Thursday, 14 May 2015

My FreeStyle Libre experience. Day 1-3.

I waited about 16 hours after inserting the sensor before activating it. According to other users waiting 12-24 hours have an effect on the accuracy of the sensor. I had no issues with sensor accuracy yet, right  from the start it was remarkably accurate. The sensor is very comfortable, no pain at all. I'm almost completely unaware of it.

Thus far, I'm very impressed with the FreeStyle Libre, it will be difficult to go back using only a BG meter. If Abbott does not release the Libre in SA by the end of my sensors, I'll most likely switch to the Dexcom system. You can't really manage T1D without a CGM. The amount of extra information available is just awesome! Just the advantage of checking your levels any-time is great and I almost felt guilty of checking the levels so often, it feels like you are consuming/using valuable resources (test strips?) each time, but actually the information you get is for "free".

Before I begin with my analysis, I'll just give a quick summary of how I treat my T1D. My pancreas does not generate insulin at all, so I have to inject myself with insulin in order to manage my blood glucose (BG) levels. I don't use an insulin pump, I use multiple insulin injections. My BG goes up when I eat and goes down when I inject insulin. Exercise will lower my BG, but it is not enough to control my BG, I need insulin. My body slowly release stuff throughout the day and night that increases my BG slowly, Lantus (Long acting insulin) are used to cover this BG rise. Apidra (Rapid acting insulin) are used to cover my BG when I eat. The black line in the graph shows the insulin release curve of my rapid acting insulin. The red line shows the release curve of the long acting insulin. So, it becomes a complex system to control and balance. The amount of insulin injected must match the amount and type of food eaten, exercise done and body state (sickness and other factors also influence BG levels). I don't do carb counting, it just seems too complex to exactly determine what is in the food you eat, I adjust my insulin amounts by learning from experience.

What have I learned from Day 1 ?

Below you can see the graphs generated by the FreeStyle Libre software, you can export everything to a .csv file which is very handy. The values with asterisks are BG levels tested with blood (test strips), this clearly shows that the Libre is accurate. The other values (shown with small circles on the graph) were collected when I scanned my BG with the Libre.

The spike at 10:00 is because I ate two rusks with my coffee.. I usually have to do this, otherwise I'll hypo soon after 10:00. Without the spike, the downhill from 10:00 - 12:00 will let me crash with a hypo. The question now is, what caused the downhill from 10-12 ?? It can't be the rapid acting insulin that I injected at 7am, because most of that will already be depleted (remember the release curve graph). It must be the long acting insulin, I'm injecting too much of it! Through-out the day my BG is dropping and I have to prevent hypo's by eating snacks at regular intervals. Have a look at Day 2 below, very similar pattern, eating myself out of hypo's all the time.
Lesson learned on Day 1: I need to reduce the amount of long-acting insulin.

What have I learned from Day 2 ?

Wow, look at that hypo during the night. I woke up at 3am and tested my BG. It was low. I've been low for about 3 hours! Without the Libre, I wouldn't have known that. The spike with my two rusks can again be seen at 10-12. This time a little bit lower because I did not add one teaspoon of sugar to my coffee. Remarkable what only one teaspoon of sugar can do! Same pattern of lowering through-out the day can be seen.
Lessons learned on Day 2: a) I'm having long hypo's during the night. b) One teaspoon of sugar is bad for your BG levels.

What have I learned from Day 3 ?

I reduced my long acting insulin by about 17% (4 units). I had another very long hypo during the night and did not sleep very well, resulting in struggling to maintain a good BG level around 9-11. Overall the reduced long acting insulin seems to work better, we will see how tonight goes.
Lessons learned on Day 3: a) I need to stop those night-time lows. b) When you don't sleep well, your BG levels will go up during the day. c) You can trust the accuracy of the Libre.

A summary of your low-glucose events (hypo's) are given in the report. Average duration of 100 minutes during the night !!! Life-saving information gained within 3 days of use, I don't need to say more.

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