What are the recommended glucose target ranges for an adult with type 2 diabetes using continuous glucose monitoring (CGM)?

Target Glucose Ranges for Type 2 Diabetes with CGM

For adults with type 2 diabetes using continuous glucose monitoring, maintain glucose between 70-180 mg/dL for more than 70% of the time, with less than 4% of time below 70 mg/dL and less than 25% of time above 180 mg/dL. 1, 2

Primary Target Metrics

Your CGM should show the following ranges over at least 14 consecutive days with ≥70% active sensor time 1, 2:

Time in Range (TIR): 70-180 mg/dL

• Target: >70% of readings (approximately 17 hours per day) 3, 1, 2
• Each 5% increase in TIR provides measurable reductions in microvascular complications like retinopathy and nephropathy 2
• This is the single most important metric correlating with long-term diabetes complications 3

Time Below Range (Hypoglycemia Prevention)

• Level 1 (54-69 mg/dL): <4% of time (less than 1 hour per day) 1, 2
• Level 2 (<54 mg/dL): <1% of time (less than 15 minutes per day) 1, 2
• This is your safety-first priority—hypoglycemia prevention takes precedence over achieving tight glucose control 2

Time Above Range (Hyperglycemia Limits)

• Level 1 (181-250 mg/dL): <25% of time (less than 6 hours per day) 1, 2
• Level 2 (>250 mg/dL): <5% of time (less than 1 hour 12 minutes per day) 2
• Minimizing time above 250 mg/dL reduces risk of acute complications and long-term cardiovascular disease 1

Glucose Variability

• Coefficient of variation (CV): ≤36% 3, 1, 2
• If you take insulin or sulfonylureas, aim for CV <33% for additional hypoglycemia protection 3, 1
• Lower variability means more stable, predictable glucose patterns 1

Modified Targets for Special Circumstances

Older Adults or High-Risk Patients

If you have a history of severe hypoglycemia, hypoglycemia unawareness, limited life expectancy (<10 years), advanced complications, or significant frailty 2, 4:

• TIR: >50% (at least 12 hours per day in 70-180 mg/dL) 1, 2
• Combined TBR: <1% (less than 15 minutes per day below 70 mg/dL) 1, 2
• TAR >250 mg/dL: <10% (less than 2 hours 24 minutes per day) 1
• These relaxed targets prioritize safety over tight control 2, 4

Advanced Chronic Kidney Disease

If you have advanced CKD or are on hemodialysis 2:

• TIR: >50% (more conservative due to impaired kidney gluconeogenesis and decreased insulin clearance) 2
• TBR: <1% (stricter hypoglycemia prevention given increased risk) 2
• Use Glucose Management Indicator (GMI) instead of HbA1c when they don't match, as HbA1c becomes unreliable in kidney disease 2

Practical Implementation Algorithm

Follow this sequence when reviewing your CGM data 2:

1. First: Verify hypoglycemia safety—Confirm TBR <54 mg/dL is <1% and TBR 54-69 mg/dL is <4% 2

   • If TBR exceeds these targets, do not intensify therapy; instead reduce insulin doses or adjust timing 4

2. Second: Check efficacy—Verify TIR 70-180 mg/dL is >70% (or >50% if high-risk) 2

   • If TIR is below target and TBR is acceptable, consider intensifying glucose-lowering therapy 4

3. Third: Assess variability—Confirm CV is ≤36% 2

   • High variability suggests erratic eating patterns, medication timing issues, or need for automated insulin delivery 1

4. Fourth: Address hyperglycemia—Check TAR >250 mg/dL is <5% and TAR 181-250 mg/dL is <25% 2

   • If TAR is the predominant issue, intensify therapy by adjusting insulin, adding/optimizing medications, or considering GLP-1 receptor agonists or SGLT2 inhibitors 4, 5

Data Collection Requirements

Before making any treatment decisions based on CGM 1, 2:

• Minimum 14 consecutive days of sensor wear 1, 2
• At least 70% active sensor time (approximately 10 days of usable data) 1, 2
• Review the complete Ambulatory Glucose Profile (AGP) report showing all 10 standardized metrics 1, 4
• For assessing hypoglycemia patterns specifically, collect 28-35 days of data 2

Critical Pitfalls to Avoid

Don't focus only on average glucose or GMI—you can have a normal average but still experience dangerous highs and lows that the average conceals 1. A patient with 50% time at 250 mg/dL and 50% time at 70 mg/dL would show an acceptable average of 160 mg/dL but terrible glucose control 1.

Don't make medication changes without reviewing the complete AGP—the visual display reveals patterns (dawn phenomenon, post-meal spikes, overnight lows) that raw percentages miss 4.

Don't assume low TBR percentages mean no hypoglycemia risk—even individuals with <4% TBR can experience substantial numbers of severe hypoglycemic events, so monitor frequency separately 2.

Don't use the same targets for everyone—older adults, those with kidney disease, and patients with hypoglycemia unawareness require more conservative goals to prevent dangerous lows 2, 4.

Corresponding HbA1c Target

The CGM-derived Glucose Management Indicator (GMI) should be <7% (approximately 53 mmol/mol), which corresponds to a mean glucose of approximately 154 mg/dL 3, 4. However, CGM metrics provide more actionable information than HbA1c alone because they reveal the timing and patterns of glucose excursions 6.