Considering that Medtronic plans to release the MiniMed 780G this year, I have decided I might as well wind up my blog on my experience with the MiniMed 670G and Auto Mode.
I have compiled a set of final tips/observation for those planning to get the 670G and use Auto Mode based on my 2 year experience with the pump and Auto Mode.
Auto Mode does not adjust for diurnal trends such as dawn phenomenon.
Despite being adaptive, Auto Mode will not adjust for diurnal trends. Medtronic explicitly recommends manual correction for fasting BG numbers related to dawn phenomenon or somogyi effects.
Auto Mode does not work as well for foods high carb or high-fat foods.
Because of the conservative nature of Auto Mode, expect a spike in BG when you eat high glycemic index (GI) foods. Timing is a little tricky with this pump since there is a period of no basal insulin delivery right after bolusing.
Unless my BGs are low or dropping, I typically wait for 30 minutes after bolusing to eat high GI foods.
For high-fat foods like Pizza, you might need an additional bolus after 1 or 2 hours.
Balance between Bolus and Basal is important
Auto Mode works on input from your historical daily total daily dose (TDD). So the dispensing of bolus and basal will be a balancing act, but in relation to the TDD. So if you set your carb ratio to be so aggressive, expect the Auto Mode to cut back on the basal delivered and vice versa.
I think the jury is still out on whether the 50:50 basal bolus ratio is s needed for Auto Mode. According to my Medtronic Educator, a 55:45 bolus-to-basal ratio is the recommended starting point.
Consistency is Key.
Since Auto Mode depends on TDD history, I have found that it is important to keep my daily carb intake consistent. If you miss a meal or two the previous couple days, Auto Mode will scale down the basal to reflect the changes in your TDD.
Too much snacking will get you into trouble.
Although Auto Mode can handle small BG changes, too much snacking will get you in trouble since the system is very conservative in nature. Too much snacking also might require too much bolusing, which will force the pump to scale back on basal to meet the daily TDD limits.
Bolusing for Ghost Carbs will come back to haunt you.
Although it might seem a good idea to inject for “ghost carbs” or fake carbs to adjust for high BG, it is not. Auto Mode assumes that a meal accompanied the ghost carbs. So expect a precipitous drop in BG a couple hours later since Auto Mode does not account for ghost carbs as part of its BG correction process.
Auto Mode is only as good as the accuracy of your sensor.
Make sure that your sensor is as accurate as possible by identifying which sites give you the most accurate readings. Upper Thigh sites work best for me as compared to belly sites.
Change your infusion sites often.
Just as sensor sites, make sure that the site you are using for your infusion sites deliver insulin consistently. Rotate your sites as recommended. If your BG rises for unexplained reasons, the major culprit is normally a bad or overused infusion site.
Also remember Medtronic offers a wide variety of infusion sets. So talk to your Doctor to see whether you can test different infusion sets to see which one is best for you.
Know when to change your sensor.
Do not wait for the sensor to expire before changing your site. Remember that:
- It takes nearly an hour to charge your transmitter.
- It takes two hours for the sensor to warm up.
- It takes 30 minutes for you to reenter Auto Mode after the first calibration.
- The pump will require a mandatory calibration in 6 hours.
So if you start the sensor change-out at 7 pm, you will be up all night.
It also helps to “marinate” the new sensor about 24 hours in advance, but remember this might cut short the sensor life by a day.
Optimize your manual basal rates often for a rainy day.
There are days when you might not enter or stay in Auto Mode. So it is prudent to make sure your manual basals are good for such a time.
It also seems as if Auto Mode will “reset” if you run manual mode for a couple days. This has seemed to help where Auto Mode was delivering very little basal insulin.
Do not be too hard on yourself when on Auto Mode.
Auto Mode will test your patience on some days, but do not give up. Work with your doctor and Medtronic educator to optimize your settings. Also, be realistic on your BG targets when using Auto Mode. Auto Mode might not be for you if you are looking for tight control of your BGs.
I would say a realistic HbA1c when using Auto Mode is between 6.5 and 7.0.