IOB stands for Insulin on Board, and it represents the amount of insulin still actively working in your body from recent doses. On the Omnipod, this number appears on your lock screen, the status bar, and the Dashboard tab of your home screen. It tells you how many units of insulin are still lowering your blood sugar, so you can avoid giving yourself too much when it’s time for your next dose.
Why IOB Matters
Rapid-acting insulin doesn’t work all at once. After you deliver a bolus, that insulin continues lowering your blood sugar for several hours. If you see a high reading 90 minutes after eating and immediately give a full correction dose, you’re stacking new insulin on top of insulin that hasn’t finished its job yet. This “insulin stacking” is one of the most common causes of unexpected low blood sugar events.
IOB exists to prevent that. Your Omnipod tracks how much glucose-lowering power remains from previous boluses and factors it into the next suggested dose. You can also use it on your own: glancing at your IOB alongside your continuous glucose monitor reading gives you a quick sense of whether your blood sugar is likely to keep dropping, hold steady, or rise.
Where to Find IOB on the Omnipod 5
The Omnipod 5 displays IOB in several places so you rarely have to dig for it:
- Lock screen: The IOB value appears before you even unlock the controller.
- Status bar: An icon at the top of the screen shows the system mode and current IOB while in Automated Mode.
- Dashboard tab: The home screen’s Dashboard section lists “Insulin on Board” with the current value whenever IOB data is available.
- During a bolus: While insulin is being delivered, the last bolus information is replaced by a live IOB estimate.
How the Omnipod Calculates IOB
This is where it gets a little more nuanced than a simple countdown. The Omnipod 5 actually tracks IOB from two separate sources, and it handles each one differently.
For boluses you deliver yourself (meal boluses and correction boluses), the system uses your Duration of Insulin Action (DIA) setting. This is the number of hours you or your healthcare team programmed into the device to represent how long a bolus stays active. The system gradually decreases the IOB from that bolus over the DIA window until it reaches zero.
For insulin delivered automatically by the algorithm in Automated Mode, the system uses its own internal method to calculate IOB. Your DIA setting does not influence this calculation at all. In Automated Mode, the Omnipod 5 algorithm reads your CGM data every 5 minutes and delivers small microboluses every 5 minutes based on your current and predicted glucose levels, aiming for your set target (which you can customize between 110 and 150 mg/dL). When the algorithm ramps up insulin delivery to handle a high reading, that extra insulin gets added to your total IOB.
This matters because the IOB number you see on screen reflects both sources combined. If the algorithm has been delivering extra insulin to bring down a high, that insulin will be subtracted from your next manual bolus. So if you go to bolus for a meal and notice the suggested dose seems lower than expected, the algorithm’s recent automated deliveries are likely the reason.
How IOB Affects Your Bolus Suggestions
When you use the Omnipod’s bolus calculator, the system applies specific rules about when IOB gets subtracted from a suggested dose. Understanding these rules helps you make sense of the numbers you see.
Correction IOB (insulin still working from a previous correction dose) gets subtracted from both meal boluses and correction boluses. This makes sense: if insulin is already working to bring your blood sugar down, you need less of a correction regardless of whether you’re also eating.
Meal IOB (insulin still working from a previous meal dose) only gets subtracted from correction boluses, not from new meal boluses. The logic here is that meal insulin was matched to carbs you already ate, so it shouldn’t reduce the insulin calculated for new carbs you’re about to eat. It should, however, reduce a correction because it’s still pulling your blood sugar down.
There’s one important detail: if you enter carbs or a bolus amount without also entering a glucose value, the system will not subtract IOB from the suggestion. It can’t adjust for active insulin if it doesn’t know where your blood sugar currently stands. If you want the calculator to account for IOB, enter a glucose reading.
Why Your DIA Setting Matters
The Duration of Insulin Action setting directly controls how quickly your IOB from manual boluses counts down to zero. If it’s set too short, the system will “forget” about active insulin too soon, and you’ll get larger correction suggestions than you actually need. The result is insulin stacking by another name, and it leads to lows that can be hard to explain.
Research in the Journal of Diabetes Science and Technology found that using an inappropriately short DIA is a widespread problem, causing unrecognized insulin stacking and unexplained hypoglycemic episodes. Making things worse, the resulting lows often get blamed on other settings like basal rates or carb ratios, leading to further adjustments that compound the problem. Most rapid-acting insulin analogs stay active for longer than many users assume, so if you’re experiencing frequent unexplained lows, a DIA that’s set too short is worth discussing with your care team.
Automated Mode vs. Manual Mode
In Manual Mode, IOB is straightforward: it reflects only the boluses you’ve given yourself, and it decays according to your DIA setting.
In Automated Mode, the picture is more complex. The algorithm continuously adjusts insulin delivery using your total daily insulin as a baseline. It can increase delivery when glucose is rising and decrease it when glucose is falling. All of that automated insulin feeds into your IOB total. The algorithm also uses your IOB when deciding how much automated insulin to deliver next, creating a feedback loop designed to keep you near your target. This is why the IOB number in Automated Mode can sometimes seem higher or change more frequently than you’d expect from your manual boluses alone.