Loop DIY AID

1. Loop users self-install an open-source app (not Health Canada approved) from the Loop Docs website (click here) onto an iPhone. They create wireless connections between the app and Omnipod pods (Eros or DASH) or older Medtronic pumps. All programming is done from the iphone Loop app. Users requiring help explore LoopDocs and various Facebook groups. 
2. Glucose targets can be individually chosen and set. 
3. Loop requires “absorption time” for all inputted carb foods. Default is 3 hrs.
4. Users can edit the amounts and absorption times of past carbs eaten, as well as the times past meals were eaten, and times future food will be eaten (to a limit). (click here). 
5. Loop has experimental parts of algorithm to enable in settings. (click here)
6. Terminology Alert: “Non-pump insulin” is the term for insulin delivered via syringe or pen. A “Manual Bolus” describes using double triangles icon to ask for a correction or input a bolus without inputting carb. A "manual bolus" is not a bolus with syringe or pen. 

1. Click entry icon (plate with utensils)
2. Fill in CARB ENTRY SCREEN: Enter grams of carb, time of meal, food type (optional presets for absoprtion), absorption time.  Then “continue” (click for image)
3. Accept or edit dose on MEAL BOLUS SCREEN. If accept, use “save and bolus” button (click for image).  If edit to 0 (zero) units, the “save without bolusing” screen is available to click. Loop will assume any saved carb will be absorbed and will need insulin. 
4. Variations of the above are discussed under hypo and hyper headings.

Everything except duration of insulin action can be adjusted in Loop. This includes and is not limited to: 

1. Basal rates (although only one basal profile with varying rates for 24 hours can be programmed)
2. Carb Ratios
3. ISF (correction factor)
4. At input of meal: grams of carb, time of meal (past or future), absorption time of carb
5. Past meals eaten or missed: grams of carb, time of meal & absorption time can be revised after the fact. 
6. "Overrides" which are presets that increase or decrease ALL insulin (basal, CR, ISF) by % and  glucose targets for time increments of 15 minutes to unlmited. 
7. Use of experimental "parts" of algorithm - set from inside the app
8. Correction range & glucose safety limited (previously suspend threshold)
9. Max bolus & max basal
10. Dosing strategy: temp basal only or automated boluses (microboluses) with scheduled basal
11. Other features unique to Loop App, including experimental parts of the algorithm

1. Loop is not a learning algorithm; insulin delivery is based on modulation of programmed rates.
2. Loop predicts glucose out to 6 hours, but the nearest 3 hours have more influence on the recommendation.
3. Glucose targets are individualized by the user. 
4. Experimental mini algorithms are available for use in the settings.
5. Basal rates and carb ratios can change significantly coming from other brands of pumps. “Testing” basal rates, CR and ISF is recommended. “Testing” basal rates, carb ratios and ISF can be important for many. An inaccurate setting (such as ISF) can compensate for another inaccurate setting (such as carb ratio) making control more difficult.
6. Loop requires “absorption time” of carbs. This plus grams of carb, time of meal can be edited after the meal has been eaten. The algorithm changes its dosing going forward. By adjusting these after the fact, the user can influence how Loop manages their insulin delivery, ultimately preventing highs and lows.
7. Loop interprets “absorption time” as 150% of the absorption time chosen, as a safety buffer.
8. Loop interprets all “saved” carbs as needing insulin at some point. Carbs can be “saved” with no insulin delivered if suggested by the algorithm or if the user decides to "zero" the insulin dose suggested and save without bolusing. 
9. Loop tracks “Carbohydrate on Board”. It calculates how many carbs have been absorbed (regardless of how many were entered) based on the glucose pattern and settings. It calculates the remaining carb that is left to absorb, assuming CHO count and absorption time is accurate.
10. Favorite foods and their carb content, absorption rate can be saved in the app.
11. Assessing TDD for basal/bolus splits may be valuable.
12. Active insulin includes all insulin delivered: bolus, basal, correction from the past 6 hours.
13. Loop app only saves 24 hours of glucose data for viewing. Many will link their app to Tidepool (click here) or Nightscout (click here) for creation of reports. 

As per most on pump, check if changes are needed to carb ratio(s). Also determine if the user is making safe edits to the "Meal bolus screen."

1. "Saved" carb entry (or absorption time) cases: 
   • Forgot to edit carb downwards after the fact, if chose not to eat everything or if overestimated carb count.  (click here)
   • Forgot that saved carbs, even without bolusing, can result in increased automated insulin delivery over time. Loop assumes that carbs saved will be absorbed. Loop does it's best to adjust, but ideally, any significant saved carbohydrate should be removed from carb entries if not eaten. 
   • Accidental double entry of carbs (e.g. saved without bolusing first, then later repeated carb entry and saved with or without bolusing).
   • Didn't go back to reduce a carb entry that had a long absorption time, e.g. didn't notice they still had significant carb on board while glucose level was in target and dropping. May have had high temp basal delivery earlier in the meal, and simply don't need the remaining insulin that a longer absorption time would give. 
   • Entering too fast an absorption time for mixed meals (some fast carb, some very slow carb e.g. sweet sauces, fatty fried dishes such as Chinese Food). It's best to enter the meal in sections eg. 20 g as fast, then save but don't deliver, then enter e.g. 60 g as slow, etc.  Review it all. Adjust. Then deliver. See Loop and Learn video here for challenging meals. 
2.  "Time" related cases:
   • Missed entering carb for a meal and inputted it after the fact using the default time of "now".  It's best to input a time in the past, closer to when the meal was actually eaten to prevent overdelivery of insulin. 
   • Bolusing too early: If the meal is more than 15 minutes in the future, it's best to modify the time in the Meal Entry Screen to when the planned future meal will occur.
   • Using the default time of "now" for slow foods, and not adjusting the absorption. e.g. pizza. Some slower foods may need "time" to start later and with a longer absorption time. (Using too fast an absorption time can lead to lows or to insulin suspensiions with later highs.) 
3. "Non-pump insulin" cases:
   
   • Gave “non-pump insulin” e.g. with pen or syringe, without inputting data into pump.
   • Entered “non-pump insulin” (e.g with pen or syringe) AFTER entering CHO (it should be entered before).
4. Bolus Failure Notification:
   • Assumed bolus failed without verifying, and gave it again. Click here. 
5. Assess if any globally impacting features are relevent. Click to heading below. 
   • User may have ignored an "override active" warning (click here) when using bolus calculator. 
6. ..

1. ISF may be too strong if:
   • lows after meals, but carb ratio is week
   • or especially if roller coaster glucose values. (click here) 
2. Integral Retrospective Correction (IRC) may be on;
   • Consider turning IRC off. This is an experimental part of the algorithm impacting corrections. It is found under settings. With it on, Loop will likely increase insulin for corrections beyond default settings, in response to recent past highs that are not responding as expected. This is problematic for safety if highs were secondary bad sets/sites that were recently changed or other situations. Click here for more information. 
3. Glucose Based Partial Application (GBPA) is off.  
   • Consider turning it on. It is an experimental part of the algorithm found under settings. It does not deliver more correction insulin overall, but changes the timing of the delivery. For example, if glucose is closer to target, less than the default 40% of correction is given every 5 minutes; if glucose is farther from target, more than 40% of correction is give every 5 minutes. Overall correction dose for the 30 minutes over which it is given is still the same as default. Click here for more information. 
4. Either one or both experimental algorithms are on and the patienty doesn't understand how they work. Consider turning off all experimental algorithms that impact corrections. They are under settings and include both e.g. IRC and GBPA listed above. 

• Programmed basal rates may be too high for certain times of the day or specific days of the week; Loop may struggle to prevent all lows even with automatic reductions in insulin delivery. While Loop only allows for one 24-hour basal profile of varied basal rates, "Overrides" can be created to accommodate different insulin needs for weekends, exercise, menstruation, or other predictable pattern variations. Click here for more on "overrides". Some Loopers may benefit from “testing” their basal rates to determine if they hold glucose levels stable with no food (click here). 
• An override above 100% may be in use. Override duration can be set in 15 minute increments up to “indefinite”. Reminder: Overrides impact ALL insulin delivered (basal, ISF, CR).
• Dosing strategy of “Automatic bolus” may be too aggressive for someone new to pump, new to Loop or for others worried about lows. The Dosing Strategy of “temp basal only” may be tried instead. Note: “Dosing Strategy” will use the term “bolus” but is referring to giving insulin to address basal (with correction) needs. One method is more gradual (temp basal) and the other is slightly more aggressive (automatic bolus). Click here for more on Dosing Strategy. 
• Physical activity may have occurred with no insulin reduction in advance (e.g. no “override”)

As per anyone on most AID pumps, assess for glucose patterns after meals, carb counting skills, carb ratios, pre-bolusing or if concerns with infusion sites, rotation, tunneling, integrity of insulin etc. 

1. Carb Ratio too weak:.
   • A more aggressive ratio may be needed. For those who are very insulin resistant, there are Loop guardrails in place that may impact the ideal choice for CR, when using U100 insulin. Click here for more information. U200 insulin may be considered in some cases. 
2. No prebolusing (perhaps fearful of lows) 
   • Try the Pre-Meal Tool (click here). It does not replace a pre-bolus but provides a lower user-defined target until carb is entered or user cancels (up to an hour max). This temporary lower range must be programmed in settings.
   • Can try “save without bolusing” if worried about going low when entering into the Meal Bolus Screen. Need to reduce suggested bolus to zero to view "save without bolusing" button. 
3. Accidently cancelling boluses 
   • It’s very easy to do. The 'bolus progress message' appears in portrait orientation in red at the top of phone; tapping it cancels the bolus. Ideally, the phone should be locked before putting it away to prevent accidental cancellations. Click here.
4. Forgot or regularly forgets to input carb
   • Ideally, enable Missed Meal Notification in settings (click here).
5. "Saved" carb entry (or absorption time) cases: 
   
   • Forgot to revise carb upwards after the fact, e,g. if chose to eat more or if underestimated carb count.  (click here)
   • Absoprtion time too short: Early insulin delivery suspensions in a meal (or meal type) that lead to higher glucose readings later, may require longer carb absorption times and possibly revised carb intake for that past meal. Patient may notice sugars are rising with no carb on board e.g after pizza. 
   • Too slow an absorption time for mixed meals with some fast and some very slow carb, like sweet sauces and deep fried foods. This can cause highs or lows. It's best to enter the meal in sections eg. 20 g as fast, then enter again e.g. 60 g as slow, etc.  Review it all, adjust, deliver.  Revisions for the portion that is "fast" or "slow" can be revised even hours after the meal.  See Loop and Learn video here for challenging meals. 
6. Bolus Failure Notification:
   • Missed notification or did not verify "bolus failed notification". This can happen when delivering meal bolus at the same time as auto-insulin delivery occurs. Click here. 
7. Assess if any globally impacting features are relevent. Click to heading below. 
   • User may have ignored an "override active" warning (click here) when using the meal bolus screen. e.g an override of more than 100% and/or a higher target. 
8. ..

• The ISF may be too strong: Interestingly, an ISF that is too strong can result in roller coaster glucose readings including high glucose readings (where auto insulin adjustments are high) and lower glucose readings (where zero basal is delivered).  The solution to some cases of recurrent hyperglycemia with yo-yo glucose readings, may be to weaken the ISF (Read more and see images in reports here.)
• The programmed ISF may be too weak. A more aggressive ISF might be needed.  Note: For those who are very insulin resistant, there are guardrails in place that may impact the ideal choice for ISF, when using U100 insulin. Click here for more information. U200 insulin may need to be considered.
• Either one or both experimental algorithms are turned off. This may be the best choice. However, if these are clearly understood by the user, they may consider using GBPA first, as safest (click here for GBPA) and adding or substituing IRC second (click here for IRC)  as the latter can deliver more correction than default, increasing risk of lows. 

1. Programmed basal rates may be too low for certain times of the day or specific days of the week; Loop may struggle to prevent highs with automatic insulin delivery. While Loop only allows for one 24-hour basal profile of varied basal rates, "Overrides" can be created to accommodate different insulin needs for weekends, menstruation, “lazy days” or other predictable pattern variations. (Click here for "overrides".) Some Loopers may benefit from “testing” their basal rates to determine if they hold glucose levels stable with no food. (Click here for "testing" programmed basal rates..) 
2. An override below 100% may be in use. Override duration can be set in 15 minute increments up to “indefinite”. Reminder: Overrides impact ALL insulin delivered (basal, ISF, CR) and can allow a target glucose change at the same time. 
3. Dosing strategy of "Temp Basal only" may set.  The slightly more aggressive Dosing Strategy of “Automatic bolus”may be tried instead. Note: “Dosing Strategy” will use the term “bolus” but is referring to giving insulin to address basal (with correction) needs. One method is more gradual (temp basal) and the other is slightly more aggressive (automatic bolus). Click here.
4. Insulin on Board (IOB) may be over 2X max bolus (click here to read).  This could be the case with occasions with considerable food. In this case, the algorithm will not deliver any auto-insulin until IOB is < 2 x max bolus. However, the Meal Bolus Screen (plate with utensils icon)  or double triangle bolus icon can still be used to deliver corrections as long as each bolus is not greater than the maximum bolus. 
5. Good to know:
   • People may ask, “Why is Loop stopping my basal when it predicts I’m going to be high in 6 hours?” Answer: The Glucose Safety Limit. If Loop predicts the glucose will be below this limit (user defined between 3.7 and 6.1 mmol/L) within the next 3 hours, Loop will suspend delivery for that 5 minute cycle, regardless of the 6 hour glucose prediction. It will reassess at the next 5 minute cycle.