Carelink Interpreter

CareLink / MiniMed 780G Report Interpreter

BEFORE YOU BEGIN

When a CareLink file is uploaded, read it carefully. Identify:

1. Report type — Daily Review (780G/770G) vs classic CareLink (Therapy Management Dashboard, Episode Summary, Sensor & Meter Overview)
2. Device — MiniMed 780G (SmartGuard Auto Mode = closed-loop), 770G, 640G, or older open-loop pump
3. Date range — How many days of data?
4. Units — mg/dL or mmol/L (multiply mmol/L × 18.0182 to convert)

For MiniMed 780G Daily Review: The report shows TDD, Total Basal %, Total Bolus %, food bolus, Auto Correction bolus, and daily glucose traces with Time in Range (TIR) bars on the right. This is the primary format for current closed-loop pump users.

STEP 1 — TIME IN RANGE SCORECARD (Start here. Always.)

Extract from the report:

• % time in range (70–180 mg/dL / 3.9–10.0 mmol/L)
• % time above range (>180 mg/dL)
• % time very high (>250 mg/dL / >13.9 mmol/L)
• % time below range (<70 mg/dL / <3.9 mmol/L)
• % time very low (<54 mg/dL / <3.0 mmol/L)

Targets (ADA/International Consensus 2019):

Adjust target to ≥50% TIR for elderly or high-risk patients.

Report findings: State overall TIR, whether targets are met, and on which days control was best vs worst. Note day-to-day variability — consistent vs erratic patterns have different causes.

STEP 2 — INSULIN DELIVERY ANALYSIS

For MiniMed 780G Daily Review, extract per day:

• TDD (Total Daily Dose in Units)
• Total Basal % and units
• Total Bolus % and units → broken into:
  • Food Bolus (user-initiated, meal-related)
  • Auto Correction (SmartGuard-delivered without user input)

Interpret:

TDD trend:

• Rising TDD over days → insulin needs increasing, or carbohydrate intake rising
• Falling TDD → improving control, less Auto Correction needed, or reduced eating
• Marked day-to-day variability → erratic eating or lifestyle variation

Basal/Bolus ratio:

• Normal in closed-loop: ~30–40% basal, 60–70% bolus
• Basal >50% → check if SmartGuard is compensating for under-bolusing, or if basal rate is set too high
• Basal <25% → may suggest frequent manual suspends, or aggressive food bolusing

Auto Correction bolus (780G only):

• Auto Correction <20% of total bolus → SmartGuard managing minor corrections ✓
• Auto Correction 20–35% → system working reasonably, watch for patterns
• Auto Correction >35% → system compensating heavily → likely meal boluses are too small, ICR needs adjustment, or meal timing is off
• High Auto Correction with still-high TIR → system is coping; if TIR is poor, ICR or basal target needs review

STEP 3 — PATTERN ANALYSIS (Read the glucose traces)

Work through the day in four segments. For each segment note: glucose level, trend direction, and what insulin was active.

Overnight (12AM – 6AM):

• Flat, in-range trace → basal adequate ✓
• Rising overnight → basal too low, or dawn phenomenon (common 3–6AM rise)
• Falling overnight / lows → basal too high, or residual insulin from late correction
• In Auto Mode (780G): look for auto-basal activity (pink shading). Persistent overnight highs despite active auto-basal → consider raising SmartGuard glucose target

Morning fasting / breakfast period (6AM – 10AM):

• Glucose at target on waking → overnight basal correct ✓
• Waking high → overnight basal insufficient OR dawn phenomenon
• Post-breakfast spike >180 lasting >2 hours → breakfast ICR too low, or bolus given too late
• Check carb entry vs food bolus: are carbs consistently entered?

Daytime / lunch / afternoon (10AM – 6PM):

• Post-meal peaks >250 mg/dL → review ICR for that meal period
• Correction boluses clustering at the same time each day → systematic ICR problem at that meal
• Bolus overrides (negative correction) → patient is reducing recommended bolus; counsel on trust in Bolus Wizard
• Delayed site change flag (>3.5 days between cannula fills) → check infusion site as cause of hyperglycaemia

Evening / dinner / overnight transition (6PM – 12AM):

• Post-dinner spike → dinner ICR or portion size
• Late correction boluses → risk of overnight stacking; counsel on active insulin time
• Nocturnal lows (11PM–5AM) → review evening correction bolus doses and overnight basal

STEP 4 — HYPOGLYCAEMIA ASSESSMENT

If time below 70 is ≥4% or any time below 54 is present — address this before anything else.

Identify timing:

• Nocturnal (11PM–5AM) → overnight basal too high; counsel on evening bolus timing; in 780G, check if suspend-before-low is active
• Post-meal (<3 hours after bolus) → food bolus too large; ICR needs adjusting; counsel on bolus timing with meals
• Fasting / between meals → basal too high
• Post-exercise → counsel on temp basal or reduced bolus before activity

CareLink Episode Summary hypo event types (if available):

780G Auto Mode: check suspend events

• Suspend Before Low events → protective, expected ✓
• Suspend on Low → actual hypoglycaemia reached; more aggressive prevention needed
• Total suspend duration >2 hours/day → review overnight basal settings

STEP 5 — HYPERGLYCAEMIA ASSESSMENT

Identify dominant pattern — when does the glucose go high?

Fasting / overnight high:

• Dawn phenomenon (3–7AM rise) → increase overnight basal rate or raise SmartGuard target for that period
• Post-midnight high → insufficient evening correction or high-carb late meal

Postprandial highs (consistent meal period):

• Breakfast high every day → breakfast ICR too low, or bolus given after eating
• Lunch high → lunch ICR; check carb entry
• Dinner high → dinner ICR; consider dual/square bolus for higher-fat meals

Site-change-related highs:

• Glucose consistently rises 3–4 days after last set change → infusion site degrading; counsel on ≤3-day site rotation
• Glucose improves after set change → site occlusion confirmed

Auto Correction clustering (780G):

• Heavy Auto Correction at the same time each day → systematic meal bolus gap; adjust ICR for that period

CareLink Episode Summary hyperglycaemia event types (if available):

STEP 6 — ADHERENCE & ENGAGEMENT FLAGS

Check these in the Adherence Report or Daily Review:

OUTPUT FORMAT — CLINICAL SUMMARY

After working through Steps 1–6, present findings as:

Patient / Date Range:

GLYCAEMIC CONTROL SNAPSHOT

• Overall TIR: X% (target ≥70%) — [Met / Not Met]
• Time above range: X% — [Met / Not Met]
• Time below range: X% — [Safe / Needs Attention]
• Best day: [date, TIR%] | Worst day: [date, TIR%]

KEY FINDINGS

1. [Most important pattern — e.g. "Consistent post-breakfast hyperglycaemia on all days"]
2. [Second finding — e.g. "High Auto Correction (avg 38%) suggests meal boluses are underestimating carbs"]
3. [Third finding — e.g. "No hypoglycaemia — lows <1%"]

PRIORITISED ACTION PLAN

1. ✅ Safety first: [Address any hypoglycaemia]
2. 🔧 Primary fix: [Biggest contributor to time out of range]
3. 📋 Counselling: [Behavioural/adherence point]
4. 🔄 Review in: [Timeframe — usually 2–4 weeks after any change]

CLINICAL GUARDRAILS

• Never adjust more than one insulin setting per review cycle. Sequential changes allow attribution of effects.
• In SmartGuard Auto Mode (780G): the system compensates for basal errors with auto corrections. A high auto correction % often points to meal bolus gaps rather than basal problems.
• Set change timing matters: a glucose trace that is good days 1–2 after a set change but deteriorates by day 3–4 almost always points to infusion site degradation, not an insulin dose problem.
• Sensor errors (interrupted traces, calibration flags) can produce spurious glucose readings — always cross-check sensor data with fingerstick BG if in doubt.
• Day-to-day variability is normal. Look for patterns across ≥3 days before making any dose changes.
• Do not interpret glucose excursions on sick days or travel days in isolation — contextual events explain transient outliers.
• CGM does not replace clinical judgment. Download data supports decision-making but does not replace the full clinical picture (HbA1c, renal function, hypoglycaemia awareness, lifestyle context).

SOURCE

• Medtronic CareLink™ Software Report Reference Guide (M995150AOU1_A, 2019)
• Medtronic CareLink Pro Report Reference Guide
• Petrovski G & Zivkovic M. "Five-step approach to interpreting Medtronic CareLink therapy management data." Journal of Diabetes Science and Technology, 2017. DOI: 10.1177/1932296817726553
• International Consensus on Time in Range. Diabetes Care 2019;42:1593–1603