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  • 1.  Libre 2 sensor warnings

    Posted 12-04-2023 12:06

    I have been using  Libre2 sensor for two years, probably overuse it, however when hypos are indicated from my iPhone12 and I don't 'feel it' I do a blood sugar. Sometimes, a slight difference, .1 - 2 mmls. And also times where there is a more substantial difference 5 - 6 mmls. I wait 15 or so minutes before using the sensor again. During the night, after injecting 18 units of long acting insulin after dinner, I get a signal, low blood sugar, half asleep I start off with 5 jelly beans, I feel it's not working, so I dive into toast/honey + a spoonful of golden syrup. My blood sugar reading has not moved. Still feeling the hypo, I wait until blood glucose reaches 5.0 + ......Does anyone else have these night time results? Daytime hypos are pretty much ok..usually fixed with jellybeans....
    thanks for any replie


  • 2.  RE: Libre 2 sensor warnings

    Posted 13-04-2023 07:37

    Hi June,
    Your night time regime is certainly worthy of a chat to your endocrinologist or even ringing up one of the diabetic educators at Diabetes Australia. Like yourself, I have always found maintaining and controlling  my night time insulin as difficult as in the morning with the well known so called dawn phenomenon.  My situation for the long acting is different in that my doses have been split between the morning and evening, however like yourself my blood sugars do drop around 2am sometimes as well after injecting my background Levimir.  There a a number of different reasons for splitting and timing of doses that needs to discussed with the endocrinologist and my situation may not be relevant for you.
    Most diabetics assume that basal is fairly stable however in the article below shows it does have a time line of peaks leading to dropping  insulin levels in the he night. I have attached a time chart for the action of basal insulin.  If this is the case it, the reason for the hypo's at nighttime could be attributed the background insulin. Otherwise the lows may be due to the timing of your fast acting insulin with the evening meal later at night.
    I have experimented with giving my bolus, Apidra much earlier than the background insulin Levimir to determine the reasons for the lows. 
    I hope that my situation can be helpful for you.

    "Know Your Insulins and their Timing"

    A good way to improve glucose levels is to track the peaks and drops in your glucose and relate how the peak and action times of your insulins correspond to low or high patterns in your glucose. Identify your glucose patterns (they ARE there!), and work to understand when each of your insulins is active. This allows you to adjust your insulin doses or food choices to stop unwanted ups and downs in your readings.

    The table below shows the start, peak, and end times for various insulins.

    When Does My Insulin Peak and How Long Does It Last?
    Action Times for Insulins
    Insulin Starts Peaks Ends Low most likely at: Usage
    Hum/Nov/Apidra 10–20 m 1.5–2.5 h 4.5–6 h 2–5 h covers meals and lowers high BGs
    Regular 30–45 m 2–3.5 h 5–7 h 3–7 h covers meals and lowers high BGs
    NPH 1–3 h 4–9 h 14–20 h 4–12 h intermediate peaking and action time
    Lantus 1–2 h 6 hr 18–26 h 6–10 h minimal peaking and longer-acting background insulin action
    Levemir 1–3 h 8–10 18–26 h 8–14 h minimal peaking and longer-acting background insulin action
    Toujeo 2 h none 36 h varies very flat, long-acting background insulin action
    Tresiba 2 h none 42 h varies very flat, long-acting background insulin action


    Rapid Insulins

    Humalog (lispro), Novolog (aspart), and Apidra (glulisine) insulins cover meals and affect the glucose afterward. Their glucose-lowering activity starts to work about 20 minutes after they are taken, with a gradual rise in activity over the next 1.75 to 2.25 hours, then falling over the next 3 hours. These insulins lower the glucose for 5 hours or a bit longer. Although their "insulin action times" are often quoted as 3-5 hours, the actual duration of insulin action is 5 hours or more. See our article Duration of Insulin Action for more information on this important topic.

    These so-called "rapid" insulins are slower than the digestion of most meals where the glucose peaks within an hour and digestion is complete within 2-3 hours. The best-kept secret on stopping post-meal spiking is to take the injection or bolus earlier before the meal and to eat more low glycemic carbs that digest more slowly.

    Regular Insulin

    The much older Regular insulin has a slightly slower action with a slightly higher risk for nighttime hypoglycemia. It works well for people who take Symlin or who have gastroparesis (delayed digestion). It is also much less expensive at places like Walmart.

    Long-Acting Insulins

    Though often thought of as being 24-hour insulins, Lantus (glargine) and Levemir (detemir) are actually 18 to 26-hour insulins. About a third of users do not get a full 24 hours of action from these insulins. Those who experience shorter activity times may also notice more peaking in activity and tend to experience lower glucose readings about 6 hours after the injection. A larger peak in activity at 6 to 8 hours is associated with a shorter action time, and vice versa. Anyone who does not take their long-acting insulin at about the same time each day can also experience gaps and stacking of insulin with a single injection a day. Smaller doses of these insulins are also often associated with less than 24 hours of activity.

    If Lantus or Levemir "wears out" before the day is done, unexplained highs often occur before or soon after the next dose is given. If one injection is given in the morning, high readings may occur before breakfast due to the lessening activity from the previous dose.

    Splitting doses of "24-hour" insulins into two equal doses with half taken in the morning and the other half taken in the evening even out dosing gaps and minimize peaking. After splitting a single dose of Lantus or Levemir, many people find they have better readings.

    Both Toujeo (U-300 glargine) and Tresiba (degludec) are the longest-acting insulins (36 hrs or more) and have little or no peak in activity. They provide a very flat and very consistent action from day to day.


  • 3.  RE: Libre 2 sensor warnings

    Posted 13-04-2023 07:43

    Occasionally I get a reading from my Libre 2 that doesn't seem right - says 6.0 when I feel low, or says I'm 2.8 when a finger prick shows 4.6.  It is not often but when it happens it is typically later in the lifetime of the sensor, around day 12 or so. I also can get compression spikes when I lie on my side in bed (L2 on upper arm).  I try and position the L2 so this doesn't happen but some times it does. It doesn't heppen very often - maybe once every few months. Also a poor aplication of the sensor, or the sensor losing adhesion can cause unpredictable readings. I use Skin Glu or SkinTac to improve adhesion, and I use a patch to protect from knocking.
    I use MDI and have adjusted my long acting insulin dosage for a flat overight, well as flat as possible) BGL. At night when there's no food or fast acting insulin affecting BGL it is purely the long acting insulin affecting BGL. If it drops overnight, take less. If it creeps up, take more. I'm talking 1 unit at a time adjustments. I also split my long acting insulin into morning and night doses.
    I don't believe LibreLink has the capability to use calibration readings. The developer of JuggLuco has an email from Abbott on what they consider adequate accuracy of  Libre 2 here. (you have to scroll down a bit). His opinion is it is not useful to calibrate the sensor. Dexcom G5/G6 can be calibrated - Dexcom Calibration. I don't know about Medtronic. Third party apps like Spike, xDrip+ Diabox have the ability to calibrate, and have rules in place that a calibration can only be enetered when BGL is stable, etc.
    I used to calibrate with xDrip+ but whilst it gave me more confidence in the readings, they weren't vastly different to finger pricks.
    That said the time delay between a finger prick (blood) and CGM reading (interstitial fluid) is in my experience variable. I've read 5 minutes and I've read 25 minutes. So any calibration technique would have to cater for such variations which would be very difficult to achieve. Maybe Mr JuggLuco is right...

    Kind regards...