Solo MicroPump Insulin Delivery System

The SOLO MicroPump Insulin Delivery System is a patch pump originally made by Medingo and purchased by Roche in 2010. Solo received FDA approval in 2009 and is expected to be available in 2012. The system has 4 parts: a micropump composed of reusable electronics plus an insulin reservoir, a remote, and a cradle.

The Cradle

Solo Cradle

The cradle takes the place of your standard infusion set. Insertion is easy with the SOLO inserter. The cradle attaches to to your body with an adhesive that holds it in place. It can be placed in any of the normal infusion sites such as your abdomen, buttocks, upper thighs and upper arms. After placing it where you want it, push one button on the inserter, the cannula is inserted and the cradle is ready for use. You can easily click the micropump in and out of the cradle to quickly attach and detach. This is particularly important since the pump is not waterproof. The pump site is changed regularly as you would a normal infusion site.

The Pump

Solo Cradle

The micropump is actually 2 parts that snap together, with a total size of 2.4 x 1.5 x 0.5 inches (6.1 x 3.8 x 1.3 cm). One part is a disposable 200 unit insulin reservoir. Changing it every 2 or 3 days is suggested, depending on your total daily dose of insulin. The reservoir is transparent so you can see how much insulin is left and view any potential site problems. It also holds the dispensing mechanism and a battery for the pump base. A separate device is used to refill the reservoir.

The pump base is the second part. It contains all of the brains of the pump: the electronics, memory, pump motor and a buzzer. It stores all your pump settings, including basal rate and bolus factors. It is designed to last 90 days before you need to change to a new one. You receive a spare in case of any problems with your main pump base. Tactile bolus buttons allow you to bolus from the pump on your body.

One advantage to Solo’s modular approach is that it is much greener. For example, with Omnipod, the entire patch pump is thrown away every 2 or 3 days. Each disposable pump has four 357 battery and a circuit board. This means every year, 119 to 178 circuit boards and 426 to 712 batteries are thrown in the trash (or recycled). This is largely eliminated with modular patch pumps. It also provides a significant economic advantage.

The Remote

Solo Cradle

The remote is about the size of a smartphone at 4.2 x 2.2 x 1.0 inches (10.6 x 5.6 x 2.5 cm). It has a color screen but keeps tactile buttons, unlike some of the newer patch pump controllers being developed that use touch screen interfaces similar to the smartphones on the market. You can input your settings with the remote and download them to the pump. Boluses can be given with the bolus buttons on the pump (what they call Bolus on Demand) or directly from the remote. Your pump settings in both places.

The remote also gives you access to other nice features. The bolus calculator, called the SOLO Bolus Guide, will help you figure out how much insulin to take for highs or meals and keep track of your Bolus on Board. You can also see a 90-day history including blood glucose trend graphs, average daily dose data and delivery details on the remote.

I’m curious how the communication between the two devices work, specifically if the information is passed back and forth between them automatically via syncing. For instance, if I bolus using the buttons on the pump while my remote is not near me, will that bolus information be passed on to the remote next time they are close enough to “speak?” If so, this allows graphing and record-keeping to remain accurate even if the remote is forgotten or misplaced.

Bolus Calculator

Unlike other pumps currently on the market, the Solo bolus calculator was designed to give the safest bolus doses possible. Bolus doses were determined as carb bolus plus correction bolus minus BOB. Roche’s other pumps use a complicated and less accurate bolus calculator based on the current glucose level where insulin stacking may occur. Hopefully, Roche will keep Solo’s safer bolus algorithm even though it differs from its other pumps.


Medingo has mentioned a “pay as you pump” feature in the past. There hasn’t been any more information released about it but it sounds like the upfront cost will be reduced. This may have more appeal to insurers and individuals who want to try this pump. The recurring fee would hopefully include ongoing costs like reordering supplies as well.

So where is it?

Already cleared by the FDA, Roche reports that the Solo should be available in the US in 2012. Let’s keep our fingers crossed.

Solo MicroPump Specifications
Solo MicroPump
Dimensions 2.4 x 1.5 x 0.5 inches (6.1 x 3.8 x 1.3 cm)
Weight with a full reservoir 0.85 oz (24 gr)
Pump base 3-month life after initial pairing
Occlusion & other safety alarms Audible on micropump
On-pump bolus buttons Can be customized and disabled
Detachable/re-attachable Yes, by disconnecting from cradle
Reservoir Capacity 200 units of U100 insulin (Min. 70 units)
Reservoir Description Transparent with volume fill lines
Reservoir Filling Device No syringe needed
Use Rapid Acting Insulins Humalog®, NovoLog®/ NovoRapid®, Apidra®
Reservoir Change Frequency 3 days NovoLog®/ NovoRapid®(based on insulin manufacturer labeling)
Cannula cradle infusion set
Cannula 9 mm, 90° insertion; soft Teflon®
Insertion needle 27 gauge; hidden from view
Automated inserter Virtually painless, auto-needle retraction
Adhesive Hypafix®- hypoallergenic, latex-free
Change frequency 2-3 days
Site change reminder Yes
Allows disconnection Yes
Dimensions 4.2 x 2.2 x 1.0 inches (10.6 x 5.6 x 2.5 cm)
Weight with batteries 5.2 oz (148 gr)
Batteries 2 AA alkaline
Guided procedures Start-up; reservoir replacement, micropump replacement, priming, Bolus Guide
Safety lock-out Auto keypad lock
Flexible programming Reminders and alerts
Remote screen Large, backlit, color graphics
Status bar and screen Current updates from micropump
Color panels Multiple (7) color choices
Remote notifications User-selected –audible, vibrate or both
Communication distance 5 feet (1.5 meters)
Soft keys User-selectable based on frequent use
Basal delivery options
Basal programs 7 programs; 30-minute segments
Unique graphic 24-hour format
Basal increment 0.05 unit per hour
Minimum basal rate 0.10 unit per hour
Maximum basal rate 30 units per hour
Temporary basal options Percentage or U/hr adjustment up to 24 hours
Bolus delivery options
Bolus types Normal, Long, Duo, Correction
2-way bolus Remote or micropump buttons
Bolus increment 0.05 unit
Minimum bolus 0.10 unit
Maximum bolus 30 units
Bolus on Board (BOB) Helps prevent insulin stacking; BOB includes carb and correction boluses as long as BG is entered; programmable 2-8 hours
Bolus Guide Suggests bolus based on carbs, current blood sugar, target blood sugar, boluses on board and personalized settings
Bolus Guide settings ranges
Insulin Sensitivity Factor (ISF) (also called Correction Factor) 10-400 mg/dL per unit of insulin
Settings can be done in 30 min segments
Insulin to Carbohydrate Ratio (ITC)
(also called Carb Factor)
3-150 grams of carb per unit of insulin
Settings can be done in 30 min segments
Blood glucose targets 70-200 mg/dL
Settings can be done in 30 min segments