Categories
Auto Mode

Final Post – 2 Years Later on Medtronic MiniMed 670G and AutoMode

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.

Categories
Auto Mode Medtronic MiniMed 670G Pump Settings

Spike Control is Auto Mode’s Biggest Weakness for the 670G

Now that I have been using Auto Mode for the Medtronic MiniMed 670G for the last one-and-a-half years, I can say that spike control is one of the major weaknesses of this closed loop system.

Auto Mode does a decent job of controlling BGs for low to moderate glycemic index foods. But for high glycemic index foods, the pump struggles because of inherent Auto Mode safeguards.

As a safeguard against hypoglycemia, the pump pauses basal and microbolus delivery following meal bolus delivery for close to thirty minutes. This makes it very hard for the pump to catch up with a meal related BG spike.

In the photo snapshot, as soon as I bolus for my breakfast comprising a cup of tea and a piece of toast, there are purple dots dissapear for close to thirty minutes (purple dots signify every time the pump dispenses a microbolus or basal dose).

As you can see, there is a period of close to thirty minutes (green box) where the pump does not dispense microbolus or basal dose. In cases of high glycemic index foods, the MiniMed 670G cannot catch up with the runaway BG numbers.

According to Medtronic, this period of no microbolus or basal delivery is needed to determine the BG trend after meal bolusing.

Even though the pump resumes microbolus and basal delivery, it is too late and the BG spike is inevitable.

Waiting longer than the 5-15 minutes before eating recommended by Medtronic somewhat helps. But it is still hard to recover from 30 minutes of no insulin delivery.

The reason manual mode is so good with spike control as compared to Auto Mode is because manual mode allows for a good balance between bolus and basal. The user can be able to adjust the basal does just right to assist the meal bolus counteract BG spikes.

Categories
Auto Mode Guardian Sensor Medtronic MiniMed 670G

A year Later – Success with Auto Mode

Exactly a year ago on this day, I met with my diabetes educator for my Medtronic MiniMed 670G training. Two weeks later I started using Auto Mode.

Along the way, I started documenting my journey on ButDoISay, nearly gave up on Auto Mode and certainly drove my endocrinologist crazy by constantly changing my delivery settings.

Her very words during our last appointment were: “Why change something if it ain’t broken”

Since we have a good rapport my answer was “You know, the scientist in me pushes me to fiddle with the settings. Right?!” And she just laughed.

Finally 100%. I took a year but I think am getting there
Time in Range is 91% in the last 7 days

Fittingly, yesterday for the first time I was 100% in Auto Mode and 100% in Target Range. Woohoo! I just can’t believe how the algorithm has learned my sugar basal rhythms in the last one year.

But seriously, the last year was also a very stressful year for me. Our youngest daughter was diagnosed with Autism at the start of 2018 and my life was completely changed. All of a sudden I started noticing all the missed milestones and my schedule was now filled with Autism parent training, speech therapy, and occupational therapy appointments.

However, the most stressful thing for me was not being ready to accept that my daughter was fine in her world and I am the one who needed to change to make sure I gave her the love and support that she needed to navigate around my world.

One thing though I did not have to worry so much about was: Do I have the correct basals set to deal with the stress and emotional roller coaster that came with our daughter’s diagnosis? This is quite liberating and freeing.

AUTO MODE TO THE RESCUE

Through this time, Auto Mode worked like a champ and I can undoubtedly say it has done a better job of adapting to all the stressful events of 2018 than I would have done if it was left to me in Manual Mode.

I no longer have to worry so much about lows when taking my daughters to two separate schools or doing yard work. (I had been diagnosed with uncontrolled severe hypoglycemia in 2013 when I got my first pump. I am also a late onset Type 1)

Despite Auto Mode’s many shortcomings that could keep you awake all night, I am glad that I never gave up.

WITH AUTO MODE PATIENCE IS KEY

This is my advice: If you are thinking of giving up on Auto Mode because of all those highs that you can’t seem to control, just give it time. For me it has taken close to a year to finally get to where I am comfortable with my numbers.

The Auto Mode algorithm seems to be more adaptive than I even thought. And the more data you feed it, the better it will become.

 

Categories
Auto Mode CGM Sensors Guardian Sensor

Recovering from the “Sensor Updating” Message

Every now and then you will get this dreaded message on your Medtronic MiniMed 670G:

Do not Calibrate. Sensor Updating. Do not Calibrate. Sensor Updating. This could take up to 3 hours

In most cases the sensor updating message comes on because I have entered consecutive meter BG readings that the sensor does not like.

You know that chances this will mean that you have to replace your all-valuable sensor when it is all said and done. I have not had so much luck with the “updating” part. Almost always the story ends with “replace sensor.”

As a matter of fact if I get this error towards the end of life of the sensor, I will just change the sensor than wait for 3 hours.

What i do when i get the “sensor updating” message

To salvage a sensor that is only a couple days old (around 4 days or less), I disconnect and then reconnect the sensor following the procedure below:

  1. Very carefully remove the tape and completely disconnect the transmitter just like you during sensor change-out.
  2. Charge the transmitter once again.
  3. Remove the transmitter from the charger.
  4. Reinsert the sensor and start a new connection and go through warmup under
    Options>Utilities>Sensor Settings>Sensor Connection>Start New Sensor.

Categories
Auto Mode Basal Settings PUMP REVIEW Pump Settings

Shortcomings of the Medtronic MiniMed 670g, Auto Mode and Guardian 3 sensors

From the onset let me say I think the Medtronic MiniMed 670G and the Auto Mode setting are a big leap forward in glucose control for Type 1 diabetes. Closed loop insulin pump technology is the technology of the future. Personally I foresee the insulin pump becoming an install-and-forget type of medical device in the near-future. While in no way perfect, the first iteration of the MiniMed 670G was a great step forward in this direction.

Categories
Auto Mode CGM Sensors Pump Settings

Morning Meter Fasting Glucose is much higher than Sensor Glucose

As you can see my morning fasting glucose numbers are running higher than I would like them. I feel well rested in the morning if my numbers are below 120. Above that I wake up feeling tired. I have also noticed that it is in the morning that I get the biggest differences in reading between the Minimed 670G pump Guardian sensor and my BG meter (during other times the readings are within 10 mg/dL of each other but in the morning closer to 20 mg/dL ). Not sure why the sensor consistently under-reports my BG readings, but it is at this time that I would love my sensor to be the most accurate! Most probably it might have to do with the fact that the Auto Mode algorithm is likely most conservative at night.

Categories
Auto Mode Pump Settings Treating Low and High Blood Glucose

Double-Check Sensor Blood Glucose Towards End of Life for the Guardian 3 Sensor

Double arrows pointing down on your pump is never a good thing especially if the number is 65. But towards the end of life the guardian CGM sensor, it is especially important to counter-check this reading against a BG meter reading.

It is quite common for the sensor to yo-yo between lows and highs especially on the last days of its life (displaying double arrows due to false positives and negatives in current readings).

In fact, this instability is normally a signal it is time to change your sensor especially if the numbers do not match BG meter readings.

Decided to counter-check sensor BG before treating low .
Categories
Article Review Auto Mode

A Short Article Review – Optimizing Hybrid Closed-Loop Therapy in Adolescents and Emerging Adults Using the MiniMed 670G System

Link to the Article abstract for this article titled Optimizing Hybrid Closed-Loop Therapy in Adolescents and Emerging Adults Using the MiniMed 670G System by Messer Et al. that was published on Diabetes Care in April 2018. Inbox me to see how we can get you a copy of this paper. Disclaimer.

Bottom line: Your Endo might need to really get aggressive in adjusting your carb-ratios for Auto Mode.


This article is probably the most detailed of any publicly available Medtronic sanctioned studies that actually discusses the MiniMed 670G pump and gives guidelines on how to optimize Auto Mode. It delves a little and provides references on how the HCL algorithm used in Auto Mode works and the inputs that can be adjusted when it comes to Auto Mode.

In their trials, the authors worked on optimizing Auto Mode inputs for 31 adolescent and young adult participants (14-26 years old) over a period of 3 months.

The study provides three settings that can be used to tune Auto Mode, namely: carb to insulin ratio, Active Insulin Time (AIT) and Bolus Speed (although this setting is not used or explained for the trial).

The main takeaways from this paper can be summarized as follows:

Categories
Auto Mode CGM Sensors

Upper Thigh Sensor Insertion Sites are More Accurate than Belly Sites

Bottom-line: For accuracy and fewer calibration errors I have found upper thigh sensor insertion sites better than belly sites. These sites take longer to stabilize (about 12-24 hours) but always give me very good accuracy and fewer calibration errors over the life of the sensor. Sensor values seem to match better with meter values for the upper thigh sites over the belly sites.


During my pump training, I was told that Medtronic now officially recognizes the outer side of the upper thigh as an FDA approved insertion site for the Guardian sensor. This was not the case for the Enlite sensor.

To shorten the time it will take the sensor to stabilize and enter Auto Mode, some people suggest inserting a new sensor and leave it in place a couple of hours prior to replacing the current sensor. I have had mixed results with this approach.

Categories
Auto Mode Pump Settings

Solution for the Medtronic 670G AutoMode BG Loop

UPDATE 09/10/19 – A new enhanced transmitter to resolve the BG loop issue is being issued to Medtronic MiniMed 670G owners. This has worked beautifully for me since receiving it about 3 months ago.

To request for the new enhanced transmitter follow this link.

Or you can contact your Medtronic Diabetes Educator or call Medtronic directly for one.


Couple weeks ago, I could not enter Auto Mode on my 670G for three days due to the dreaded “BG Required Loop.” As a solution, I eventually had to change the sensor to be able to re-enter AutoMode.

God knows I have tried to resolve the issue using every advise given online in forums (including trying to “fake” the system by entering a number just above or below your last entry) but these have only worked only a couple times.

What I think Causes the BG Required Loop

At issue I think is the way that the 670G calibrates the Guardian sensor. It seems to be programmed to validate the BG you’ve entered into the system probably based on the ISIG history and its predictive model of where your BG readings are trending towards.

Sounds complicated?

Categories
Auto Mode CGM Sensors Pump Settings

Kicked Out of Auto Mode….Again!

Guardian Sensor Stability and Auto Mode

I have been trying to get back to Auto Mode for the better part of the day today.

As you can see my readings in manual mode were not so bad and I would say those were stable sensor readings. I am not sure what reading variance the Auto Mode algorithm considers acceptable to enter Auto Mode.

Variance does not look too shabby but Auto Mode did not like it.

Categories
Auto Mode

Review – What I Love (and Hate) about the Minimed 670G Auto Mode Feature

The MiniMed 670G in AutoMode. The blue shield means it is all-systems-go and in AutoMode.
The MiniMed 670G in AutoMode. The blue shield means it is all-systems-go and in AutoMode.

There is a lot to like about the Auto Mode feature for the Medtronic MiniMed 670G. This feature is analogous to self-driving technology where a car employing this technology drives along fine until the camera hits a blind spot. The same happens for Auto Mode, it works fine until an unexpected situation arises and the Auto Mode algorithm cannot handle this sudden change.

The closed-loop hybrid system is ground-breaking technology that as a research scientist I really appreciate. Yes, it is a work in progress. But its current intricacies and potential to give people with Diabetes better control of their glucose numbers and more freedom to pursue other important things in their lives is really laudable.

Categories
Basal Settings

For Manual Mode Basal Settings are Everything

Importance of Basal Settings

After nearly giving up on my pump, I found the very popular book by Gary Scheiner, Think Like a Pancreas: A Practical Guide to Managing Diabetes with Insulin. (Amazon) – I think this is a must-have book for people who want tight control of their glucose numbers.

At this point, I had uncontrolled, severe hypoglycemia. With a new-born baby, this was not just a drag on my life but it was a bit dangerous. I do not know how many gallons of orange juice I drank to counter lows.

I had also not paid attention to the importance of fine-tuning my basals. I was using a single basal which gave me big lows at night and when I was doing practically anything that needed me to expend a little energy.

Since many new pumpers are coming from a combination of short-acting and long-acting insulin injections, the idea of basals is a little foreign as compared to bolusing.

I think educators need to spend a little more time talking about how basals are the foundation of successful pump therapy.

Categories
Auto Mode Pump Settings

Tunable Settings in Auto Mode for the MiniMed 670G

Tuning Auto Mode for the Medtronic MiniMed 670G is just like tuning an engine. Changing one setting throws off the other settings
Getting Auto Mode settings just right seems to be a balancing act – more fine tuning than just dialing settings up or down

UPDATE - I have certainly found out that dialing the Carb Ratio and Active Insulin time up and down do not necessarily mean that you will get better control. That is why it is important to work with your endo or educator to tune these settings.

——-

When it comes to Auto Mode for the MiniMed 670G, tuning the settings to get as close to your sugar targets feels a little more complicated as compared to the manual mode. This is because the closed loop system has a feedback mechanism which will likely throw-off one setting when you change another.

In the course of your day, the system is performing a balancing act between bolus and basal to keep you as close to Auto Mode’s fixed and preset BG target of 120mg/dL by introducing a third input – the micro bolus.

When it is all said and done, the user has control of two settings only, namely Carb Ratio (CR) and Active Insulin time (AIT).