Can You Use Fiasp in a Tandem Mobi? User Friendly Guide

Introduction

If you’ve wondered, “Can you use Fiasp in a Tandem Mobi?“, you’re not alone. A lot of people with type 1 diabetes or type 2 diabetes are seeking faster, more convenient insulin delivery—especially when using advanced diabetes technology like CGM monitors.

Fiasp is becoming more popular as a rapid-acting insulin due to its very high rate of absorption and better control of blood sugar levels after meals. But is it safe to use with the Tandem Mobi insulin pump, particularly when used with systems such as Dexcom G6? This article explores the science, safety, and real-world use of Fiasp insulin delivered through pumps like the Tandem Mobi system.

What is Fiasp Insulin?

Let us first understand what Fiasp insulin is. Fiasp (Faster Insulin Aspart) is a faster-acting analogue of NovoLog insulin, and it was developed by Novo Nordisk. It was designed to be absorbed more quickly into the body.

What Makes Fiasp Work Faster?

It contains two additives:

• Niacinamide (Vitamin B3) – helps speed up insulin absorption
• L-arginine – keeps the insulin stable in solution

Thanks to these, Fiasp insulin begins working in about 2.5 minutes, which is significantly faster than most rapid-acting insulins used in diabetes care.

Available Forms of Fiasp

• 10 mL vials
• 3 mL FlexTouch pens
• 3 mL PenFill cartridges
• 1.6 mL PumpCart (specifically designed for insulin pumps)

Tandem Mobi Insulin Pump Overview

Tandem Diabetes Care is gladly introducing the new Tandem Mobi. It’s compact, discreet, and controlled by smartphone—making it one of the most user-friendly insulin pump systems available.

Key Features of Tandem Mobi

• App-based insulin dosing via smartphone
• Uses Control-IQ technology for automated insulin delivery
• Fully integrates with the Dexcom G6 CGM monitor
• Waterproof, rechargeable, and wearable with or without tubing

Together with CGM integration, Tandem Mobi supports closed-loop insulin delivery, optimising glucose control in real-time.

Tandem Mobi Compatible Insulins

In case you’re wondering, “What insulins can be used with Tandem Mobi?” here’s the official answer:

• Humalog (insulin lispro) 
• NovoLog (insulin aspart) 

At this time, these are the only insulins approved for use with Tandem insulin pumps. This means that using Fiasp with Tandem pump models, including the Mobi, would be considered off-label use. 

• Void your pump warranty
• Affect insulin stability
• Disturb CGM-integrated insulin delivery

Is Fiasp Safe in Tandem Pump Systems?

So, can you use Fiasp in a Tandem Mobi safely? Technically yes—but with important warnings.

Reported Risks of Using Fiasp in Tandem Pumps:

• Reservoir clogs
• Irritation at the infusion site
• Unpredictable absorption of insulin
• More frequent need to change infusion sets (every 2–3 days)

Since Control-IQ technology relies on continuous insulin delivery, these matters might disrupt the performance of the Tandem Mobi + Dexcom G6 system.

Why Some Users Prefer Fiasp in Insulin Pumps

Despite the risks, some users still prefer Fiasp insulin, especially those with:

• Irregular meal schedules
• Post-meal glucose spikes
• The need for more flexible dosing

Top Benefits of Fiasp in Pump Therapy

• Ultra-fast onset (~2.5 minutes)
• Better postprandial glucose control
• Can be dosed after meals if needed
• May remain stable in reservoirs for up to 6 days

These advantages appeal to users looking for greater flexibility and tighter blood sugar control.

Fiasp vs Humalog for Pump Therapy

Here’s a comparison between Fiasp and Humalog when used in insulin pumps:

Feature	Fiasp	Humalog
Onset Time	~2.5 minutes	~10–15 minutes
Tandem Approval	No	Yes
Reservoir Stability	4–6 days	Up to 6 days
CGM Compatibility	Variable	Highly stable

While Fiasp works faster, Humalog remains more reliable in the Tandem Mobi system, particularly when used with CGM monitors.

How Tandem Mobi Works with Fast-Acting Insulin

Tandem Mobi is designed specifically for fast-acting insulins, which are contained within the pump. It utilises measurement data from Dexcom G6 CGM along with Control-IQ algorithms to modulate insulin delivery every few minutes.

The unpredictability of insulin behavior—as experienced with Fiasp from time to time, might make the pump deliver insulin incorrectly, which may destabilise blood sugar levels.

For safety and consistency, Tandem recommends sticking with Humalog or NovoLog.

Changing Insulin Types in Tandem Mobi

If you’re thinking of switching to Fiasp insulin, here are the important steps to follow:

• Talk to your endocrinologist or diabetes health worker
• Monitor glucose closely using your CGM monitor
• Be aware of potential warranty limitations
• Watch for signs of infusion set failure
• Always keep backup insulin, like Humalog or NovoLog, on hand

Tips for Using Fiasp in Insulin Pumps

If you do choose to try Fiasp in your Tandem Mobi, follow these safety tips:

• Change infusion sets every 2–3 days
• Watch CGM data for erratic trends
• Avoid using Fiasp in high-temperature settings
• Use metal cannulas to reduce clogging
• Carry backup insulin and manual delivery options

Comparing Fiasp with Other Fast Insulins

Insulin	Onset	Tandem Approved?	Notes
Fiasp	~2.5 min	No	Fastest acting, but unstable in pumps
Humalog	~10 min	Yes	Most reliable for CGM integration
NovoLog	~10–15 min	Yes	Consistent with Control-IQ
Apidra	~15 min	Limited	Less commonly used in pump systems

How Much Does Fiasp Cost?

The price of Fiasp insulin depends on insurance and your location. On average:

• $69 for a 1.6 mL PumpCart
• Manufacturer discounts and coupons may be available
• Ask about CGM bundle deals or pharmacy benefits for additional savings

Conclusion

So, can you use Fiasp in a Tandem Mobi? The technical answer is no. Fiasp insulin is not compatible with Tandem Mobi insulin pumps. Tandem pumps are specifically approved for use with Humalog and Novolog U-100 insulins. Although Fiasp is a fast-acting insulin analogue, its unique onset and action profile have not been tested or approved for use with Tandem devices. Using Fiasp in a Tandem pump could affect the pump’s performance and may potentially void the device’s warranty.

Always consult your healthcare provider before switching insulin types and make safety your top priority.