Control-IQ™ technology is a feature of the Tandem t:slim X2™ pump that automatically adjusts insulin delivery rates and amounts in response to readings from a continuous glucose monitoring system (CGM). The pump can be used with or without Control-IQ technology enabled.

Indications

The Control-IQ technology is approved for use from 6 years of age, when daily insulin requirements are between 10 and 100 IU and when body weight is between 25 and 140 kg. It can be used with any rapid insulin analog (glulisine, lispro or aspart) but cannot be used with ultrafast insulin analogs (e.g., fast aspart). Currently, its use is contraindicated in pregnant women, patients on hemodialysis or those using hydroxyurea.

Components

Tandem t:slim X2™ with Control-IQ technology comprises a t:slim X2™ insulin pump (Tandem Diabetes Care, San Diego, CA) with an embedded model-based predictive algorithm, integrated with the Dexcom G6 continuous glucose monitoring system (Dexcom, San Diego, CA), which does not require calibration. The t:slim X2™ insulin pump with color touch screen is smaller than other pumps and holds 300 UI of insulin. This pump is waterproof (tested at 0.91 m for 30 min) and rechargeable via a micro-USB port, and its software can be updated remotely (see Fig. 1).

Fig. 1

Schematic representation of the components of the Tandem t:slim X2™ with Control-IQ technology

Modes

Algorithm action Control-IQ technology uses CGM and delivers insulin data to predict glucose levels 30 min ahead and adjust insulin delivery every 5 min accordingly, including automatic correction boluses.

The system has three different modes with some differences regarding the operation of the algorithm (see Table 2):

In the standard mode, the aim of the algorithm is to maintain glucose levels between 112.5 and 160 mg/dl (6.24 and 8.88 mmol/l). When the predicted glucose value is within the target range, the pump will deliver insulin at the rate determined by the active personal profile settings. If sensor glucose values are predicted to exceed 160 mg/dl (8.88 mmol/l), basal insulin is increased, whereas if sensor glucose values are predicted to be > 180 mg/dl (10 mmol/l), the system delivers an automatic correction bolus with a target of 110 mg/dl (6.11 mmol/l). If the prediction is that the glucose value falls below 112.5 mg/dl (6.24 mmol/l), basal insulin is decreased, and when the prediction is that glucose values fall below 70 mg/dl (3.89 mmol/l), insulin infusion is interrupted, resuming progressively when the prediction is that glucose will exceed the value of 70 mg/dl (3.89 mmol/l).

In the sleep activity mode, the aim of the algorithm is to maintain glucose levels between 112.5 and 120 mg/dl (6.24 and 6.66 mmol/l). When the predicted glucose value is within the target range, the pump will deliver insulin at the rate determined by the active personal profile settings. If sensor glucose values are predicted to exceed 120 mg/dl (6.66 mmol/l), basal insulin is increased. In this mode, no automatic correction boluses are delivered. It is recommended to use it systematically, provided that the expected duration of sleep is > 5 h. It can be activated manually or can be programmed (two sleep times are available), and in this case it is automatically deactivated at the end of the period.

In the exercise mode, the aim of the algorithm is to maintain glucose levels between 140 and 160 mg/dl (7.77–8.88 mmol/l). When the predicted glucose value is within the target range, the pump will deliver insulin at the rate determined by the active personal profile settings. When the prediction is that glucose will exceed 160 mg/dl (8.88 mmol/l), the basal infusion is increased, and when the prediction is that it will exceed 180 mg/dl (10 mmol/l), self-correcting boluses will be administered with a glucose target of 110 mg/dl (6.11 mmol/l). The basal infusion is reduced when a glucose value < 140 mg/dl (7.77 mmol/l) is predicted and stopped when the glucose value of 80 mg/dl (4.44 mmol/l) is predicted to be reached. This mode must be turned on and off manually. It is recommended to start it 60–90 min before exercising.

Table 2 Operation of the three modes available in Tandem t:slim X2™ with Control-IQ technologyAutomated Correction Boluses

In the standard and exercise modes, automated correction boluses are delivered only when the maximum basal rate is achieved. The maximum insulin delivery rate is a calculated value dependent on an individual’s correction factor (CF) setting (in the active personal profile), total daily insulin estimated by Control-IQ technology based on actual total daily insulin values and current insulin on board (IOB). The total daily insulin value may be updated if there is an important discrepancy between the programmed value and that used for the system. According to that calculation, basal insulin infusion will never exceed 15 IU/h nor will it exceed 50% of the total daily insulin dose in the last 2 h. The amount of the correction bolus is 60% of the calculation based on glucose value and the correction factor (CF) in that period of time. Furthermore, the system does not administer an automatic correction bolus until 1 h after a previous bolus (both meal bolus and self-correction bolus). For an extended bolus, these 60 min do not start until the bolus has been fully delivered.

Required Personal Profile Settings

To use Control-IQ technology, the following personal profile settings must be configured:

In addition to the required personal profile settings, there are two values specific to Control-IQ technology that must be set. These are:

Weight

Total daily insulin

Once Control-IQ has been activated, the glucose target is set at 110 mg/dl (6.1 mmol/l) and the duration of active insulin at 5 h. In the event that the system exits Control-IQ, the pump will deliver insulin according to the programmed basal rate, glucose target and insulin duration.

Table 3 shows the main settings and their configuration ranges both when the system is working with Control-IQ technology and when there is an exit from automatic mode.

Table 3 Main settings of the Tandem t:slim X2™ with Control-IQ and settings of the Tandem t:slim X2 pumpCustom Settings

The system allows the patient to create up to six personal profiles (basal rate, ICR and CF) to better adapt to different situations in which insulin requirements vary (work shifts, menstrual period, illness or stress, sports, etc.). To improve the effectiveness of the system, adequate adjustment of the three personal profile components is essential.

Boluses

The Control-IQ technology allows administering manual and extended boluses (15 min–2 h). While an extended bolus is being delivered, the system may increase the basal insulin infusion. When Control-IQ technology sets the basal rate to 0 units per hour, due to prediction of a glucose value below range, bolus deliveries will continue. This includes starting a new bolus and any remaining bolus from an extended bolus delivery.

Switch to Programmed Personal Profile

If the CGM connection is lost or stopped for ≥ 20 min, the pump returns to the active personal profile settings until the connection has been restored. Once restored, Control-IQ will resume automatically.

Alerts

The system can display different alerts and alarms on the pump screen, which are accompanied by different sounds and recommendations for their solution.

Table 4 shows a summary of the main alerts and alarms.

Table 4 Main alarms and alerts of the Tandem t:slim X2™ with Control-IQ