A1c has long been the gold standard for evaluating diabetes control. But it’s only part of the picture. Thanks to continuous glucose monitoring (CGM) and expanded data tracking, new metrics now offer a more detailed and personalized look at how blood sugar behaves day to day.

Here’s why glucose trends, GMI, Time in Range, and variability often tell a deeper story than A1c alone.

🩸 What A1c Measures

A1c reflects the average blood sugar over the past 2 to 3 months by measuring how much glucose is attached to hemoglobin in the blood.

• A result of 5.7% to 6.4% is considered prediabetes

• 6.5% or higher confirms a diabetes diagnosis

• A common treatment goal is an A1c below 7.0%, depending on individual factors

While A1c is useful, it comes with limitations.

⚠️ Why A1c Has Blind Spots

A1c is an average, which means it doesn't reflect blood sugar highs and lows. For example:

• Someone with frequent highs and lows may still average out to a "normal" A1c

• Anemia or certain blood disorders can falsely lower or raise A1c

• It doesn’t show what time of day glucose is elevated, which limits treatment precision

This is where CGM-derived data adds powerful context.

📊 What GMI and Time in Range Show

GMI (Glucose Management Indicator) estimates your A1c using real-time glucose data from a CGM. It reflects how you're doing day to day, rather than averaging months of ups and downs.

Time in Range shows the percentage of time your glucose is within your target range, usually 70 to 180 mg/dL. It helps answer questions A1c cannot:

• Are your readings mostly stable with occasional spikes?

• Do your glucose levels rise overnight or after meals?

• Are lows happening more often than you realize?

Most people with diabetes benefit from a Time in Range goal of at least 80 percent.

📈 What Glucose Variability Tells You

Glucose variability refers to how much your blood sugar swings throughout the day. Even if your average looks fine, large swings between highs and lows can lead to:

• Fatigue, mood changes, and brain fog

• Increased cardiovascular risk

• Reduced quality of life and energy

Lowering glucose variability helps stabilize how you feel and improves long-term outcomes. It’s especially important for those who experience crashes or wide swings around meals, activity, or medication timing.

🧠 Why These Metrics Matter Together

A1c gives a general picture. But GMI, Time in Range, and variability fill in the details of how your body handles glucose in real life.

When used together, these metrics can:

• Identify hidden patterns

• Improve your response to medications or lifestyle changes

• Catch early warning signs of complications

• Help personalize your diabetes plan with greater accuracy

📋 Ready for a Full Glucose Review?

📅 Book a visit to review your A1c, glucose patterns, time in range, GMI, and variability together.

Whether you're using a CGM or traditional monitoring, or want to get started on monitoring, getting clarity on these numbers can help you feel better, reduce risk, and take the guesswork out of your care.