The CareLink system from Medtronic brings together data from your insulin pump and continuous glucose monitor into one unified view. You can access reports through the CareLink web portal or the companion mobile app. Each report organizes your data into several distinct sections: a summary dashboard, daily glucose traces, pattern detection views, and detailed insulin delivery logs. Learning how to navigate each section helps you focus on the information that matters most for your day-to-day management decisions.

When you open a report, the Dashboard gives you a high-level snapshot of your performance over the selected time window—usually 7, 14, or 30 days. Here you will find your Time in Range (TIR), average glucose, glucose variability metrics like standard deviation or coefficient of variation, and your total daily insulin dose (TDD). Below the dashboard, the Daily View displays a 24-hour glucose curve for each day, with insulin delivery events and manual entries for meals, exercise, or hypo treatments. The Patterns tab, when available, highlights recurring trends such as consistent highs or lows at specific times of day. The Insulin Logs section breaks down your basal rates, bolus doses, and correction amounts in a detailed table. Toggling between these views lets you move from the big picture to specific episodes that need attention.

The default report length matters. A 7-day report shows your most recent week and is useful for spotting acute issues like a post-illness adjustment or a recent change in therapy. A 14-day report smooths out day-to-day noise and reveals more reliable patterns. A 30-day report includes menstrual cycle effects in women and captures the impact of changes in routine. Start with 14 days for routine reviews and switch to 7 days when you are actively testing a new setting or recovering from an event.

Key Metrics: A Deeper Dive

Time in Range (TIR)

Time in Range measures the percentage of time your glucose stays between 70 mg/dL and 180 mg/dL. The international consensus recommends a TIR of at least 70% for most adults with type 1 or type 2 diabetes. Tighter targets apply during pregnancy, where a goal above 70% in a narrower range of 63 to 140 mg/dL is often used. A TIR below 50% indicates a need for significant therapy adjustment. Always review TIR together with time below range (TBR, below 70 mg/dL) and time above range (TAR, above 180 mg/dL). An ideal distribution shows TIR high, TBR under 4%, and TAR filling the remainder. The report color-codes these zones: red for dangerously low (below 54 mg/dL), orange for low (54 to 69 mg/dL), green for in range, yellow for high (181 to 250 mg/dL), and dark red for very high (above 250 mg/dL). Pay special attention to the red and orange percentages—even small amounts of time in these zones carry significant risk.

Average Glucose and Estimated A1C

The average glucose displayed on your report is the arithmetic mean of all CGM readings over the period. Clinicians use this value to estimate your A1C using a standard conversion: an average glucose of 154 mg/dL corresponds to an A1C of about 7.0%. However, average glucose can be misleading when your glucose variability is high. A person who spends half the day at 250 mg/dL and half at 70 mg/dL will have an average near 160 mg/dL, suggesting good control, but the actual experience includes dangerous highs and lows. Always pair average glucose with TIR and variability metrics to get a complete picture. If your estimated A1C and your lab-measured A1C differ by more than 0.5%, check for gaps in CGM wear or calibration issues that might distort the report.

Glucose Variability

Variability appears on the report as standard deviation (SD) or coefficient of variation (CV). CV is preferred because it adjusts for the average glucose level. A CV below 36% is considered stable; above 36% indicates high instability that increases your risk for both hypoglycemia and long-term complications. To calculate CV from the numbers on your report, divide the SD by the average glucose and multiply by 100. For example, an average of 150 mg/dL with an SD of 60 mg/dL gives a CV of 40%, which is high. High variability often stems from mismatched insulin timing, inconsistent meal composition, or exercise without appropriate insulin adjustment. Look at the daily traces on your report to see whether the variability comes from predictable patterns like post-meal spikes or from unpredictable swings that suggest a need for basal rate adjustments.

Insulin Usage: Basal versus Bolus

The report tracks how much insulin you deliver as basal (continuous 24-hour infusion) and as bolus (mealtime and correction doses). A healthy distribution typically falls between 40 to 60% basal and 60 to 40% bolus, but individual needs vary. Check for trends: if your total daily dose has changed by more than 20% compared to your previous report, investigate possible causes such as changes in insulin sensitivity, weight changes, or illness. Pay attention to your correction factor effectiveness. The report shows how often you need to deliver correction doses and whether those corrections bring your glucose back to target within two to three hours. Frequent corrections suggest that your insulin-to-carb ratios or basal rates need adjustment. Also review the number of missed meal boluses—a high count indicates opportunities to improve adherence with simple strategies like using the pump’s bolus calculator or setting reminders.

Interpreting Common Patterns

The Dawn Phenomenon

If your glucose rises steadily between 3:00 AM and 8:00 AM without a preceding low, you are experiencing the dawn phenomenon. On the daily graph, look for a smooth upward slope starting in the early morning hours. The CareLink pattern view can confirm whether this occurs on most days. The underlying cause is a natural rise in cortisol and growth hormone that signals your liver to release glucose. To address the dawn phenomenon, consider increasing your overnight basal rate starting around 2:00 or 3:00 AM, typically by 0.1 to 0.2 units per hour. You might also adjust your insulin-to-carb ratio for breakfast or change the composition of your evening meal—higher protein and fat at dinner can blunt the morning cortisol surge. If you use a hybrid closed-loop system, the algorithm may already adjust for the dawn phenomenon, but reviewing the report can tell you whether the automated adjustments are sufficient or whether manual override settings need refinement.

Postprandial Hyperglycemia

A glucose spike of more than 50 mg/dL within two hours after a meal, with values staying elevated for several hours, signals that your bolus timing or dose is off. Use the report to identify which meals cause the largest spikes. Compare the timing of your bolus with the CGM trace. A pre-bolus of 15 to 20 minutes before eating usually reduces the spike. If you are already pre-bolusing and still see spikes, consider increasing your insulin-to-carb ratio by 5 to 10% or splitting your bolus—giving part before the meal and the rest during or immediately after. The CareLink report also shows the effectiveness of your correction factor. If a high glucose reading does not come down as expected within three hours of a correction bolus, your correction factor may need to be more aggressive. Note that high-fat meals slow gastric emptying and can cause delayed spikes three to five hours after eating—these require a different strategy, such as an extended bolus or a dual-wave bolus.

Rebound Hypoglycemia and Hyperglycemia

A low glucose followed by a sharp rise above 200 mg/dL appears as a V-shaped or U-shaped pattern on the daily trace. This rebound effect, sometimes called the Somogyi effect, occurs when you overtreat a low with too many fast-acting carbohydrates. The report may flag this as a paired event. Distinguishing rebound from a true high is important because the treatment differs. If you treat a low with 15 grams of simple carbs and recheck in 15 minutes, the rebound is less likely. A frequent rebound pattern suggests your nighttime basal rate is too high, causing the initial low. Review your overnight basal profile and reduce the rate during the hours when lows most often occur. If you see the rebound pattern during the day, examine your correction dose habits—are you giving too much insulin when you see a high after a low? Let the low fully resolve before correcting a subsequent high.

Insulin Stacking and Late Corrections

CareLink records every insulin dose with a timestamp. Look for patterns where you deliver multiple correction boluses within a three-hour window. This behavior, called insulin stacking, leads to delayed hypoglycemia because the insulin from the first correction is still active when the second dose peaks. The report may show a period of stable or declining glucose followed by a sudden drop two to four hours after the stacked corrections. To prevent stacking, set your active insulin time (insulin on board duration) to at least four hours in your pump settings. Always check your glucose before repeating a correction, and rely on the pump’s bolus calculator, which accounts for insulin on board. If you find yourself correcting frequently, the underlying issue is likely an incorrect basal rate or insulin-to-carb ratio rather than a need for more correction doses.

Exercise affects glucose in two phases. During activity, glucose often drops due to increased insulin sensitivity and muscle glucose uptake. After exercise, especially intense or prolonged sessions, glucose can rise due to counter-regulatory hormone release. On your CareLink report, look for lows that consistently occur one to three hours after exercise sessions. Tag your exercise events in the report so you can review them separately. If you see post-exercise highs, your temporary basal reduction during activity may have been too aggressive, or you may need a small correction bolus after finishing. For aerobic exercise lasting more than 30 minutes, a common strategy is to reduce basal rate by 50 to 80% starting one hour before exercise and continuing through the activity. For anaerobic exercise like weightlifting, a temporary basal increase of 20 to 50% during and after the session may help prevent the rebound high.

Using the Report to Fine-Tune Your Therapy

Step 1: Establish Your Baseline

Open a 14-day or 30-day report and write down your current numbers: TIR, average glucose, CV or SD, TDD, and the percentage of time spent below 70 mg/dL and above 180 mg/dL. Note how many times you experienced a low below 54 mg/dL. This baseline gives you a starting point for measuring progress. Share these numbers with your endocrinologist or diabetes educator and discuss what targets make sense for your specific situation—goals for a person with hypoglycemia unawareness differ from those for someone with very stable control.

Step 2: Identify the Most Frequent Issue

Examine the pattern view and the daily traces to find the problem that occurs most often. If 70% of your lows happen between 10:00 PM and 2:00 AM, focus there first. If your highest TAR occurs between 11:00 AM and 2:00 PM, the issue is likely lunchtime bolusing. Resist the urge to fix everything at once. Choose the pattern that poses the greatest safety risk—typically, frequent or severe lows take priority over high glucose values. One pattern at a time is manageable; attempting multiple changes simultaneously makes it impossible to know which adjustment worked.

Step 3: Make One Change and Wait

Adjust only one variable per week. This could be a basal rate, an insulin-to-carb ratio, a correction factor, or a change in bolus timing. Record the change in the report notes section or in a separate log. After seven days, generate a new report and compare it to your baseline. For example, if you increase your overnight basal rate by 0.1 units per hour to address the dawn phenomenon, check whether the morning rise has diminished. If the pattern improved, keep the change. If not, try a different adjustment, such as altering the timing of the rate increase. Do not make a second change until you have evaluated the first one over a full week of data.

Step 4: Document and Communicate

Use the report’s comment or note feature to record changes you make, along with contextual factors like illness, stress, menstrual cycle phase, or changes in physical activity. These notes become invaluable when you review trends over longer periods. Share your annotated report with your healthcare team. Many clinics accept CareLink-generated PDFs for remote consultations. When you present the report to your clinician, point out the specific pattern you are working on and the change you made. This focused approach makes the visit more productive and leads to faster therapy optimization.

Advanced Features: Overlaying Data and Trend Arrows

CareLink allows you to overlay glucose data from multiple days. This feature reveals the typical shape of your glucose curve. If the overlaid lines spread widely during the afternoon, you have high day-to-day variability that needs investigation. If the lines cluster tightly but sit above target, you need a consistent adjustment to your basal or bolus settings. You can also overlay insulin delivery data to correlate lows or highs with the amount of insulin delivered at specific times. For instance, if you see a cluster of lows at 3:00 PM every day, check whether your lunch bolus is consistently too large or whether your afternoon basal rate is too high.

Trend arrows from your CGM appear in the mobile app and are preserved in the report data. These arrows indicate the direction and speed of glucose change. A single arrow pointing up means glucose is rising 1 to 2 mg/dL per minute. A double arrow up means a rise of 2 mg/dL per minute or more. These arrows are actionable in real time: a 45-degree up arrow suggests giving a correction before the glucose reaches a high level. When you review the report later, the arrow data help you understand whether your real-time decisions were appropriate. If you see a pattern where you ignored a rapid rise and ended up high for several hours, you can plan to act more quickly next time.

  • Focusing only on average glucose – Average glucose hides dangerous lows. Always check TIR and time below range first. A good average with high variability is not good control.
  • Ignoring sensor wear issues – If your CGM data gaps exceed 10% of the total time, the report becomes unreliable. Check sensor insertion sites and follow calibration guidelines. Replace sensors that fail frequently.
  • Misunderstanding time in range – TIR is not just about being inside the 70 to 180 mg/dL window. The distribution matters. A person with 70% TIR but 5% of time below 54 mg/dL needs different intervention than someone with 70% TIR and no lows. Examine the color-coded breakdown.
  • Overcorrecting based on one day – A single bad day does not constitute a trend. Always use at least seven days of data before making therapy changes. One high day might reflect a site issue, a missed dose, or an unannounced meal.
  • Not adjusting for exercise or illness – The report includes tags for exercise and sick days. Review these days separately because insulin requirements shift dramatically during activity and illness. Your standard basal rates may be too high when you are active and too low when you are sick.
  • Ignoring time-of-day patterns – A high overall TIR with frequent nocturnal lows still places you at risk for severe hypoglycemia. Segment your analysis into four blocks: morning (6 AM to noon), afternoon (noon to 6 PM), evening (6 PM to midnight), and overnight (midnight to 6 AM). Address each block separately.
  • Failing to update pump settings after analysis – Interpreting the report without making changes is wasted effort. Have a system for implementing adjustments directly in your pump or through your clinician’s portal. Set a reminder to review the next report after one week.

Where to Learn More

For official guidance on interpreting CareLink reports, visit Medtronic’s CareLink support page, which offers video tutorials and downloadable reference guides. The American Diabetes Association publishes updated standards of care that include target metrics for time in range and glucose variability—see the ADA Standards of Medical Care in Diabetes. For a deeper look at the research behind time-in-range targets, the clinical consensus paper in Diabetes Care provides a thorough analysis at doi.org/10.2337/dc19-0028. The JDRF Time in Range initiative offers practical tips for improving your TIR through daily decisions about food, activity, and insulin timing.

Building Long-Term Habits with Your Reports

Interpreting CareLink reports becomes more intuitive the more you do it. Make it a weekly habit to open a 14-day report and scan the dashboard for changes. Set a recurring calendar reminder for Sunday evening or another consistent time. After three months of regular review, most people can spot trouble patterns within seconds. The goal is not to obsess over each number but to build confidence in your ability to identify what needs attention.

When you see a positive trend, acknowledge it. A rising TIR or a decrease in nocturnal lows is real progress. When you see a problem, resist the urge to blame yourself. Instead, treat it as a signal that a setting needs adjustment or that a new variable has entered your life. Document what you tried and what happened so you build a personal knowledge base over time. You will learn how specific foods, stress levels, types of exercise, and even sleep quality affect your glucose. Your CareLink report becomes a roadmap to better health rather than a source of frustration.

Remember that the report is a tool, not a judgment. Perfect control every day is not realistic. The goal is to steadily increase your time in range while minimizing dangerous lows. Each report gives you the information you need to make the next small improvement. The more you practice using your CareLink data, the more intuitive and proactive your diabetes management becomes.