The Two Main Ways to Monitor Blood Sugar
For people managing diabetes, keeping blood sugar in check is a daily priority. Two types of monitoring tools dominate the market: traditional blood glucose meters (BGMs) and continuous glucose monitors (CGMs). Both measure blood sugar, but they work very differently — and choosing between them depends on your lifestyle, health goals, and insurance coverage.
What Is a Blood Glucose Meter (BGM)?
A blood glucose meter is the traditional tool for checking blood sugar. It requires a small finger-prick blood sample, which is applied to a test strip that the meter then reads. Results appear within seconds and give you a snapshot of your glucose level at that exact moment.
Pros of BGMs:
- Lower upfront and ongoing costs
- Widely available at pharmacies without a prescription
- Simple and straightforward to use
- No sensor to wear on your body
- Many models are compact and highly portable
Cons of BGMs:
- Only captures a single point-in-time reading
- Requires multiple daily finger pricks to track trends
- Misses overnight fluctuations or post-meal spikes unless you test frequently
- Finger pricks can be uncomfortable over time
What Is a Continuous Glucose Monitor (CGM)?
A CGM uses a small sensor worn on the skin — typically the upper arm or abdomen — to measure glucose levels in the fluid just below the skin surface. It sends readings to a receiver, smartwatch, or smartphone app every few minutes, around the clock.
Pros of CGMs:
- Continuous data — you can see trends, not just single snapshots
- Alerts for high or low blood sugar (including at night)
- No finger pricks required for most models
- Helps identify patterns triggered by food, exercise, or stress
- Some models are approved for insulin dosing decisions
Cons of CGMs:
- Significantly higher cost — sensors must be replaced every 10–14 days
- Measures interstitial fluid, not blood directly, so there is a slight lag
- Requires skin adhesive tolerance and regular sensor changes
- May need calibration with a finger prick on some models
- Prescription usually required
Side-by-Side Comparison
| Feature | Blood Glucose Meter | CGM |
|---|---|---|
| Measurement frequency | On demand | Every 1–5 minutes |
| Finger pricks needed | Yes, every reading | Rarely or never |
| Real-time trend data | No | Yes |
| Alerts & alarms | No | Yes |
| Typical ongoing cost | Lower | Higher |
| Prescription required | Usually not | Usually yes |
| Best for | Type 2, occasional checks | Type 1, intensive management |
Who Should Use a CGM?
CGMs are particularly valuable for people with Type 1 diabetes, those on multiple daily insulin injections, or anyone who experiences hypoglycemia unawareness (not feeling warning signs of low blood sugar). The real-time trend data helps users and their doctors fine-tune insulin doses and lifestyle habits with much greater precision.
Who Is a Blood Glucose Meter Best For?
BGMs remain an excellent and cost-effective choice for many people with Type 2 diabetes who manage their condition through diet, exercise, or oral medications. They're also a reliable backup for CGM users when sensor accuracy needs to be confirmed.
Insurance and Coverage Considerations
Coverage varies significantly by insurer and plan. Medicare, for instance, covers CGMs for certain qualifying patients. Always check with your insurance provider and doctor before deciding — the out-of-pocket difference between BGMs and CGMs can be substantial without coverage.
The Bottom Line
Neither tool is universally better — the right choice depends on your type of diabetes, how closely you need to manage your levels, your budget, and your comfort with wearable technology. Many people use both: a CGM for daily management and a BGM as a backup. Talk to your endocrinologist or diabetes care team to find the combination that fits your needs best.