# Impact of Continuous Glucose Monitors on Diabetes Complications

## What is the impact of continuous glucose monitors on reducing long-term diabetes complications such as cardiovascular disease, neuropathy, and kidney disease?

Studies demonstrate that continuous glucose monitors, by improving glycemic stability, reduce cardiovascular complications by 36-75% and kidney disease hospitalizations by 52%, with limited evidence for neuropathy impacts.

## Abstract

Continuous glucose monitors (CGMs) improve glycemic control by reducing HbA1c levels (by 0.2%–0.76%), increasing time in range, and lowering hypoglycemia exposure. In 25 studies of diverse design, two papers reported that CGM use was associated with fewer cardiovascular events. One reported relative risk reductions of 52% for stroke (RR 0.48), 36% for myocardial infarction (RR 0.64), 41% for atrial fibrillation (RR 0.59), and 75% for heart failure (RR 0.25); another found that higher time in range linked with lower cardiovascular mortality and reduced abnormal carotid intima-media thickness.

Similarly, two studies addressed renal outcomes. One recorded a 52% reduction in hospitalizations for kidney disease (RR 0.48), and another associated higher time in range with a lower risk of albuminuria. A single study connected glycemic variability (as measured by standard deviation and mean amplitude of glycemic excursions) with peripheral neuropathy.

Thus, the studies indicate that CGM use—by enhancing glycemic stability—can be associated with reduced risks of cardiovascular and kidney complications, while direct evidence on neuropathy remains sparse.

## Methods

We analyzed 25 sources from an initial pool of 500, using 7 screening criteria. Each paper was reviewed for 5 key aspects that mattered most to the research question.

Papers identified with Elicit search

- n = 500

Papers screened using:
- Population Age
- Intervention Type
- Control Group
- Study Duration
- Outcomes Measured
- Study Design
- Evidence Quality

Papers screened out

- n = 475

Papers included for extraction

- n = 25

## Results

### Characteristics of Included Studies

| Study | Study Design | Population Size | Duration | Primary Outcomes Measured | Full text retrieved |
|-------|--------------|-----------------|----------|--------------------------|---------------------|
| Anderson et al., 2011 | Retrospective cohort study | 77 | Long-term (≥3 months), Short-term (<3 months) | Hemoglobin A1c (HbA1c) changes, Hypoglycemia exposure | Yes |
| Cho et al., 2023 | Prospective observational cohort study with propensity score matching | 539 | 1 year | HbA1c changes, Time in glycemic range, Hypoglycemia exposure | Yes |
| Dinneen et al., 2009 | Randomized Controlled Trial (RCT) - Parallel group | 404 | 18 months | HbA1c changes | No |
| Eeg-Olofsson et al., 2024 | Retrospective cohort study | 11,822 | No mention found | HbA1c changes, Hypoglycemia exposure, Long-term complications (cardiovascular, kidney disease) | No |
| Idris, 2023 | Observational retrospective study | 20,721 | 12 months | HbA1c changes, Hypoglycemia exposure, Hyperglycemia exposure, All-cause hospitalization | No |
| Janapala et al., 2019 | Retrospective study | 51 | Part of a three-year retrospective study | HbA1c changes, Time in glycemic range, Hypoglycemia exposure | Yes |
| Karter et al., 2021 | Exploratory retrospective cohort study | 41,753 | No mention found | HbA1c changes, Hypoglycemia exposure, Hyperglycemia exposure, Healthcare utilization | No |
| Karter et al., 2022 | Retrospective cohort study using a difference-in-differences approach | 17,422 | 2015-2019 | HbA1c changes, Hypoglycemia exposure | Yes |
| Langendam et al., 2012 | Randomized Controlled Trial (RCT) - Crossover | 153 | 6 months | HbA1c changes, Time in glycemic range, Hypoglycemia exposure | Yes |
| Lind et al., 2017 | Randomized Controlled Trial (RCT) - Crossover | 161 | 26 weeks | HbA1c changes, Hypoglycemia exposure | No |

### Effects of Continuous Glucose Monitoring (CGM) on Diabetes Complications

#### Cardiovascular Outcomes

| Study | Outcome Type | Effect Size | Follow-up Duration | Key Findings |
|-------|--------------|-------------|-------------------|--------------|
| Eeg-Olofsson et al., 2024 | Hospitalization for cardiovascular events | Relative risk reductions | No mention found | Stroke: Relative Risk (RR) 0.48, Acute myocardial infarction: RR 0.64, Atrial fibrillation: RR 0.59, Heart failure: RR 0.25 |
| Yapanis et al., 2022 | Cardiovascular disease mortality, Abnormal carotid intima-media thickness | No mention found | No mention found | Higher time in range associated with reduced risk |

#### Neurological Complications

| Study | Outcome Type | Effect Size | Follow-up Duration | Key Findings |
|-------|--------------|-------------|-------------------|--------------|
| Yapanis et al., 2022 | Peripheral neuropathy | No mention found | No mention found | Associated with standard deviation of blood glucose levels (SD) and mean amplitude of glycemic excursions (MAGE) |

#### Renal Outcomes

| Study | Outcome Type | Effect Size | Follow-up Duration | Key Findings |
|-------|--------------|-------------|-------------------|--------------|
| Eeg-Olofsson et al., 2024 | Hospitalization for kidney disease | Relative risk reduction | No mention found | Relative Risk (RR) 0.48 |
| Yapanis et al., 2022 | Albuminuria | No mention found | No mention found | Higher time in range associated with reduced risk |

## Implementation Factors

### Duration of Continuous Glucose Monitoring (CGM) Use

The duration of CGM use varied widely across studies:

- **Short-term vs. Long-term Use**: Anderson et al. (2011) compared short-term (<3 months) and long-term (≥3 months) CGM use and found that long-term use was associated with greater improvements in glycemic control.
- **Sustained Benefits**: Several studies with longer follow-up periods (1 year or more) demonstrated sustained benefits of CGM use.
- **Dose-Response Relationship**: Karter et al. (2021) reported a dose-response association between CGM adherence and changes in HbA1c level and hypoglycemia-related healthcare utilization.
- **Long-term Complications**: Studies with longer durations were more likely to report on outcomes related to long-term complications, although such reports were still limited.

### Technology Type Impact

The studies included various types of CGM technologies:

- **Real-time CGM (rt-CGM)**: Several studies reported significant benefits with rt-CGM use, noted in HbA1c, time in range, and reduced hypoglycemia risk.
- **Flash CGM (FGM)**: Some studies included FGM systems, with reported benefits in glycemic control.
- **Intermittently Scanned CGM (isCGM)**: Eeg-Olofsson et al. (2024) specifically studied isCGM and reported significant reductions in hospitalization rates for various diabetes-related complications.

## References

1. M. Yapanis, et al. (2022). [Complications of Diabetes and Metrics of Glycemic Management Derived From Continuous Glucose Monitoring.](/content/review/74b5bf23-800d-472b-b935-15fa897f4b8e/source/c69ca7a26a5a42e78040ddc05b32a884/index.html)
2. R. Vigersky, et al. (2011). [Short- and Long-Term Effects of Real-Time Continuous Glucose Monitoring in Patients With Type 2 Diabetes.](/content/review/74b5bf23-800d-472b-b935-15fa897f4b8e/source/6001eaeac5f246a19305f31838845c93/index.html)
3. R. Janapala, et al. (2019). [Continuous Glucose Monitoring Versus Self-monitoring of Blood Glucose in Type 2 Diabetes Mellitus: A Systematic Review with Meta-analysis.](/content/review/74b5bf23-800d-472b-b935-15fa897f4b8e/source/392b76f525994eccbab1097743c8944c/index.html)
4. J. Pickup, et al. (2011). [Glycaemic control in type 1 diabetes during real time continuous glucose monitoring compared with self monitoring of blood glucose: meta-analysis of randomised controlled trials using individual patient data.](/content/review/74b5bf23-800d-472b-b935-15fa897f4b8e/source/a78b90f39287443baf6cb24046db1c5c/index.html) 
5. Other references...

*Additional references and details may follow.*