Two very different pumps. One algorithm. Both run Control-IQ+ — the only AID system with an 8-hour extended bolus during automation, a dedicated Sleep Activity mode, and AutoBolus for missed meals.
Device specifications change frequently — always verify current information directly with the manufacturer before making any decisions. Full disclaimer.
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Tandem makes two pumps — the t:slim X2 and the Mobi — and both run the same Control-IQ+ algorithm. The algorithm is where the clinical work happens: a 30-minute glucose prediction engine that adjusts basal every 5 minutes, delivers automated correction boluses, and has unique modes for sleep and exercise. The choice between pumps is about hardware fit, not performance.
Tandem Diabetes Care is a current Juicebox Podcast sponsor. The Algorithm Pumping series covers Control-IQ in real-world use: Episode #1171 — Pump & CGM Overview Part 2 · Full series at juiceboxpodcast.com → Series → Algorithm Pumping
The Mobi has no screen. All settings, boluses, and status are managed through the Tandem t:slim mobile app on a compatible iPhone (iOS). An Android app received FDA approval and is launching in 2026. There is one physical button on the pump for bolusing if your phone isn't handy.
The Mobi fits in a coin pocket. It can be worn on the body with an adhesive sleeve (sold separately), clipped to clothing, or slipped into a pocket. The 5-inch tubing option — exclusive to Mobi — minimizes the tubing between pump and infusion site.
Rated IP28 — tested at 8 feet for 2 hours. You can swim with the Mobi. The t:slim X2 is not waterproof (watertight only — no swimming or hot tubs). For patients who are active in water, Mobi is the only Tandem option.
When paired with the standard Dexcom G7 (10-day), you can view glucose data and deliver boluses directly from Apple Watch — without picking up your phone. Not available with G6.
CGM limitation: Mobi works with Dexcom G6 and standard Dexcom G7 (10-day) only. It does not support FreeStyle Libre 3 Plus. If your patient uses or prefers Libre, the t:slim X2 is the correct pump.
The t:slim X2 has a full color touchscreen on the pump itself — you can bolus, check status, and adjust settings directly on the device without a phone. The app (iOS + Android) provides additional control and data viewing.
50% more reservoir capacity than the Mobi's 200 units. Meaningful for patients with higher insulin requirements. Both pumps use 3-day infusion set changes.
Works with Dexcom G6, Dexcom G7, and FreeStyle Libre 3 Plus (early access rolled out late 2025). The only Tandem pump compatible with Libre — and the only AID system except twiist to support both Dexcom and Libre in the U.S.
Rechargeable via USB — approximately 5 days per charge. Charges quickly. Uses a standard cable. Note: the t:slim X2 is watertight (IPX7, 3 feet, 30 minutes) but not waterproof — no swimming or hot tub use.
Control-IQ+ looks 30 minutes ahead using CGM data. If glucose is predicted above 160 mg/dL, basal increases. If predicted above 180 mg/dL, an AutoBolus fires. If trending low, basal decreases or suspends.
If glucose is predicted to rise above 180 mg/dL, the algorithm calculates a correction bolus targeting 110 mg/dL and delivers 60% of it — automatically, up to once per hour. This covers missed or underestimated meal boluses.
The only AID system with a dedicated Sleep Activity setting. At night it targets 112.5–120 mg/dL — more aggressive than the default day target. Real-world data shows 90% overnight TIR with Sleep Activity active.
Raises the treatment target to 140–160 mg/dL to reduce hypoglycemia risk during activity. Set before exercise, return to default after. Available on both pumps.
Patient wants the smallest possible pump. Active in water (swimming). Comfortable with phone-only control. Uses Dexcom G6 or G7. Wants Apple Watch bolus capability. Android users — note Android app launching 2026.
Patient prefers on-pump screen control. Higher insulin needs (300-unit reservoir). Uses or prefers FreeStyle Libre 3 Plus. Uses Android now. Patient not comfortable relying on phone for all pump functions.
Control-IQ+ algorithm. AutoBolus. Sleep Activity (90% overnight TIR). Exercise Activity. 8-hour extended bolus in automation. Temp Basal 0–250% in automation. 3-day infusion set changes. 4-year warranty. Tandem Source data platform.
Control-IQ+ launched March 2025 as a free remote software update for all eligible in-warranty Tandem customers. This means patients on older Control-IQ hardware can access the new algorithm without buying new hardware — verify eligibility at tandemdiabetes.com.
Control-IQ+ introduced three features that no other AID system has: an 8-hour extended bolus during automation, a Temp Basal rate while automation is active, and a dedicated Sleep Activity mode with real-world 90% overnight TIR data. Here's how to use each one.
The New Features in Control-IQ+| Feature | Tandem Mobi | t:slim X2 |
|---|---|---|
| Screen | None — phone only | Color touchscreen |
| Reservoir | 200 units | 300 units |
| Waterproof | Yes — IP28 (8 ft, 2 hrs) | No (watertight only) |
| CGM support | Dexcom G6/G7 only | Dexcom G6/G7 + Libre 3 Plus |
| Android app | 2026 | Available now |
| Wireless charging | Yes | No (USB cable) |
| Tubing option | 5" or standard | Standard only |
| Apple Watch bolus | Yes (with G7) | No |
| Size | Coin-pocket small | Traditional pump size |
| Wear options | Pocket / clip / sleeve / on-body | Pocket / clip |
| Algorithm | Control-IQ+ — identical on both | |
The most common missed optimization. Patients often don't realize it doesn't activate automatically. Confirm it's enabled and scheduled for sleep hours. Real-world data: 90% overnight TIR with Sleep Activity — compared to ~70% overall TIR in the pivotal trial.
Confirm patient is running Control-IQ+ (not the original Control-IQ). Key new features they may be missing: Extended Bolus up to 8 hours, Temp Basal during automation, expanded age/weight indications. Update via Tandem Source app.
Many patients don't know about the 8-hour extended bolus or don't understand when to use it. Counsel specifically for high-fat, high-protein meals. Common use cases: pizza, Chinese takeout, restaurant meals, holiday dinners.
Pull reports via Tandem Source (clinic platform). Review: TIR breakdown, Sleep Activity TIR vs daytime TIR, AutoBolus frequency (high AutoBolus = patient often missing meal boluses), Temp Basal usage.
Control-IQ has one of the deepest published evidence bases of any AID algorithm — pivotal trial data, real-world studies, and the first NEJM-published AID trial in type 2 diabetes. Here's what the science actually says.
Clinical EvidenceThe benefits of AID are proven — better sleep, fewer adverse events, better glucose control. Any one of these outcomes can be life-changing for children living with diabetes and their families.
— Dr. Paul Wadwa, Director, Pediatric Clinic, Barbara Davis Center for Diabetes · University of Colorado · via Tandem Control-IQ+ Launch Press Release (March 2025)The C|A|R|E|S Framework from the PANTHER Program. Applies to both t:slim X2 and Tandem Mobi — hardware differences noted where relevant.
30-min predictive algorithm. Adjusts basal every 5 min. AutoBolus: 60% of calculated correction, target 110 mg/dL, up to 1×/hour when predicted >180 mg/dL. Sleep Activity: targets 112.5–120 mg/dL. Exercise Activity: targets 140–160 mg/dL. Increases basal when predicted >160 mg/dL.
Basal rates, I:C ratio, ISF, Active Insulin Time all programmed by user. NEW in Control-IQ+: Temp Basal 0–250% up to 72 hrs during automation; Extended Bolus up to 8 hours during automation (only AID system). Activity modes: Sleep / Exercise. Cannot adjust correction target (fixed at 110 mg/dL for AutoBolus).
Automation can be turned off manually; pump operates with basal rates and standard bolus calculator. CGM signal loss pauses automated adjustments — pump continues basal. If cartridge swapped mid-extended-bolus, extended bolus cancels. Activity modes must be set manually — Sleep does not auto-activate at bedtime.
Always bolus for meals — AutoBolus supplements but doesn't replace meal boluses. Enable Sleep Activity every night for best overnight TIR. Use Extended Bolus for high-fat/protein meals. Temp Basal for exercise/illness. Cartridge changes: complete before starting extended bolus. Confirm software update to Control-IQ+ (free).
Mobi: Dexcom G6, standard G7 (10-day) only. t:slim X2: Dexcom G6, G7, FreeStyle Libre 3 Plus (rolling). Caregiver follow: Available via Dexcom Follow; Libre 3 Plus on t:slim limits caregiver sharing simultaneously. Data: Tandem Source platform (clinic + patient). Apple Watch bolus: Mobi + standard G7 only.
Pivotal trial (Buckingham et al.): TIR 70% vs 59% (+2.6 hrs/day), A1C −0.3%. Real-world (Beck et al., 2023): 9,000 users, TIR >10% increase within 2 weeks, 74% TIR at 12 months. Sleep Activity: 90% overnight TIR (real-world). T2D (Kudva et al., NEJM 2025): TIR +24% (48%→64%), A1C −0.9% at 13 weeks.
Source: PANTHER Program · Barbara Davis Center · University of Colorado · Tandem Diabetes Care product documentation · Published clinical literature