Undelivered bolus alert on T-slim

I wanted to thank DrBB for his tip on extended bolus feature. I went from injections to the pump and have a lot of trouble controlling post meal spikes. So I just assumed I wanted the entire dose right away. I do pre dose 15m to30m before meal. The extended bolus feature works much better for me. I wish I could set it as default because it is easy to forget and skip over. Anyhow-Thanks DrBB

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You improve the chance of DrBB reading this is if you include this format: @DrBB.

I agree that the extended bolus on a pump is a magnificent tool to manage post-meal blood sugar levels. It works especially well when consuming meals with significant protein and fat components.

By the way, you might want to change the title of your post to better reflect its content. Just click on the pencil icon to the right of the title and then edit. Perhaps something like, “Good advice on the pump’s extended bolus” would work.


I use an old Paradigm 723 pump, so this may not be true for more current ones, but mine defaults to whichever bolus type you used last. So if I’ve done an extended one, the next one I do will come up on extended and that’s what I’ll get unless I switch to normal. And you’re welcome—glad it helped!

Unfortunately with Tandem, the extended bolus option is part of the regular bolus menu. I much preferred Medtronic where I selected the type of bolus I wanted to do before starting the bolus process. When I select an extended bolus with Tandem it is a huge number of button pushes to enter all the info. It was somewhat easier with Medtronic. There is no memory with Tandem as to the last extended bolus choices. It always starts as 50-50% with a 2-hour duration and you have to customize the choices.

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@fedd, here is a collection of information about EXTENDED BOLUSing taken from Tandem publications with a few of my editorial comments.

After scanning the comments of others, it seems the primary comments are not from Tandem users. I am a 20+ year Dexcom & pump user and have been on the Tandem CIQ technology (their word) since January 2020.

The way the Tandem pump is sequenced and without recall of things like last bolus choices is a SAFETY. Rarely would a pumper choose the same settings twice in a row for a bolus. Having a clean slate is thought to provide the pumper with a consistent pattern for selecting bolus options from the beginning.

The topic of UNDELIVERED BOLUS ALERT is a bit ponderous when the discussion is about extended bolus.

If you are really looking into the 11T Incomplete Bolus Alert or similar alarm, check Chapter 10 - Pump Reminders
Chapter 11 - User Settable Alerts and Alarms
Chapter 12 - Pump Alerts
Chapter 13 - Pump Alarms

CIQ User Guide (350+ pages and is best put on a tablet or computer for easier searching)


Here is what I have learned about extended bolusing.

Extended Bolus

DEFINITION: (from Tandem doc site) The Extended Bolus feature allows you to deliver part of the bolus now and part of the bolus slowly over a period of up to 8 hours (up to 2 hours if Control-IQ technology is turned on). This can be helpful for high-fat meals such as pizza or if you have gastroparesis (delayed stomach emptying).

DISCUSSION: Proteins and fats delay gastric (stomach) emptying into the small intestine. The small intestine is where most carbohydrates are absorbed into the blood stream with ‘heavy’ meals (Heavy meals here are high in fat, protein, or both, like pizza or lasagna).

The extended bolus helps by dividing the insulin given by the pump into a pattern most closely aligning with the individuals digestive pattern. Some individuals empty their stomachs faster than others while consuming the same meal. Because of these individual differences, experimentation or clinical evaluation must be used to determine the percentage for:

[a] pre-meal bolus and its lead time
[b] deliver now portion of the bolus
[c] deliver later portion of the bolus
[d] expected bolus when the up to 2 hour extended bolus has completed.

Administering an EXTENDED BOLUS ( from Tandem doc site)
When extending a bolus, any correction bolus amount will always be given in the DELIVER NOW portion. Talk with your healthcare provider to determine if this feature is appropriate for you, as well as for recommendations on the split between now and later and the duration for the later portion.

Deliver an extended bolus

  1. From the Home screen, tap BOLUS.

  2. Tap 0 grams (or 0 units).

  3. Using the on-screen keypad enter grams of carb (or units of insulin). Tap [check mark].

  4. If desired, tap Add BG and using the on-screen keypad enter a glucose value. Tap [check mark].

  5. Tap [check mark] to confirm the units of insulin to be delivered.

You can always tap View Calculation to display the Delivery Calculation screen.

  1. Confirm request.

· Tap [check mark] if entered data is correct.

· Tap to go back to make changes or view calculations.

  1. Tap EXTENDED to turn on the extended feature, then tap [check mark].

  2. Tap 50% under DELIVER NOW to adjust the percentage of the food bolus that is to be delivered immediately.

The percentage value for DELIVER LATER is automatically calculated by the pump. The default is 50% NOW and 50% LATER. The default for DURATION is 2 hours.

  1. Use the on-screen keypad to enter the percentage of the bolus to DELIVER NOW and tap [check mark].

For the DELIVER NOW portion, the minimum amount is .05 units. If the DELIVER NOW portion is less than .05 units, you will be notified and the DELIVER NOW portion will be set to .05 units.

The DELIVER LATER portion of the extended bolus also has minimum and maximum rates. If you program a DELIVER LATER rate outside of these limits, you are notified, and the duration of the DELIVER LATER portion is adjusted.

  1. Tap 2 hours under DURATION.

  2. Use the on-screen keypad to adjust the length of time the bolus is to be delivered, then tap [check mark].

  3. Tap “check mark”.

You can always tap View Units to display the breakdown of units to be delivered NOW versus LATER.

  1. Confirm request.

Tap “check mark” if entered data is correct.

Tap [ X ] to go back to make changes or view calculations.

  1. Tap “check mark”.

  2. The BOLUS INITIATED screen is temporarily displayed.

Only one extended bolus can be active at any given time. However, if the DELIVER LATER portion of an extended bolus is active, you can request another standard bolus.

  1. At the end of the EXTENDED BOLUS, you may need to enter a CORRECTION BOLUS to finish covering the carbohydrates consumed with the meal.

Hope this helps.