I’ve been using the Medtronic MiniMed 670G pump for about 6 weeks now, in Auto Mode for about 4 weeks. I’m in Canada, so the BG units are in mmol/L instead of mg/dL (multiply by 18 to convert). I’ll convert here to mg/dL.
I’ve been having problems with the pump giving enough insulin for a correction bolus.
I discovered recently that the Inulin Sensitivity Factor (ISF) entered in the Settings is only used in Manual Mode.
I have heard at least 2 things about Auto Mode ISF: 1) The pump uses the “1800 Rule” using your average TDD over the past 6 days and 2) The pump uses machine learning
In an effort to test the first hypothesis, this morning my fasting BG was 165.6mg/dL (actually, 9.2mmol/L).
The pump offered to give me a 0.4U correction bolus, presumably to bring me down to 150, a 15.6mg/dL adjustment. This implies “the algorithm” thinks my ISF is 15.6/0.4=39mg/U.
This is a huge difference from my MM ISF of 18mg/U (actually, 1.0mmol/U).
My 6-day average TDD is 56.3542U. The 1800 rule would compute an ISF of 1800/56.35=32mg/U.
So… What’s going on here? Can anyone shed some insight? I’m very frustrated and it’s hard to resist the urge to enter phantom carbs.
Could this be another software bug due to the unit change? I’ve also recently found out that due to a software calculation error, “Rise Alert” is broken and should not be used outside the US (screenshot attached). Could this be a similar problem?