OpenAPS features

Super Micro Bolus (SMB)

SMB, the shortform of ‘super micro bolus’, is the latest OpenAPS feature (from 2018) within the Oref1 algorithm. In contrast to AMA, SMB does not use temporary basal rates to control glucose levels, but mainly small super microboluses. In situations where AMA would add 1.0 IU insulin using a temporary basal rate, SMB delivers several super microboluses in small steps at 5 minute intervals, e.g. 0.4 IU, 0.3 IU, 0.2 IU and 0.1 IU. At the same time (for safety reasons) the actual basal rate is set to 0 IU/h for a certain period to prevent overdose (‘zero-temping’). This allows the system adjust the blood glucose faster than with the temporary basal rate increase in AMA.

Thanks to SMB, it can basically be sufficient for low-carb meals to inform the system of the planned amount of carbohydrate and leave the rest to AAPS. However, this may lead to higher postprandial peaks because pre-bolusing isn’t possible. Or you give, if necessary with pre-bolusing, a start bolus, which only partly covers the carbohydrates (e.g. 2/3 of the estimated amount) and let SMB fill up the rest.

The SMB feature contains some safety mechanisms:

  1. The largest single SMB dose can only be the smallest value off:
    • value corresponding to the current basal rate (as adjusted by autotune/autosens) for the duration set in “Max minutes of basal to limit SMB to”, e.g. basal quantity for the next 30 minutes, or
    • half the amount of insulin currently required, or
    • the remaining portion of your maxIOB value in the settings.
  2. Probably you will often notice low temporary basal rates (called ‘low temps’) or temporary basal rates at 0 U/h (called ‘zero-temps’). This is by design for security reasons and has no negative effects if the profile is set correctly. The IOB curve is more meaningful than the course of the temporary basal rates.
  3. Additional calculations to predict the course of glucose, e.g. by UAM (un-announced meals). Even without manual carbohydrate input from the user, UAM can automatically detect a significant increase in glucose levels due to meals, adrenaline or other influences and try to adjust this with SMB. To be on the safe side this also works the other way round and can stop the SMB earlier if an unexpectedly rapid drop in glucose occurs. That’s why UAM should always be active at SMB.

You must have completed objective 8 to use SMB.

See also: OpenAPS documentation for oref1 SMB

Max U/h a temp basal can be set to (OpenAPS “max-basal”)

This safety setting determines the maximum temporary basal rate the insulin pump may deliver. The value should be the same in the pump and in AAPS and should be at least 3 times the highest single basal rate set.

Example: 
Your basal profile’s highest basal rate during the day is 1.00 U/h. Then a max-basal value of at least 3 U/h is recommended.

But you cannot choose any value. AAPS limits the value as a ‘hard limit’ according to the patients age you have selected under settings. The lowest permitted value is for children and the highest for insulin-resistant adults.

AndroidAPS limits the value as follows:

  • Child: 2
  • Teenage: 5
  • Adult: 10
  • Insulin-resistant adult: 12

Maximum total IOB OpenAPS can’t go over (OpenAPS “max-iob”)

This value determines which maxIOB has to be considered by AAPS running in closed loop mode. If the current IOB (e.g. after a meal bolus) is above the defined value, the loop stops dosing insulin until the IOB limit is below the given value.

Using the OpenAPS SMB, max-IOB is calculated differently than in OpenAPS AMA. In AMA, maxIOB was just a safety-parameter for basal IOB, while in SMB-mode, it also includes bolus IOB. A good start is

maxIOB = average mealbolus + 3x max daily basal

Be careful and patient and only change the settings step by step. It is different for anyone and also depends on the average total daily dose (TDD). For safety reason, there is a limit, which depends on the patient age . The ‘hard limit’ for maxIOB is higher than in AMA.

  • Child: 3
  • Teenage: 7
  • Adult: 12
  • Insulin resistant adult: 25

See also OpenAPS documentation for SMB.

Enable AMA Autosense

Here, you can choose if you want to use the sensitivity detection ‘autosense’ or not.

Enable SMB

Here you can enable or completely disable SMB feature.

Enable SMB with COB

SMB is working when there is COB active.

Enable SMB with temp targets

SMB is working when there is a low or high temporary target active (eating soon, activity, hypo, custom)

Enable SMB with high temp targets

SMB is working when there is a high temporary target active (activity, hypo). This option can limit other SMB Settings, i.e. if ‘SMB with temp targets’ is enabled and ‘SMB with high temp targets’ is deactivated, SMB just works with low and not with high temp targets. It is the same for enabled SMB with COB: if ‘SMB with high temp target’ is deactivated, there is no SMB with high temp target even if COB is active.

Enable SMB always

SMB is working always (independent of COB, temp targets or boluses). For safety reasons, this option is just possibly for BG sources with a nice filtering system for noisy data. For now, it just works with a Dexcom G5, if using the Dexcom App (patched) or “native mode” in xDrip+. If a BG value has a too large deviation, the G5 doesn’t send it and waits for the next value in 5 minutes.

For other CGM/FGM like Freestyle Libre, ‘SMB always’ is deactivated until xDrip+ has a better noise smoothing plugin. You can find more here.

Enable SMB after carbs

SMB is working for 6h after carbohydrates , even if COB is at 0. For safety reasons, this option is just possibly for BG sources with a nice filtering system for noisy data. For now, it just works with a Dexcom G5, if using the Dexcom App (patched) or “native mode” in xDrip+. If a BG value has a too large deviation, the G5 doesn’t send it and waits for the next value in 5 minutes.

For other CGM/FGM like Freestyle Libre, ‘SMB always’ is deactivated until xDrip+ has a better noise smoothing plugin. You can find more information here.

Max minutes of basal to limit SMB to

This is an important safety setting. This value determines how much SMB can be given based on the amount of basal insulin in a given time, when it is not covered by COBs.

This makes the SMB more aggressive. For the beginning, you should start with the default value of 30 minutes. After some experience, you can increase the value with 15 minutes steps and watch how these changes are affecting.

It is recommended not to set the value higher than 90 minutes, as this would lead to a point where the algorithm might not be able to adjust a decreasing BG with 0 IE/h basal (‘zero-temp’). You should also set alarms, especially if you are still testing new settings, which warns you before running into hypos.

Default value: 30 min.

Enable UAM

With this option enabled, the SMB algorithm can recognize unannounced meals. This is helpful, if you forget to tell AndroidAPS about your carbs or estimate your carbs wrong and the amount of entered carbs is wrong or if a meal with lots of fat and protein has a longer duration than expected. Without any carb entry, UAM can recognize fast glucose increasments caused by carbs, adrenaline, etc, and tries to adjust it with SMBs. This also works the opposite way: if there is a fast glucose decreasement, it can stop SMBs earlier.

Therefore, UAM should always be activated when using SMB.

High temp-target raises sensitivity

If you have this option enabled, the insulin sensitivity will be increased while having a temporary target over 100 mg/dl or 5.6 mmol/l. This means, the ISF will rise while IC and basal will decrease.

Low temp-target lowers sensitivity

If you have this option enabled, the insulin sensitivity will be decreased while having a temporary target lower than 100 mg/dl or 5.6 mmol/l. This means, the ISF will decrease while IC and basal will rise.

Advanced Settings

Always use short average delta instead of simple data If you enable this feature, AndroidAPS uses the short average delta/blood glucose from the last 15 minutes, which is usually the average of the last three values. This helps AndroidAPS to work more steady with noisy data sources like xDrip+ and Libre.

Max daily safety multiplier This is an important safety limit. The default setting (which is unlikely to need adjusting) is 3. This means that AndroidAPS will never be allowed to set a temporary basal rate that is more than 3x the highest hourly basal rate programmed in a user’s pump, or, if enabled, determined by autotune. Example: if your highest basal rate is 1.0 U/h and max daily safety multiplier is 3, then AndroidAPS can set a maximum temporary basal rate of 3.0 U/h (= 3 x 1.0 U/h).

Default value: 3 (shouldn’t be changed unless you really need to and know, what you are doing)

Current Basal safety multiplier This is another important safety limit. The default setting (which is also unlikely to need adjusting) is 4. This means that AndroidAPS will never be allowed to set a temporary basal rate that is more than 4x the current hourly basal rate programmed in a user’s pump, or, if enabled, determined by autotune.

Default value: 4 (shouldn’t be changed unless you really need to and know, what you are doing)


Advanced Meal Assist (AMA)

AMA, the shortform of “advanced meal assist” is an OpenAPS feature from 2017 (oref0). OpenAPS Advanced Meal Assist (AMA) allows the system to high-temp more quickly after a meal bolus if you enter carbs reliably.

You will need to have completed objective 7 to use this feature

You can find more information in the OpenAPS documentation.

Max U/hr a Temp Basal can be set to (OpenAPS “max-basal”)

This safety setting helps AndroidAPS from ever being capable of giving a dangerously high basal rate and limits the temp basal rate to x U/h. It is advised to set this to something sensible. A good recommendation is to take the highest basal rate in your profile and multiply it by 4 and at least 3. For example, if the highest basal rate in your profile is 1.0 U/h you could multiply that by 4 to get a value of 4 U/h and set the 4 as your safety parameter.

You cannot chose any value: For safety reason, there is a ‘hard limit’, which depends on the patient age. The ‘hard limit’ for maxIOB is lower in AMA than in SMB. For children, the value is the lowest while for insulin resistant adults, it is the biggest.

The hardcoded parameters in AndroidAPS are:

  • Child: 2
  • Teenage: 5
  • Adult: 10
  • Insulin resistant adult: 12

Maximum basal IOB OpenAPS can deliver [U] (OpenAPS “max-iob”)

This parameter limits the maximum of basal IOB where AndroidAPS still works. If the IOB is higher, it stops giving additional basal insulin until the basal IOB is under the limit.

The default value is 2, but you should be rise this parameter slowly to see how much it affects you and which value fits best. It is different for anyone and also depends on the average total daily dose (TDD). For safety reason, there is a limit, which depends on the patient age . The ‘hard limit’ for maxIOB is lower in AMA than in SMB.

  • Child: 3
  • Teenage: 5
  • Adult: 7
  • Insulin resistant adult: 12

Enable AMA Autosense

Here, you can chose, if you want to use the sensitivity detection autosense or not.

Autosense adjust temp targets too

If you have this option enabled, autosense can adjust targets (next to basal, ISF and IC), too. This lets AndroidAPS work more ‘aggressive’ or not. The actual target might be reached faster with this.

Advanced Settings

Always use short average delta instead of simple data If you enable this feature, AndroidAPS uses the short average delta/blood glucose from the last 15 minutes, which is usually the average of the last three values. This helps AndroidAPS to work more steady with noisy data sources like xDrip+ and Libre.

Max daily safety multiplier This is an important safety limit. The default setting (which is unlikely to need adjusting) is 3. This means that AndroidAPS will never be allowed to set a temporary basal rate that is more than 3x the highest hourly basal rate programmed in a user’s pump, or, if enabled, determined by autotune. Example: if your highest basal rate is 1.0 U/h and max daily safety multiplier is 3, then AndroidAPS can set a maximum temporary basal rate of 3.0 U/h (= 3 x 1.0 U/h).

Default value: 3 (shouldn’t be changed unless you really need to and know, what you are doing)

Current Basal safety multiplier This is another important safety limit. The default setting (which is also unlikely to need adjusting) is 4. This means that AndroidAPS will never be allowed to set a temporary basal rate that is more than 4x the current hourly basal rate programmed in a user’s pump, or, if enabled, determined by autotune.

Default value: 4 (shouldn’t be changed unless you really need to and know, what you are doing)

Bolus snooze dia divisor The feature “bolus snooze” works after a meal bolus. AAPS doesn’t set low temporary basal rates after a meal in the period of the DIA divided by the “bolus snooze”-parameter. The default value is 2. That means with a DIA of 5h, the “bolus snooze” would be 5h : 2 = 2.5h long.

Default value: 2


Meal Assist (MA)

Max U/hr a Temp Basal can be set to (OpenAPS “max-basal”)

This safety setting helps AndroidAPS from ever being capable of giving a dangerously high basal rate and limits the temp basal rate to x U/h. It is advised to set this to something sensible. A good recommendation is to take the highest basal rate in your profile and multiply it by 4 and at least 3. For example, if the highest basal rate in your profile is 1.0 U/h you could multiply that by 4 to get a value of 4 U/h and set the 4 as your safety parameter.

You cannot chose any value: For safety reason, there is a ‘hard limit’, which depends on the patient age. The ‘hard limit’ for maxIOB is lower in MA than in SMB. For children, the value is the lowest while for insulin resistant adults, it is the biggest.

The hardcoded parameters in AndroidAPS are:

  • Child: 2
  • Teenage: 5
  • Adult: 10
  • Insulin resistant adult: 12

Maximum basal IOB OpenAPS can deliver [U] (OpenAPS “max-iob”)

This parameter limits the maximum of basal IOB where AndroidAPS still works. If the IOB is higher, it stops giving additional basal insulin until the basal IOB is under the limit.

The default value is 2, but you should be rise this parameter slowly to see how much it affects you and which value fits best. It is different for anyone and also depends on the average total daily dose (TDD). For safety reason, there is a limit, which depends on the patient age . The ‘hard limit’ for maxIOB is lower in MA than in SMB.

  • Child: 3
  • Teenage: 5
  • Adult: 7
  • Insulin resistant adult: 12

Advanced Settings

Always use short average delta instead of simple data If you enable this feature, AndroidAPS uses the short average delta/blood glucose from the last 15 minutes, which is usually the average of the last three values. This helps AndroidAPS to work more steady with noisy data sources like xDrip+ and Libre.

Bolus snooze dia divisor The feature “bolus snooze” works after a meal bolus. AAPS doesn’t set low temporary basal rates after a meal in the period of the DIA divided by the “bolus snooze”-parameter. The default value is 2.That means with a DIA of 5h, the “bolus snooze” would be 5h : 2 = 2.5h long.

Default value: 2