Hybrid Closed Loop - Smart Guard Management

Hypogylcaemia (Low blood glucose levels)

One of the main aims of Smart Guard is to improve time in range (TIR) without increasing risk of hypoglycaemia.

When using Smart Guard there is the choice of 3 targets: 5.5, 6.1 or 6.7 mmol/L, your clinic team will assist in choosing the most appropriate target for your child. It is designed to achieve the best time in range without increasing the risk of hypoglycaemia.

As the sensor glucose (SG) level changes, the basal insulin delivery is adjusted accordingly. If the sensor glucose level is trending low, the basal delivery is reduced to prevent hypos.

However, hypoglycaemia can still occur. Treat using fast acting glucose but give half of what you would normally give for hypo treatment.

For example:

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This is due to the action of the auto basal insulin delivery:

• When the sensor glucose level is dropping the auto basal will reduce or no insulin delivery to accommodate this.
• Once hypo treatment is given the blood glucose level rises and the auto basal will also increase.
• If hypoglycaemia is over treated there will be an increase in basal insulin and a possible autocorrection delivered which may cause rebound hypoglycaemia.

Re-check the Blood Glucose Level in 15-30 minutes.

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Hyperglycaemia (High blood glucose levels)

Possible causes:

1. Missed meal bolus- auto basal / auto corrections aren’t intended to manage significant highs, which can occur from missed meal boluses or highly underestimated carb intake.
2. Meal Bolus given too close to the meal
3. Correction bolus not given
4. Flow of insulin interrupted:
   1. blockage or kink in the infusion set
   2. cannula bent or dislodged
   3. set not connected properly
   4. air bubble in the infusion set
   5. pump is disconnected/ suspended for too long
5. Site not absorbing i.e. due for a line change
6. Site infection
7. Illness
8. Stress
9. Decreased activity

Problem Solving

• Bolus for all meals and double check correct carb counting
• Bolus for meals 15 minutes before eating to match insulin dose with carbs eaten
• If a meal bolus has been forgotten deliver a correction bolus as requested by the pump.
• If meal bolus has been forgotten and
  • Identified within 1 hour of eating enter 50% of carb intake and recheck in 1 hour
  • Identified more than 1 hour after eating give correction and continue to monitor hourly until target has been achieved

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Autocorrections

SmartGuard may deliver Auto Correction boluses, if required, depending on calculations for insulin needs. The Auto Correction target is set at 6.7 mmol/L. Auto Correction uses SG readings and can be delivered every 5 minutes when:

• Maximum Auto Basal delivery is reached AND
• SG is above 6.7 mmol/L.

The system uses your active insulin to determine when an auto correction bolus is needed and auto correction boluses count toward active insulin totals. When Temp Target is set, auto correction boluses are not delivered.

SmartGuard Technology

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Sick Day Management

General Points:

• Never stop insulin, as a lack of insulin leads to ketone production
• Test blood glucose levels and ketones (regardless of BGL) every 2 hours.
• Paracetamol may affect how the CGM reads sensor glucose levels
• Patient to stay in SmartGuard as much as they can by following pump prompts and giving corrections
• If unable to give enough corrections to reduce high glucose levels may need to exit into Manual Mode and use temporary basal settings from 150%
• Basal settings in Manual Mode need to be reviewed regularly to ensure they are similar to SmartGuard Basal amounts
• The SmartGuard algorithm calculates the total daily dose every 24 hours, so the basal rate may be high when returning to SmartGuard feature, may need to use exit if basal is too high and hypoglycaemia is experienced post recovery.

Ketones:

• Exit to Manual Mode if ketones are present.
• Give insulin injection for ketones
• Stay in Manual Mode for 3 hours (duration of action of insulin) before returning to SmartGuard

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Exercise Management

For Aerobic Exercise which include sports and activities such as running, swimming, dancing, football, netball, basketball, kickboxing or bike riding your child may experience hypoglycaemia.

To prevent hypos in SmartGuard, use the Temp Target which is set at 8.3mmol. This will allow the Auto Basal to adjust to a higher target.

• Set the Temp Target for 1-2 hours before exercise, depending on current glucose levels
• The temp target can continue until 1-2 hours after exercise if glucose levels are trending low
• Your child may need to use the Temp Target over night for up to 12 hours to prevent post exercise hypoglycaemia
• Consider running Temp Target all day at school if your child is too young to remember to put Temp Target on at the right time and the school is unable to assist
• Consider under bolusing the meal just before sport for younger children

If hypos occur even with use of temp target or for spontaneous exercise:

• Suspend the pump during exercise
• Consider giving a carbohydrate snack immediately before exercise if glucose level is < 8.3mmol/L
• If the carbohydrate snack is given more than 10-15 minutes before exercise without a bolus the Auto basal will increase to cover rising glucose levels and may cause a hypoglycaemia during exercise
• When using SmartGuard we need to re-think how carbs are given before sport.

For Anaerobic Exercise, which include sports and activities such as weight training, sprinting or jumping, basically any exercise that consists of short exertion and high intensity movement, may cause your child to have hyperglycaemia.

To prevent high glucose levels during this type of activity test BGL more frequently and consider giving correction doses if recommended by the system.

To prevent hypos, use the Temp Target during and after exercise

For any sport or activity consider how this has been managed previously and adjust based on the impact of Auto Basal delivery.

It is very individual and to understand how exercise impacts your child’s glucose levels in SmartGuard it may be best to observe and record strategies used and the success achieved.

REMEMBER: SUSPEND IF DISCONNECTING YOUR PUMP FOR LONGER THAN 15 MINS.

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Meal management - Food Tips

Meal Boluses:

• Should be given at least 10 - 15 minutes before eating to optimise insulin action
• However:
  • if BGL is 4.4 – 5 mmol/L bolus 5 minutes before eating
  • if BGL is 4 – 4.3 mmol/L bolus just before eating
• Hypoglycaemia may occur if your child is not bolusing for meals early enough
  • This may occur if the bolus was delivered at the time of the meal or after they have started eating (depending on glucose levels).
  • This is due to the Auto Basal insulin increasing to match the increasing sensor glucose reading from the meal.
  • When the patient gives the bolus insulin for the meal in addition to the already increased basal insulin there is too much insulin on-board, this can cause hypoglycaemia.

Missed or forgotten bolus:

If your child has forgotten to bolus for a meal, they can give 50% of the bolus.

For example, if the meal was a 40g carb meal they would bolus for 20g of carbs instead, if they remembered within 1 hour after eating, this would prevent the rebound hypo.

If it is longer than this do not enter carbohydrates just give the recommended correction bolus.

Delayed or extended glucose rise after a meal:

Meals with higher fat or protein meals (that also have carbohydrates) may show a fall in glucose, post bolus, then an extended rise 2-5 hours later.

There are two ways to manage this as there is no dual, square or extended wave in SmartGuard.

1. Enter the carbs before the meal and allow the Auto Basal to adjust as needed if there is a delayed or extended rise. This is a good option for a one-off meal.
2. Give extra insulin and split the higher dose of insulin into two boluses*. This is a good option for a regular family meal that results in delayed glucose rises.
   1. Add 20% to the carb dose. i.e. if 40g of carbs add 10g. Total 50g bolus.
   2. Give 60 – 70% up front before eating (60% of 50g is 30g)
   3. Give the remaining 30-40% 1 – 1 ½ hours after (40% of 50g is 20g)

For example, if trialing a split dose 60 / 40 percent split enter 30g of carbs into the pump and bolus and then 1-1.5 hours later you would enter another 20g and bolus for the remaining carbs in the meal.

This method may require some trial and error to see which types of food need
split dosing and with what ratio.

You may need to adjust the amount of extra insulin or the timing or percentage of your split doses. Contact your clinic dietitian on the best way to manage with these types of meals.

Bedtime snacks

It is a good idea to refrain from giving your child a snack at bedtime, without bolusing, to prevent hypoglycaemia overnight. The Auto Basal will reduce to prevent a hypo from occurring if SGLs decrease. It may take a bit of getting used to, but you will gain trust in the system.

Fake Carbs

Sometimes it may seem like a good idea to manipulate the system by bolusing for fake carbs in order to give more insulin and bring SGL’s down faster, as the correction bolus may seem too conservative. However, it is best to work with your clinical team to optimise pump settings to manage hyperglycaemia.

School Management

Update the school action and management plan to include SmartGuard.

Keep information for the school SIMPLE by providing these options:

Exercise

• The student may have a carb snack just before exercise if < 8.3 mmol/L
• The student/teacher can suspend the pump
• A temp target could be set 1-2 hours pre exercise and or post
• The student could have half the carb bolus at Morning tea or Lunch if activity is within 10-15 minutes.

Treating Hypoglycaemia (Low GL)

• Give half the normal hypo treatment when in SmartGuard Treating

Hyperglycaemia (High GL)

• The teacher/EA may need to assist or observe corrections more often and follow the prompts the pump suggests

Responding to Alarms

• If BGL >13mmol or 16mmol the pump will alarm and patient will need a correction bolus
• Follow pump prompts and alerts

School Camps

• Complete the camp management plan at https://www.diabeteswa.com.au/professionals/training/diabetes-awarenessin-schools-2/diabetes-action-and-management-plans/
• Bolus as normal (before meals)
• May need to under bolus for carb intake if activity scheduled directly after meals
• Run the Temp Target for the whole camp