Interpreting Trend Arrows

What Trend Arrows Mean

Trend arrows on Continuous Glucose Monitors visualize the Rate of Change (ROC) of interstitial glucose—representing the first derivative of glucose concentration.

Predicting the Future

These arrows allow users to predict future glucose levels (typically 30 minutes out) and adjust treatment proactively.

Arrow Meanings

| Arrow | Rate of Change | Prediction | |-------|---------------|------------| | → (Stable) | Less than 1 mg/dL/min | Glucose holding steady | | ↗ or ↘ (Moderate) | 1–2 mg/dL/min | ~30-60 mg/dL change in 30 min | | ↑ or ↓ (Rapid) | 2–3 mg/dL/min | ~60-90 mg/dL change in 30 min | | ↑↑ or ↓↓ (Very Rapid)* | >3 mg/dL/min | >90 mg/dL change in 30 min |

*Very rapid arrows are Dexcom-specific

Clinical Application

Trend Arrow Adjustment

Insulin dosages can be increased or decreased to account for the velocity of glucose flux:

• Rising arrows: Consider additional correction
• Falling arrows: Reduce dose or add carbs

Important Limitations

• Physiological lag: Remember the 5-15 minute delay between blood and interstitial fluid
• Compression artifacts: Pressure on sensor can cause false falling arrows
• Meal timing: Post-meal arrows may not predict long-term trends