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.

Data extraction

We asked a large language model to extract each data column below from each paper. We gave the model the extraction instructions shown below for each column.

Study Design:

Identify the specific type of study design used:

• Randomized controlled trial (RCT)
• Systematic review
• Meta-analysis
• Other

Participant Characteristics:

Extract the following participant details:

• Diabetes type (Type 1 or Type 2)
• Age range or mean age
• Total number of participants
• Gender distribution
• Baseline HbA1c levels
• Duration of diabetes

Continuous Glucose Monitor (CGM) Intervention Details:

Specify:

• Type of CGM used (real-time, flash, intermittently scanned)
• Duration of CGM intervention
• Frequency of CGM usage per week
• Any specific instructions for CGM use

Primary Outcomes Measured:

List all primary outcomes, specifically focusing on:

• HbA1c changes
• Time in glycemic range
• Hypoglycemia exposure
• Long-term diabetes complications (cardiovascular disease, neuropathy, kidney disease)

Study Limitations:

Extract:

• Acknowledged study limitations
• Sample size constraints
• Potential biases
• Generalizability concerns

Results

Characteristics of Included Studies

Among the included studies, we found a mix of study designs and characteristics:

• Study Design:
  • Retrospective cohort studies appeared to be the most common (7 studies)
  • Meta-analyses and systematic reviews (5 studies)
  • Randomized Controlled Trials (RCTs) (7 studies total, with 4 parallel and 3 crossover designs)
• Population Size:
  • 11 studies had between 100-1000 participants
  • 7 large-scale studies with over 10,000 participants
• Duration: Study durations varied widely in the information available to us:
  • 6 studies lasting 1 year
  • 5 studies lasting more than 1 year
  • 3 studies lasting 6 months
• Primary Outcomes:
  • HbA1c changes and hypoglycemia exposure were the most commonly measured outcomes
  • Time in glycemic range was reported in 8 studies

Effects of Continuous Glucose Monitoring (CGM) on Diabetes Complications

Cardiovascular Outcomes

Neurological Complications

Renal Outcomes

Relationship Between Glycemic Variability and Complications

While most studies did not directly assess long-term diabetes complications, many focused on glycemic control measures that are indirectly related to long-term outcomes:

• HbA1c Reduction:
  • Most studies reported significant reductions in HbA1c levels with CGM use
• Time in Range:
  • Several studies reported improvements in time in range with CGM use
• Hypoglycemia Reduction:
  • Many studies reported reductions in hypoglycemia risk or exposure with CGM use
• Glycemic Variability:
  • Linked with complications

Implementation Factors

Duration of Continuous Glucose Monitoring (CGM) Use

The duration of CGM use varied widely across studies. Long-term users saw greater improvements in glycemic control.

Technology Type Impact

The studies included various types of CGM technologies with reported benefits in glycemic control.

References

• (2022). Complications of Diabetes and Metrics of Glycemic Management. Journal of Clinical Endocrinology and Metabolism
• (2011). Short- and Long-Term Effects of Real-Time Continuous Glucose Monitoring in Patients With Type 2 Diabetes. Diabetes Care
• (2019). Continuous Glucose Monitoring Versus Self-monitoring of Blood Glucose in Type 2 Diabetes Mellitus: A Systematic Review with Meta-analysis. Cureus
• (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. British medical journal
• (2012). Continuous glucose monitoring systems for type 1 diabetes mellitus. Cochrane Database of Systematic Reviews
• (2023). Efficacy and Safety of Continuous Glucose Monitoring and Intermittently Scanned Continuous Glucose Monitoring in Patients With Type 2 Diabetes: A Systematic Review and Meta-analysis of Interventional Evidence. Diabetes Care
• (2017). Continuous Glucose Monitoring vs Conventional Therapy for Glycemic Control in Adults With Type 1 Diabetes Treated With Multiple Daily Insulin Injections: The GOLD Randomized Clinical Trial. Journal of the American Medical Association (JAMA)