Changing Basal Insulin – I suppose it’s Biotechnology….

For a slightly different take on technology, let’s go and look at biotechnology and its relation to me. I’m diabetic and recently took the decision to change my slow acting basal insulin due to issues I had been experiencing with Lantus. Here’s where the technology bit kicks in.

The engineering (see what I did there) of Lantus (Insulin Glargine) has developed it in such a way that it is a slightly acidic formulation. When it is injected into subcutaneous fat, it precipitates into a reservoir of crystals that sit in the fat and breakdown slowly, providing a slow release, long acting insulin. While this is very clever, it comes with an interesting side effect, which I’ll discuss shortly. 

As a bit of background, I’ve lost roughly 10% body weight since the summer of 2014 and reduced my body fat percentage by around half. Obviously this leads to less subcutaneous fat. This is where the side effect comes in.

Injecting Lantus into my usual sites (thighs), I had a couple of occasions where the insulin went through the fat and straight into the muscle. When deprived of the fat in which to form the reservoir, Lantus turns into a very different beast. It effectively becomes a fast acting insulin (and I’d say it’s period of action is similar to Novo’s Actrapid in terms of “fastness”). 

Normally a fast acting insulin is taken before food, with a ratio of roughly 1 unit of insulin (a unit is 1/100th of a ml) to 10g of carbohydrate content. So for an average meal containing 70g of carbs, you’d take 7u.

I took the basal twice a day to provide a flat and consistent release profile over 24 hours. This is an injection of 10u every 12 hours and the release mechanism works by providing roughly 0.8u per hour.

Now, imagine for a moment if you will, the impact of this not being released slowly at 0.8u per hour… 

Effectively you are taking 10u of insulin with no carbs. With fast acting insulin, 1u reduces my blood sugar on average by 3mmol/l. 10 is effectively a blood sugar reduction of 25-30 mmol/l, which by any measure is a significant cliff.

Having Lantus not form a precipitate is therefore, well, very dangerous! I experienced a huge drop in blood sugar and a massive hypo as a result. Whilst I felt it, tested for it and took appropriate action, it still knocked my physically (if not mentally, thanks to a low carb diet) incapable for 5-10 mins. I suspect (but have no proof) that my blood glucose level dropped below 1mmol/l. This is dangerously low. 

The second time it happened, I had the Freestyle Libre on board and was able to see what was happening. it meant I treated it earlier, but still, the same issue had happened again. I decided that a pro-active approach was needed and discussed this issue on the diabetes.co.uk forum. This is how I discovered the operational mechanism of Lantus and the difference between it and other basal insulins.

What is this difference? The Novo insulins (Determir and Degludec) are neutral and instead of precipitating on injection, pool. The insulin is modified to be linked to Albumin protein, which means that it sticks to itself and is broken down slowly, whether in subcutaneous fat, blood or muscle. This seems a much safer mechanism of operation to me. 

On finding these differences in operation, I contacted my GP to change to an Albumin linked insulin. As this was out of his realm of expertise, he referred me to Guys and St Thomas’s for a Diabetic Clinic appointment. The result was that the consultant felt that Determir was a better fit, and this is what i was prescribed. 

As I’m making this change from Lantus (Glargine) to Levemir (Determir), I thought it may be helpful to others to keep a record of what I’m doing, steps taken and a variety of things that have gone on so that if others do it, they’ve got some idea of what to expect. I’m not going to suggest that this is the 100% correct way to do this, but it will be my experience. 

This isn’t the first time I’ve changed basal insulin. I moved from Insulatard to Lantus some 10 odd years ago, however this is the first time I’ve moved to one with greater hypo indication, so it carries a small and verifiable risk, but not what I’d call particularly worrisome. 

So let’s get started. First things first. Getting set up. 

Having agreed to move to levemir, I was told that to start with, use the same doses as I used for my split lantus. This is 10u at 9am and 10u at 9pm. Many people who move in the same direction as I am find that Levemir requires larger doses, so we will see what happens. 

Having taken Lantus at 10u the night before, I took the decision to not do the second split on the am following so that it would be flushed out before starting on the Levemir. I also have the libre so that I can keep tabs on what’s going on with my bg level, which helps a lot. 

With these decisions made, I took my Levemir dose at 9pm yesterday, into my bum (first time in 26 years), and decided that as my blood sugar was in the 6 range, I still had a couple of hours of novorapid on board and I wasn’t sure what my reaction would be, I would take my bg level up to ~8 for safety reasons. 

Then off to bed I went. Now I know I should probably have set an alarm to get me up in the night and test, but I figured that a hypo would be as effective at that, and with the dose I had taken, this felt unnecessary. 

On waking this morning, a quick scan with the Libre revealed the following:




It would appear that the combination of 10u of Levemir and my bum has induced a noticeable decline in bg overnight. The drop is roughly 4mmol/l. I’m very pleased I had that extra carb the night before. Now clearly one day is not a pattern, however, given the intensity (if not depth) of the hypo that resulted this morning, I’ll be reducing my evening Levemir dose by two units immediately.

Once we’ve got that one stabilised, it’s on to the daytime checks, with the associated fasting, which I am much less looking forward to! 

The observation I would make is that the Libre continuous data is invaluable in this process and makes the whole thing massively easier (and means that I get to sleep properly as well!).