4 - Diabetes Technoloy: Blood Glucose Meters, CGMs, and Pumps

What are the three main components of a blood glucose monitoring system?

Glucose meter

Lancet/lancing device

Test strips

How to use a blood glucose meter?

1. Prepare your supplies and clean your hands

2. Turn on glucometer and insert test strip

3. Prick your finger squeeze a drop of blood

4. Place the drop to the edge of the test strip

5. Wipe away any remaining blood

When should people with diabetes check blood glucose using BGM according to ADA 2026?

People using insulin should check as appropriate: fasting, before/after meals, bedtime, overnight, around exercise, when hypo-/hyperglycemia is suspected, and before/during critical tasks like driving

CGM users must also have access to a BGM device

Common error blood glucose meters considerations?

Damaged test strip

Incorrect test strip insertion

Not enough blood

Lancing device too shallow

What if a patient complains "It hurts to poke my finger” ?

Use a fresh lancet

Change the gauge (thickness) of your lancet

Adjust the setting on your lancing device

Alternate the finger or spot on your finger where you are poking

What is continuous glucose monitoring (CGM)?

Gives updated glucose value every 1 – 5 minutes by measuring glucose in the interstitial tissue

Includes up to 3 components →

• Transmitter

• Sensor

• Receiver/reader

How accurate are blood glucose meters (BGM) and continuous glucose monitors (CGM)?

BGM → Within 15–20% of lab values 95–99% of the time

CGM → Within 20 mg/dL or 20% of BGM readings

Who eligible for CGM?

Diagnosis of diabetes (T1D, T2D, GDM) and 2+ years old

Insulin use → medicare/medicaid any insulin

Hypoglycemia → recurrent BG <55mg/dL or BG <55mg/dL and needing assistance

Anyone who is capable of using the device safely either by themselves or with a caregiver

Who should use CGM according to ADA 2026, and when is it recommended during pregnancy?

CGM is recommended at diagnosis and anytime thereafter for people with diabetes using insulin, hypoglycemia-causing medications, or treatments where CGM helps management

It helps pregnant individuals with T1D meet glucose and A1C goals and may benefit other diabetes types during pregnancy

What are the three types of CGM, and how do they differ?

Professional → Clinic-owned, blinded or real-time.

Personal → Prescription required, real-time

Over-the-counter (OTC) → No prescription, real-time

Examples of OTC CGM?

Dexcom Stelo

Abbott Lingo

Libre Rio

Examples of Professional CGM?

Dexcom G6 Pro

Example of Personal CGM?

Dexcom G6/G7

Libre 2+/3+

Eversense

Simplera

Dexcom G6?

Pump integration → Tslim, Mobi, Omnipod 5, iLet

Max wear time → 10 days

Warm-up time → 2 hour

Transmitter → 3 months

Optional calibrations

FDA approved in 2+

Dexcom G7 10 day?

Pump integration → Tslim, Mobi, Omnipod 5, iLet

Max wear time → 10 days plus 12 hour grace period

Warm-up time → 0.5 hours

Disposable transmitter

Optional calibrations

FDA approved in 2+

Approved in pregnancy!!

Dexcom G7 15 day?

Pump integration → Tslim, Omnipod 5, iLet

Max wear time → 15 days plus 12 hour grace period

Warm up time → 1 hour

Transmitter → 3 months

Disposable transmitter

Optional calibrations

FDA approved in 18

Approved in pregnancy!!

Libre 2+ and Libre 3+?

Pump integration → Tsilm, Omnipod 5, iLet, Twilst

Max wear time → 15 days

Warm up time → 1 hour

Disposable transmitter

No calibrations

FDA approved in 2+

Approved in pregnancy!!

Eversense?

Pump integration → Twiist, coming soon iLet

Max wear time → 365 days

Warm up time → 24 hours

Charge transmitter daily

After 14 days, weekly calibrations

FDA approved in 18+

Simplera?

Pump integration → 780G Flex in-pen (smart insulin pen)

Max wear time → 7 days

Warm up time → 2 hours

Charge transmitter weekly

Optional calibrations

FDA approved in 7+

Application issues with CGMs?

Apply to flat, clean, dry area; avoid excessive hair

Secure adhesive after application

Use overlay patches if needed

Contact dermatitis from adhesive → Rotate sites, can try pretreating with fluticasone nasal spray on skin

What can cause false highs in CGMs?

Vitamin C >1000mg (Libre 2+/3+)

Acetaminophen >4gm/day (Dexcom, Simplera (any dose)

Dehydration

What can cause false lows in CGMs?

Hydroxyurea (Dexcom, Simplera)

“Compression lows” → Due to physical pressure on the CGM, usually during sleep

How can faulty sensors affect CGMs?

May error/stop early or read falsely low

Advantages of CGMs?

More accurate picture of glucose throughout day and night

Can assess glycemic patterns and glycemic variability

Can potentially prevent hypo- and hyperglycemia

Integration with insulin pumps

Can share glucose readings with family and healthcare team

Disadvantages of CGMs?

Higher cost

Insurance coverage can be difficult

Information overload

Alert fatigue

Constant presence of sensor on skin

Skin irritation

How is CGM insurance coverage typically billed, and where are orders sent?

Medicare/Medicaid → Medical benefits → Send order to DME supplier

Commercial insurance → Pharmacy benefits → Send prescription to pharmacy or DME supplier that bills pharmacy benefits

Coverage is subject to deductibles and copays

What data is gathered by a CGM?

Time in Range (TIR) → Goal >70 % between 70-180 mg/dL

Average Glucose

Glucose Management Indicator → ~ A1c, goal < 7%

Glucose Variability (% coefficient of variation) → Goal < 1/3 of average glucose

What is an insulin pump?

A wearable medical device that supplies a continuous flow of rapid acting insulin underneath the skin

Are an alternative to multiple daily injection (MDI) insulin therapy

What are the three components of an Automated Insulin Delivery (AID) system, and what does each do?

CGM → Measures glucose continuously

Algorithm → Determines insulin delivery needs

Insulin pump → Delivers insulin based on the algorithm's instructions

How does an AID system work?

An insulin pump mimics how your pancreas would naturally release insulin → basal and bolus insulin

Basal insulin?

Small, continuous rate of rapid-acting insulin → multiple basal rates are common

All pumps have the ability to automatically adjust basal rates based on glucose levels from a connected CGM

Bolus insulin?

Manual surges of rapid-acting insulin when eating/correct high blood glucose

The pump uses the information you enter about your carb intake to calculate the bolus dose

What is the insulin-to-carbohydrate ratio (ICR)?

Number of grams of carbohydrates covered by 1 unit of insulin

What is the Rule of 500?

500 ÷ total daily insulin dose (TDD) = grams of carbohydrates covered by 1 unit of insulin

What is the insulin sensitivity factor (ISF)?

The amount (mg/dL) that 1 unit of insulin lowers blood glucose

What is the Rule of 1700?

1700 ÷ total daily insulin dose (TDD) = estimated ISF (mg/dL per unit)

Common insulin pump setting?

Insulin to carb ratio → ICR

Insulin sensitivity factor → ISF

Basal rates

Advantages of insulin pumps?

Adjustable insulin delivery with a variety of settings

Merge insulin delivery with CGM technology

Access to downloadable data

Improved blood glucose

Improved quality of life

Fewer insulin injections

Disadvantages of insulin pump?

Bent/kinked cannulas

Insulin crystallization in the tubing

Accidental infusion set disconnection

Inflammation/hematoma at infusion site

Torn/kinked tubing

Adhesive issues

Pump failure (rare)

All of these issues increase your risk for a severe high blood sugar and DKA!

According to ADA 2026, what is the preferred insulin delivery method over MDI, CSII, and sensor-augmented pumps?

Automated insulin delivery (AID) systems for people with T1D, T2D, and other forms of insulin-deficient diabetes, including children and adolescents with T2D

How are insulin pumps typically covered by insurance, and what are the associated costs?

Traditional pumps → Usually billed through medical insurance; ~$6,000–8,000

Warranty → Typically 4–5 years before insurance replacement

Supplies → Ongoing infusion sets; ~$3,000–6,000 annually

Disposable patch pumps (Omnipod, Twiist) → Generally billed through pharmacy insurance