How I solved my son’s biggest diabetes mystery


Blood sugar chaos, unexplained hypos – they might be caused by insulin freezing in your home fridge. Sophie, mother of a young boy living with T1D, discovered that the temperature in her fridge often fell to below zero, causing her son’s Humalog to become less effective. How did she do it? Read her story below.

It’s dinner time. We’re setting the table, when I remember that it’s time to refill Titou’s pump reservoir. I take out the diabetes kit box… oh shoot! I forgot to also take a new vial of insulin out of the fridge beforehand. 

No big deal, this is not the first time we put cold insulin in the pump. We store about 3 months’ supply of insulin in our fridge. I usually make it a point to take the oldest vial of the stock, so I don’t leave some insulin to expire by accident. But I am in a rush now. I open the fridge and take the first vial that I reach, which happens to be the newest one.

The following days, Titou’s blood glucose is out of control!

I spend the next two nights treating his hypos… I decide to reduce the basal rate progressively day by day. Unexplained fluctuations like these occur often and are very frustrating, but I say to myself: “It is not the first time that his needs change suddenly: it’s puberty, it’s diabetes, it’s life…” and that could have been the end of it…

Sophie’s son Titou

Unexplained hypos and insulin potency

Except that a few days ago, I had met a fellow T1D, Amin, at the #DOCDay (Diabetes Community Online) in Munich. He presented a connected temperature sensor for insulin called MedAngel, which he had invented out of his own need. Amin started his project 2 years ago, after his stock of insulin had gone bad.

He explained to the audience how his blood glucose had been out of control, how he traced the cause to his refrigerator freezing the insulin and how he came up with a monitoring solution to avoid this from ever happening again.

Now with Titou’s unexplained hypos, I recognised a similar situation and I thought: what if the insulin carefully stored in my fridge was no longer 100% potent? Arrgghh!!!

A smart thermometer for insulin?

I always store insulin in the lower drawer. Now that I thought about it, I sometimes do need to remove some ice beneath the drawer. I once put a thermometer in the box and it went down to 1°C at that time, however, I did not realize that a normal fridge can get even colder. I needed to know, so I called Amin to ask if I could use one of his MedAngel sensors, and he kindly sent me one (it was not commercially available at the time).

As soon as I received the sensor, I installed the application on my phone, chose “Humalog vial” and placed the sensor next to my vials… And in no time, I got the alarm that the storage temperature of our insulin is below freezing temperature!

The sensor in Sophie’s fridge next to Humalog vials. The app receives the info via Bluetooth: Too cold. 

What I discovered:

Humalog must be stored at a temperature between 2°C and 8°C and the app showed -1°C! Now I know for sure that my vials were regularly exposed to temperatures below zero! Goodbye small vials :’( Then it hit me: for years we were using insulin which had been stored 3 to 4 months at freezing temperatures! I also realize that we were so lucky that his unexplained hypos were not more severe and that nothing serious happened.

Making sense of blood sugar chaos

It is basic knowledge that temperature affects insulin effectiveness, however, I did not think of it until then. I was always telling myself:

“There is nothing to do, diabetes is like that, it changes, sometimes we have to increase the basal by 150% without knowing why, it’s one of life’s mysteries…” when in fact I was using insulin with varying potency.

Sometimes it was less potent, and it caused hyperglycemias that were very hard to handle, rough nights, trips to the hospital…
Then, when taking a bottle of with almost 100% potency the basal rate was too high and it caused hypoglycemias, rough nights, trips to the school’s infirmary…

Here are the average blood sugar values from changing from an old bottle of insulin to a new one directly from the pharmacy. Here is no question about that insulin being more potent than the previous, I want to slap myself for not thinking of it sooner! As you can see, he suffered from a lot of hypos that were very low, it was quite dangerous… I am glad that everything is okay now.


Sophie, T1D mom&blogger on Diabetoo


blame myself: it’s been a while since I was wondering about correct insulin storage, but since I had no solution (a friend once suggested to put colored water in small bottles made of thin glass, that explode when the water freezes, as an indicator, I was ready to do it …), I could not solve this problem. Amin did, and I am really grateful that he was brave enough to build his own business and came up with an idea that is going to change my son’s life, and mine (and surely yours too!). Since we’ve been using consistently 100% effective insulin, once the basal rate was properly adjusted, his blood sugar levels are perfect and it’s a pleasure to see these graphs!


This post originally appeared on Sophie’s blog in October 2016. She received a sensor without expectation to write about it and kindly allowed us to repost it here.

To learn more about MedAngel and find our online store, visit our home page.

Oct 17, 2017
Pharmaceutical sciences, now solving problems around meds and temperature.