Diabetes Technology: CGMs and AID Systems
The last decade has seen a paradigm shift in diabetes management, moving from retrospective data (fingersticks and A1C) to real-time, actionable data via Continuous Glucose Monitors (CGMs), and automated interventions via smart insulin pumps.
Continuous Glucose Monitors (CGM)
A CGM consists of a small sensor inserted subcutaneously that measures interstitial glucose levels every 1 to 5 minutes. It transmits this data to a smartphone or receiver, providing a trend line, rate of change arrows, and customizable alarms for high and low blood sugars.
| Device | Wear Time | Calibration Required? | Notable Features |
|---|---|---|---|
| Dexcom G7 | 10 days | No | 30-min warmup, integrated transmitter, predictive low alerts. |
| FreeStyle Libre 3 | 14 days | No | Minute-by-minute streaming, smallest sensor size. |
| Medtronic Guardian 4 | 7 days | No (if used with 780G) | Integrates directly with Medtronic pump algorithms. |
| Eversense E3 | 6 months | Yes (daily) | Implantable sensor, on-body vibratory alerts. |
CGM data generated the concept of Time in Range (TIR), a metric defined as the percentage of time spent between 70 and 180 mg/dL. Clinical guidelines recommend a TIR of >70% for most adults with Type 1 and Type 2 diabetes.
Automated Insulin Delivery (AID) Systems
Often referred to as a "closed-loop" or "artificial pancreas," an AID system links a CGM with an insulin pump via an algorithm. The pump automatically adjusts basal insulin delivery—and in advanced systems, delivers auto-correction boluses—based on the CGM's predictive glucose values.
- Tandem t:slim X2 with Control-IQ: Adjusts basal delivery and gives automatic correction boluses.
- Omnipod 5: A tubeless patch pump that adjusts micro-boluses based on a customized glucose target.
- Medtronic MiniMed 780G: Features aggressive auto-corrections to handle missed meal boluses.
Even with AID, users must still announce meals and estimate carbohydrates. Ensure your Carb Ratios and Correction Factors are correctly programmed into the algorithm.
Common Technology Mistakes
- Sensor lag confusion: CGMs measure interstitial fluid, not blood. During rapid changes in glucose (after meals or exercise), the CGM will lag behind a capillary fingerstick by about 10-15 minutes.
- Alarm fatigue: Setting high and low alerts too tightly can result in constant alarms, leading the user to ignore them or disable the system entirely.
Frequently Asked Questions (FAQ)
- Can I wear these devices in an MRI or X-ray?
- No. Strong magnetic fields or radiation can destroy the electronics. They must be removed prior to MRI, CT scans, or diathermy.
- Do I still need to carry a standard blood glucose meter?
- Yes. A backup meter is essential for when symptoms do not match sensor readings, or during sensor warm-up periods.
Next Step: Estimate your daily insulin requirements with our Total Daily Dose Estimator.