonists (mentioned above): This is mentioned above with the associated effects. Until recently this was also only available via injection. Recently an oral version has been released (more of that later). I am currently on a once-weekly injection of this drug. Here are the six GLP-1s on the market at the time of writing.

• DPP-4 inhibitors: DPP-4s destroy GLP-1s in the body so this drug opposes that destruction and therefore, in principle, eliminates the need to inject GLP-1s. DPP-4s are available in an oral form and I took these for at least six months before moving to the GLP-1 agonists.

Contraindications and Side Effects

I will list some of the more common side effects but this list, like for most drugs, is far from exhaustive so discuss your specific history with your health care team to get a full picture of how well these drugs might suit your circumstances and complication risk profile.

Firstly, incretin mimetics slow stomach emptying so this can make gastroparesis (a condition not uncommon in Type 1s) worse. This slowing can also induce nausea. People on social media will be more than willing to tell you how incretin mimetics made them violently ill. For me, I feel mild nausea a day after injecting the GLP-1 agonist (akin to very mild car sickness) but felt no such effect when taking the DPP-4 inhibitors.

One side effect that was actually beneficial for me was constipation. As I also take Metformin, I have found the GLP-1 agonist and Metformin balance themselves out nicely giving me a lot of freedom I did not have when taking Metformin with the DPP-4 inhibitor. It is different for everyone though as GLP-1 agonists are also reported to have diarrhoea as a side effect.

One of the more serious side effects is the risk of reversible pancreatitis. I am informed pancreatitis is one of the most painful things you can experience and is usually characterized as a sudden, severe abdominal pain extending through the body from the back to the front. As the name suggests, stopping the medication reverses the condition.

LADA-Related Studies on DPP-4 Inhibitors

Given I am a Type 1 LADA trying to preserve my beta cells as long as possible and avoid the financial and mental stresses of insulin management, many of the studies I have earmarked, up to EASD 2020, are focussed on blood glucose management and beta cells preservation. Here are a few:

• Investigating optimal β-cell-preserving treatment in latent autoimmune diabetes in adults: Results from a 21-month randomized trial : n = 64 GAD-positive insulin-independent Type 1s. Insulin vs a DPP-4 inhibitor over 21 months. It was found that for patients with low GAD levels, both approaches preserved beta cell mass.
• Dipeptidyl Peptidase 4 Inhibitor Sitagliptin Maintains β-Cell Function in Patients With Recent-Onset Latent Autoimmune Diabetes in Adults: One Year Prospective Study : n = 30 LADAs. Half received insulin only and the other half received insulin and a DPP-4 inhibitor. Those who received the combined therapy produced similar levels of c-peptide as at the start of the study, compared to the insulin-only group who had significantly reduced c-peptide levels.
• Saxagliptin improves glycaemic control and C-peptide secretion in latent autoimmune diabetes in adults (LADA) : n = 2,709 GAD positive and negative diabetics (what I will call LADAs and Type 2s). Placebo controlled trial studying a DPP-4 inhibitor over 24 months. HbA1cs were reduced in both groups, LADAs had a reduction in fasting glucose and post-prandial glucose levels, beta cell function improved for both groups.
• Management of Latent Autoimmune Diabetes in Adults: A Consensus Statement From an International Expert Panel : Presents a flow chart for the treatment of LADA, depending on c-peptide levels. For high c-peptide levels, insulin is not recommended but a modified version of the Type 2 ADA/EASD guidelines are recommended which includes both DPP-4 inhibitors and GLP-1 agonists.

Presentations From EASD 2020

Tina Vilsbøll presented on Semaglutide, a new GLP-1 which can be taken as a once-weekly injection or as a once-daily oral pill, both being equally effective.

Juris Meier went into more detail as to the efficacy of the oral version, compared to other GLP-1 agonists, in Type 2s, showing it was more effective at reducing HbA1c.

The oral version of Semaglutide also compared favourably to the DPP-4 inhibitor Sitagliptin at doses above 3mg for Hba1c reduction and weight loss.

The downside was an increase in adverse reactions at the higher doses, compared to Sitagliptin.

So, if you are considering swapping out Sitagliptin for Semaglutide, understand that for a superior effect on HbA1c and weight loss you are also at a greater risk of those adverse effects.

Alice Cheng showed how the injectable version compared favorably to both DPP-4 inhibitors and other GLP-1 agonists for reducing HbA1c and weight loss.

For adverse effects, Semaglutide was comparable to other GLP-1 agonists.

My Experiences With DPP-4 Inhibitors and GLP-1 Agonists

As mentioned, I have used both in an attempt to preserve my beta cell mass. For me, the DPP-4 Inhibitor had no side effects or, at least, any side effects were washed out by the ones from Metformin. The DPP-4 Inhibitor did nothing for me in terms of HbA1c reduction (although it is already in the mid-5% for this is not surprising), satiety, or weight reduction.

My experience with the injected GLP-1 agonists has been very different. Given the trouble I was having with Metformin, I halved that dosage but found the two drugs balanced each other nicely, as touched on before. I have lost five kilograms over a couple of months (I have it to lose) which I attribute to my significantly reduced appetite and improved sense of satiety. It is only now I realise it has been years since I actually felt full eating food and the GLP-1 agonist has given this back to me.

tl;dr

While traditionally considered a ‘Type 2 drug’, there can be benefits in incretin mimetics for all Types of diabetics. For all Types we have the general benefits of:

• Lowering blood pressure
• Lowering the risk of cardiovascular disease
• A sense of feeling ‘full’ which may be lacking in diabetics
• A lowering of HbA1c
• Weight loss (especially for the GLP-1 agonists)

For Type 2s, the benefits also include the lowering of blood sugar levels through the increased release of insulin after meals and supressed release of glucose from the liver.

For Type 1 LADAs there is growing evidence that incretin mimetics can help preserve beta cell function and prolong the honeymoon. Certainly the latest guidelines for managing LADA fully embrace incretin mimetics even if, formally, they are not approved for use in Type 1s.

In terms of side effects, incretin mimetics can cause stomach issues and nausea but, generally, these are mild and much less pronounced in DPP-4 inhibitors.

New innovations in incretin mimetics include:

• An improved once-weekly GLP-1 injection and
• An oral GLP-1 taken once-daily

While superior to similar products on the market in terms of their effects on HbA1c and weight loss, it comes at the cost of increased risk of side effects such as nausea, diarrhoea, and vomiting.

I posted this Tweet based on one of the presentations at EASD 2020.

It is worth going through some of the details because it seems incredible that as little as one hour a week of cycling really reduces all-cause mortality by more than 20% in diabetics. It is also a great study to see the limitations of research and statistics. As usual, if you want to cut to the chase, head on over to the tl;dr section.

Details of the Study

Presented by Mathias Ried-Larsen, data was taken from the “European Prospective Investigation into Cancer and Nutrition” (EPIC). This is a massive study across 10 European countries with over half a million participants looking at factors such as diet, environment, lifestyle, and chronic disease.

They took the data and filtered it to people with diabetes at the start of the EPIC study and for which relevant data had been recorded. This brought the number of participants down to 7,513 of which 63% were confirmed to have diabetes with the others being self-reported. A second cohort was considered at the second examination point to see how a change in cycling habits changed mortality rates. This second group comprised of 5,506 people.

The forms of mortality looked at were all-cause mortality (dying for any reason) and cardiovascular mortality (presumably because it is a common killer and one which is a higher risk in diabetics).

Looking at other factors of the diabetes group, it was seen that the participants were mostly middle-aged and overweight, and most did no cycling at all.

Despite the shrinking cohort numbers, they still obtained the graph I tweeted.

The bars on the four points can be thought of as the error in the value (with this level of error we are 95% confident the value is correct, equivalent to a p-value of 0.05 and is considered statistically significant). So, for example, if I do between 1 and 59 minutes of cycling in a week, my risk of all-cause mortality (ACM) drops to somewhere between 60% and 95% of the baseline risk.

The presenter claimed the covariates (other factors we know about the people) were statistically removed from affecting the numbers attributed to the cycling. So, for example, given women generally live longer than men, this could have an effect on the results so this was accounted for when looking at the results.

The presenter further claimed that there was a j-curve relationship with the data i.e. the benefits are reduced at the 300+ minute mark. To explore this, rather than bucket the cycling times into four groups, they looked at the cycling times as they were i.e. a continuous spread of values between zero and nine hours of cycling per week.

While there is a curve with a maximum benefit around 4-5 hours, there is a fairly wide error margin (UCL = Upper confidence level, LCL = Lower confidence level i.e. the upper and lower values with a 95% confidence of being right). In other words, while the curve seems to head up after five hours, the error means it could just as easily be heading down to between 0.6 to 0.7. Similar results were obtained when cardiovascular mortality was specifically examined.

Next was the review of the effect of changing cycling habits.

The takeaway here is starting to cycle yields at least a 10% reduction in all-cause mortality while maintaining a cycling habit reduces risk by between 20% and close to 50%. For cardiovascular risk, maintaining a cycling habit had slightly better results with the risk reducing by 30-60%.

Recognised Limitations

The presentation did talk at some of the limitations:

• Confounding factors: As mentioned they looked at the influence other factors, such as age and smoking had but claim their results still stand
• Medication: There was no information on the medications being used by the diabetics and the effect they would have on mortality
• Underlying disease leading to less exercise and more mortality (reverse causation): As with the confounding factors, they looked at the potential influence and ruled it out as affecting the results
• There was no distinction in EPIC between Type 1 and Type 2 diabetes so no conclusions between the Types could be made but it is assumed the distribution in the study is close to the general population and, therefore 80-90% of the cohort was Type 2

tl;dr

For middle-aged Western European diabetics, the study showed:

• Cycling reduces all-cause mortality and cardiovascular mortality
• The level of benefit is harder to quantify but, the best benefit was shown to be at around 4-5 hours per week of cycling where the reduction in risk was roughly between 20-40%. Additional cycling may be of benefit but the error margins were too high to confirm this one way or the other
• Starting a cycling habit or maintaining one shows benefit with the most benefit being for someone who maintain a cycling habit with the reduction in risk being between 20-50% for all-cause mortality and 30-60% for cardiovascular mortality
• There was no distinction of Type so it is best to assume these results apply most strongly to Type 2 but I can see no reason why it would be different to Type 1s except for the additional risk of hypo if insulin dependent