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Medtronic Insulin Pumps

The 780G Medtronic Insulin Pump is an Automated Insulin Delivery (AID) Device using the Medtronic sensor and algorithm (SmartGuard) indicated for those on 8 units or more of insulin per day. When engaged, it may toggle basal up, down, on or off and may add auto-corrections up to every 5 minutes. Auto-basal and auto-corrections are determined by the algorithm, not by any manually inputted programming. The algorithm adjusts dosing parameters each midnight based on TDD from the past 6 days. For a comparison between AID pumps, click here. 

780G

1. SAFETY CONSIDERATIONS

  • As per starting any AID pump, if the A1c is significantly elevated in the double digits, consider talking with the patient and physician about setting a higher glucose target to start. Rapid A1c improvements (e.g. 2% over 3 months) have been associated with changes in retinopathy and rarely, painful treatment induced neuropathy of diabetes (TIND) or insulin edema.
  • As per any AID pump, if a manual bolus is required for the prevention of DKA, advise the patient to use manual mode for a least 3-4 hours until resuming SmartGuard.
  • Advise the following as a starting point for backup manual rates for the 780G:
    • Glucose targets: 5.5-6.7 mmol/L
    • ISF (100/TDD)
    • Basal rates: TDD/2/24 (ideally < 50% of TDD)
    • Carb Ratio – same or adjust as needed depending on basal-bolus split when in smartguard

 

 

2. ADJUSTING 780G PUMP PROGRAMMING

 

A. WHAT CAN BE ADJUSTED

  • Only these features, below, can be adjusted when in SmartGuard.
    • Targets: 5.5, 6.1, 6.7 or 8.3 mmol/L (8.3 has no auto-corrections)
    • Auto-corrections can be turned 'on' or 'off' for targets 5.5, 6.1, 6.7 mmol/L. They are 'on' by default.
    • AIT (Active Insulin Time): 2 to 8 hrs. NOTE: This setting name is a misnomer. It does not change how the algorithm interprets the duration of insulin. The algorithm knows the insuiln acts for longer than 2hr.  It is more accurate to think of AIT as "Algorithm Intervention Time" or possibly "Autocorrection Intervention Time". This setting determines how agressive auto corrections will be. The lower the number, the more agressive. 
    • Carbohydrate Ratio
  • Auto- basal and auto-corrections cannot be adjusted by the user. The algorithm adjusts these elements every midnight based on the last 6 days’ total daily dose (TDD) of insulin and other factors.
  • Note: It may take a few days or weeks for the system to adapt. Many patients will run a bit above the target glucose setting. 

 

B. ADJUSTING FOR HYPOGLYCEMIA

  • Ask if taking acetaminophen in any medications including cold meds and Robaxacet (or equivalents for back discomfort). Acetaminophen is known to cause falsely elevated glucose readings in the Guardian Link sensors.
  • Assess if over-estimating carb intake.
  • If carb counting is challening for the patient, consider carb amounts for individually determined "small, medium or large" meals. 
  • If boluses are AFTER eating, explain that this is providing too much meal insulin (full meal bolus + increase auto-basal / auto-corrections as the glucose levels rise). Click here to go to the heading "Bolus Basics" and learn how to address missed or late bolusing. .
  • If persistent lows without a bolus, consider higher target
  • If persistent lows after auto-corrections, consider longer AIT
  • Weaken the Carb Ratio (increase the carb in the ratio), if exercise is not a factor
  • If lows between meals or overnight, remind those who regularly miss boluses to input even a few grams of carb. Otherwise, the system interprets all the insulin delivered as being needed for basal. Eventually, it increases basal insulin (reprograms each midnight based on last 6 days). Note: It interprets 5 hours with no carb input as “fasting”. Additionally, a higher overnight target may be set. 
  • Following periods of increased insulin requirements (steroids, illness, unusually large portions/binging or prolonged stress) suggest using the temp target of 8.3 mmol/L (which has no autocorrections) for a few days until the algorithm readjusts.
  • Assess if suggestions for exercise are needed (see below)
    If patients are  unsure of how much they will eat, consider pre-bolus for the grams they are certain they will eat. Enter additional grams of carb & boluses as they consumed later.
  • Assess patient bolusing practices.
    • Frequent lows and subsequent fears can cause patients to either miss boluses or to bolus after eating or other behaviors. These can impact  algorithm decisions and result in more lows. See explanations above or in "Bolus Basics" heading below. 
    • Often, reviewing with the patient how the algorithm is "thinking'" (making decisions) changes the patient's bolusing practices and helps address the lows. This strategy involves changing behavior first to address the lows. 
    • Sometimes, the severity of the fear of lows prevents the patient from making behavior changes, regardless of the “logic” to do so. To alleviate lows & fears, consider with the patient any of the following programming changes: disable "auto-corrections", increase glucose target and/or increase Insulin Action Time. As the lows and the fear decrease, and trust in the system increases, patients may modify their bolusing behaviors. Once this is achieved, slowly adjust back to optimal settings.This strategy involves changing settings first, on a temporary basis, to address the fear and the lows..

 

C. ADJUSTING FOR HYPERGLYCEMIA

  • Optimize settings: Work towards Active Insulin Time (AIT) of 2 hr and target of 5.5 mmol/L. Ensure bolus increment is set at 0.025. Click here to see SmartGuard setup.
  • Review carb counting and bolusing  (are they bolusing?)  & pre-bolusing practices. If report shows glucose readings rising before the bolus is indicated, discuss bolus timing. 
  • If carb counting is challening for the patient, consider carb amounts for individually determined "small, medium or large" meals. 
  • If > 10 mmol 2 hr pc consider strengthening ICR (reduce carb in the ratio)
  • If on many occasions there are high readings after meals with significant auto-basal delivery continued
    • Increase pre-bolus time (if safe to do so, suggest patient set electronic reminders if needed)
    • Strengthen the carb ratio (reduce the carb in the ratio).  
  • If on many occassions there are high readings later after meals with insignificant or no auto-basal delivery (frequent, longer and unexplained periods of no basal) “Why is the basal off so much?” and especially if you see some bolus being held back by the system (safe bolus) and potentially if you see very little autocorrection:
    • Consider weakening the carb ratio (increasing the carb in the ratio). Yes, that sounds "backwards" but it is not.  Note: It may take a few days or up to 6 days for the algorithm to provide more auto-basal. Patience may be required before making additional adjustments. Revisiting 500/TDD for a carb ratio may be required. (Adjusting CR too gradually can frustrate some patients as it takes too long for the system to adjust).
    • Rationale: The auto-basal is shutting off because the system is acting to prevent future anticipated lows. Weakening the carb ratio (increasing the carb in the ratio) promotes continued basal.
    • Although there are many exceptions, it is usually beneficial to have auto-basal running for significant periods in the post-prandial period on a regular basis.  It is easier for the system to adjust insulin every 5 minutes vs deal with one larger user-programmed bolus, where its only option to protect the user is to turn basal off. 
    • Continued auto-basal may also help prevent the later high readings (or higher-in-target readings) where the system is trying to catch up after auto-basal has been “off” for long periods, sometimes hours.
  • SmartGuard's “Safe Bolus” may reduce boluses for certain meals to prevent predicted lows, sometimes leading to post-meal highs. After verifying pre-bolusing timing, accuracy of carb ratios and counting, users may add 20-30% "phantom carbs" for problematic meals or foods. See the last page of the patient handout “Safe Bolus” (click here) for this suggestion. While this can help with high-fat meals (or even short-term steroid use), it is not recommended long-term as it can reduce algorithm effectiveness and autobasal delivery.
  • Is the person adding large/frequent cannula fills to try to circumvent the system? (see adherence report). The system will not add that extra insulin into auto-basal or auto-correction needs.This will impair how the algorithm functions.
  • In rare circumstances, discuss the option to come off of SmartGuard for 3-5 days to "reset" how the system calculates basal and correction doses. 
  • Generally speaking, the system works best when most days have a "fat" pink basal line. 

 

D. ADJUSTING FOR EXERCISE

  • Suggestions will require individualizing depending on the patient, level of fitness, and the type, duration and intensity of exercise. 
  • Before Exercise Suggestion
    • 1-2 hr prior, start a temp target of 8.3 mmol/L (there are no auto-corrections)
    • Individualize. Some may choose 6.7 mmol/L and turn auto-corrections off. 
  • At Start of Exercise Suggestions
    • Start exercise in target range
    • Consume, if needed, a small amount carb before exercise without entering it into the bolus screen. E.g. for 45 minutes of moderate to high intensity exercise 10g CHO if glucose 6.7 mmol/L or less, or,  20 g CHO if glucose < 5 mmol/L. 
    • Avoid exercise if rising glucose (basal will ramp upwards)
    • Avoid exercise if high insulin on board 
    • Avoid large carb loading pre-exercise as readings may rise, then basal may rise. Auto-corrections may occur if these have not been shut off. 
    • In practice, rather than avoid exercise for some of the "Avoid" situations above, some patients have had small amounts of carb without entering it into the bolus screen and monitored glucose closely. 
  • During Exercise Suggestions  
    • Consume, if needed, small amount of carbs. Do not enter carbs into the bolus screen. E.g. 10 g per hour if long bike trip.
    • Treat lows. Avoid over-treating.
  • After Exercise Options
    • Temp target of 8.3 mmol/L (no auto-corrections possible). Individualize duration e.g. may not use at all; may require a few hours or may require 24 hr if extreme exercise.
    • Consider 6.7 mmol/L target for a number of hours or longer
    • Consider 6.7 mmol/L target and manually turn off auto-corrections
    • May need to input less carb than eating (bolus modification) at next meal. 

 

3. SYSTEM INFORMATION - 780G

 

A. CGM SETUP

  • Suspend before low: ON
  • Low limit: 3.8 mmol/L
  • Alert before low: OFF
  • Alert on low: ON by default
  • Alert on high: OFF 
  • Start new sensor during fasting period or 2-3 hr after bolusing 

 

B. SMARTGUARD SETUP & OPTIMIZATION

  • Warm-Up Period:
    SmartGuard activiation needs CGM use for at least 3 days (specifically, 48 hours from midnight after starting). For example, start CGM on Tues, can start SmartGuard on Friday, midnight.
  • Suspend Before Low During "wait" Period
    Turn on while waiting three days in Manual Mode: Main menu > Settings > Alert Settings > Low Alert > Edit  (you will see Suspend before low on/off and choose glucose level). 
  • Target:
     Although 5.5 mmol/L is the default, please consider 6.7 mmol/L for the first week or longer before moving down to ensure hypoglycemia is not a concern.( Main Menu > SmartGuard > SmartGuard Settings)
  • Active Insulin Time (AIT):
    Consider starting at 3 hr for the first week, then working down to 2 hr if no concerns with lows. The suggested AIT is 2 hr. (Main Menu > Insulin > Insulin Delivery Settings > Bolus wizard setup)
  • Bolus Increment:
    0.025 units (Main Menu > Insulin > Insulin Delivery Settings)
  • Bolus delivery speed:
    Quick (Main Menu > Insulin > Insulin Delivery Settings)
  • PreBolus:
    Advise to prebolus up to 15 minutes

 

C. AUTO-BASAL & AUTO-CORRECTION BASICS

  •  Auto-basal & Auto-Corections are determined by the algorithm. (The manual basal rates, manual ISF and manual max doses are not referenced.) The system will recalcuate auto-basal and auto-correction senstitivy each midnight, based on the past 6 days' total daily dose of insulin and other factors. See the notes under the "Bolus Basics" below re: missed bolusing on a regular basis and lows between meals or overnight.  
  • Auto-basal converts to "Safe Basal" if there is no sensor date. After 4 hours of no sensor data, the system will resort to manual mode. 
  • The Temporary Target of 8.3 mmol/L does not provide autocorrections. This target can be preset for a predetermined period of time/hours and will resort back to the chosen SmartGuard target aftwerwards. 
  • SmartGuard targets of 5.5, 6.1 and 6.7 mmol/L must be manually changed. They cannot be preset for a predetermined period of time. e.g. Patients may choose 6.7 mmol/L for a specific context but forget to reset it back to 5.5 mmol/L later. 
  • Auto-corrections
    • can be provided up to every 5 minutes if glucose is over 6.7 mmol/L and algorithm determines additional insulin is required. (Basal modulation provides additional insulin if the target is set lower than 6.7 mmol/L).
    • are not available for temp target of 8.3 mmol/L 
    • can be turned on or off for other targets: 5.5, 6.1, 6.7 mmol/L (on by default)
    • if over 30% of TDD may indicate a change is needed to carb ratio or active insulin time (if not at 2 hr). However, this is individualized. Those who forget to bolus or prefer not to bolus will have high % auto-correction and that is fine if they don't wish to change their bolusing habits.

 

 D. BOLUS BASICS on SMARTGUARD

  • "Normal bolus" is the only bolus type available for use in SmartGuard. Other bolus types like extended, dual wave, easy bolus, pre-set bolus are only available in manual mode. 
  • Pre-bolus is suggested for up to 15 minutes before the meal
  • As usual, the carbohydrate used to treat lows is not inputted 
  • The advised bolus (units) cannot be manually adjusted up or down after inputting carbohydrates.
  • "Safe Bolus" is the term used to describe the algorithm reducing or holding the bolus. This action would occur to prevent hypoglycemia if the system determined there was too much bolus on board for it to safely address.  Expect any withheld bolus insulin to be given later as auto-crorrections or modulated basal.
  • If high readings persist even after strengthening the carb ratio, see suggestions under the heading "Adjusting for Hyperglycemia". 
  • If NO boluses are given on a regular basis, this can eventually result in lows between meals and overnight. The system interprets all the insulin delivered as being needed for basal, and eventually increases the basal insulin after a few days. (Note, periods of 5 hour with no carb input are interpretted as "fasting" by the system). This may also present without hypoglycemia, but with frequent long and unexplained periods of no basal overnight. 
  • If FULL boluses are given AFTER eating, this can result in lows. Too much insulin for the meal can be delivered. (A full late bolus + increased auto-basal + possible auto-corrections as the glucose level rises.)
  • To avoid lows with late bolusing suggest:
    • If bolusing up to 30 minutes after eating, enter half the carb (equates to half the bolus.)
    • If bolusing greater than 30 minutes after eating, do not input the carb. (Equates to NO meal bolus.) Allow auto-corrections and auto-basal to attempt to address. (If patient is insistent on bolusing, advise a dramatic reduction in the amount of carb eaten.)
  • Simplified Bolusing

 

 

4. Medtronic Training Resources & Contacts

A. FOLLOW-UP & QUICK REFERENCE GUIDES

 B. TRAINING RESOURCES

 

C. COMPANY CONTACTS