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Cost Effectiveness of Continuous Glucose Monitoring in Type 1 Diabetes

Jun 16, 2018

Data from DIAMOND trial to help determine the cost effectiveness of continuous glucose monitoring and whether it helps those with consistently high glucose.

With each year, the economic burden of diabetes care rises. In the span of five years, 2007 to 2012, the total cost of diabetes care increased from $174 billion to a staggering $245 billion. Given this fact, it is crucial that measures are taken to improve glycemic control and minimize diabetes costs.


When a patient with type 1 diabetes mellitus (T1DM) takes insulin, there are inherent risks, like the predisposition to hypoglycemia. These negative events can lead to a poorer quality of life and increased healthcare costs (i.e. hospitalizations, rescue medications, etc.). The reality is that these are major concerns for many people who have diabetes. So, how can you ensure your patient achieves glucose management and reaches those HbA1c targets? Well, it can be done with proper blood glucose monitoring. Some studies have found that traditional self-monitoring of blood glucose (SMBG), by a finger-stick, is beneficial but might not be the optimal monitoring method. Even when glucose testing is performed nine times per day, patients have been known to experience around 2 hours and 7 hours of hypoglycemia and hyperglycemia, respectively. When SMBG alone is not enough, continuous monitoring of blood glucose (CGM) is a great option for patients who have T1DM struggling to meet glycemic targets.

One study, Multiple Daily Injections and Continuous Glucose Monitoring in Diabetes (DIAMOND), evaluated CGM and concluded that glycemic control was improved compared to SMBG in patients with T1DM taking multiple daily insulin injections. Utilizing data from the DIAMOND trial, W. Wan et al sought to determine the cost-effectiveness of CGM in people with type 1 diabetes.

Enrollees of the study were randomized into either the CGM group or SMBG (2:1). Patients were stratified based on site and HbA1c (<8.5% and ≥8.5%). Patients were analyzed at baseline and after 6 months of CGM use. The following data was obtained at both visits: 1) health-related quality of life, 2) healthcare services used, 3) medications used, 4) test strip usage, 5) employment productivity, 6) hours spent on diabetes-related self-care. For more information on cost-effectiveness analysis (CEA) details, refer to Table 1: CEA Details.

Table 1: CEA Details
  • Societal

(U.S. Dollars in 2015)

Direct Clinical Personnel Cost:

  • Non-scheduled visits with clinical staff
  • CGM training and counseling
CGM Cost:

  • $15.20 per day (sensor, receive, transmitter)
Indirect Costs:

  • Number of missed work days due to T1DM
  • Underperformance at work
Non-CGM Medical Care Costs

  • Routine office visits
  • Urgent care visits
  • Emergency services utilized
Quality of Life
  • Used the 5-Level EuroQoL 5-Dimension (EQ-5D-5L) questionnaire
  • Quality-Adjusted Life Years (QALYs) – measure of health outcomes and disease burden – calculated
  • Incremental Cost-Effectiveness Ratio (ICER) – ratio of difference between groups in cost over QALYs
Non-severe Hypoglycemic Events
  • Every enrollee wore a CGM for blinding and to assess non-severe hypoglycemia (<54 mg/dL) for at least 20 minutes.

Note: Costs described in this table are is not comprehensive, more details can be found in the study’s research design and methods.

In total, 102 CGM participants and 53 control participants completed the study. Baseline characteristics showed that the CGM group was younger (p < 0.01). Looking at average 6-month cost, CGM was costlier at $11,032 compared to $7,236 for the control group (p < 0.01), with differences likely attributed to the cost of the device. No other cost differences were found (p > 0.4). CGM use showed a reduction in daily test strip use (p = 0.04), which led to lower test strip costs (CGM $612 vs Control $750). Additionally, the number of interactions with healthcare personnel were similar between both groups.

Clinical outcomes, including HbA1c, non-severe hypoglycemic events, vascular complications were evaluated. Overall, CGM usage showed larger reductions from baseline compared to control for both HbA1c (CGM -1.0 ± 0.8% vs Control -0.4 ± 0.7%; p < 0.01) and hypoglycemic events (CGM -0.12 ± 0.29 vs Control -0.06 ± 0.27; p = 0.02). Furthermore, patients in the high baseline HbA1c (≥8.5%) group using CGM devices, showed significant reductions from baseline (p < 0.01), however hypoglycemic events remained unchanged (p = 0.27). On the other hand, patients in the low baseline HbA1c (<8.5%) group showed reductions in both HbA1c and hypoglycemic event rates (p < 0.01; p = 0.03). The lifetime CEA, which follows the natural progression of a patient through T1DM (includes microvascular, macrovascular, hypoglycemia, hyperglycemia, etc.), found that CGM use is associated with lower incidence of major T1DM complications. Microvascular complications like blindness, end-stage renal disease, and amputation were found to be reduced. While macrovascular complications like myocardial infarction, stroke, and heart failure were lower in the CGM group.

In summary, the study aimed to evaluate the cost effectiveness of CGM in patients with T1DM with poor glycemic control. Wan et al found the CGM device, though costly, was incredibly useful in lowering HbA1c in patients not at target, reduced the test strip utilization per day, lowered test strip costs, and finally reduced the number of non-severe hypoglycemic events. By projecting CGM benefits over the lifetime of a person with type 1 diabetes, at a willingness-to-pay threshold of $100,000, CGM was found to be cost effective (ICER $98,108 per QALY and 0.54 QALYs gained).

Investigators concluded that most of the cost was attributed to the annual CGM costs, but stated that with extended use of the device and its components costs could be reduced (from $5,548 to $3,271, ICER reduces to $33,459 per QALY). Overall, CGM use might just be the best option for those struggling to achieve optimal glycemic and glucose control.

Practice Pearls:

  • Although CGM does not eliminate the use of traditional SMBG, continuous monitoring helps people with type 1 diabetes receiving multiple daily insulin injections patients achieve better glycemic and glucose control.
  • CGM devices can be a costly option, however use can allow patients to better attain control while lowering rates of non-severe hypoglycemic events thereby minimizing severe hypoglycemic events, which are often quite costly.
  • CGM use is associated with lower incidence of microvascular (i.e. blindness, amputation, etc.) and macrovascular (i.e. MI, stroke, etc.) complications.

Kaytie A. Weierstahl, Pharm.D. Candidate, LECOM School of Pharmacy


Wan, W., Skandari, M., Minc, A., Nathan, A., Winn, A., Zarei, P., O’Grady, M., and Huang, E. Cost-effectiveness of Continuous Glucose Monitoring for Adults With Type 1 Diabetes Compared With Self-Monitoring of Blood Glucose:  The DIAMOND Randomized Trial. Diabetes Care. 41 (2018):1227-1234. https://doi.org/10.2337/dc17-1821.