Comisair Study - What's New

Background & Rationale

Type 1 diabetes management has two central pillars:

Insulin delivery — via multiple daily injections (MDI) or via continuous subcutaneous insulin infusion (CSII, i.e. insulin pump).

Glucose monitoring — standard self-monitoring of blood glucose (SMBG) via fingerprick testing, or more modern continuous glucose monitoring (CGM) systems (which can provide real-time data, trends, alerts, etc.).

Historically, insulin pump therapy (CSII) was often portrayed as superior to MDI by virtue of more flexibility, finer basal control, and ease of bolus adjustments. Meanwhile, CGM was increasingly shown to help reduce hypoglycemia and provide better awareness of glucose trends. However, few studies had rigorously compared the combination of monitoring and delivery modes in a head-to-head fashion over a long period under real-world conditions, especially parsing out how much benefit came from better monitoring as distinct from the insulin delivery approach.

Enter COMISAIR: this study was designed to prospectively follow patients who chose different combinations of these modalities, and to evaluate which aspects (monitoring or delivery) drive the improvements in glycemic outcomes.

Study Design & Methods (1-Year Trial)

The original COMISAIR study followed 65 adults with T1D for one year. Participants were grouped based on their chosen management approach:

SAIR (Sensor-Augmented Insulin Regimen) group – used real-time CGM. Within this, some patients used insulin pumps (SAP) while others continued MDI with CGM.

CSII group – used insulin pumps but no CGM.

MDI + SMBG group – used multiple injections with standard finger-prick glucose monitoring.

The study’s goal was to compare changes in HbA₁c, glycemic variability, and rates of hypoglycemia across these combinations.

One-Year Results

After one year, the results were striking:

HbA₁c Reduction:

Participants using CGM (both MDI and pump users) saw significant HbA₁c reductions from about 8.3% to 7.1%. In contrast, those using insulin pumps without CGM improved only slightly, and those using injections with finger-prick monitoring saw almost no change.

Glycemic Variability:

Both CGM groups experienced more stable blood sugar levels with fewer swings throughout the day.

Hypoglycemia:

Episodes of low blood sugar decreased significantly among CGM users, while rates remained unchanged in other groups.

These findings showed that the key driver of improvement was CGM use, not necessarily the insulin pump. Patients who continued injections but adopted CGM achieved similar outcomes to those using pumps.

Three-Year Follow-Up

COMISAIR extended its analysis to three years, this time following 94 adults divided into four groups:

CGM + MDI

CGM + CSII

SMBG + MDI

SMBG + CSII

After three years, both CGM groups maintained superior HbA₁c levels, averaging around 7.0%, compared to 7.7% and 8.0% in the SMBG groups.

The improvement in Time in Range (TIR) — the percentage of time blood glucose stayed between 70–180 mg/dL — was dramatic. TIR increased from roughly 50% to over 70% in the CGM groups, while the SMBG groups showed no comparable progress.

Severe hypoglycemia episodes were also notably lower among CGM users. These findings reaffirmed that the type of glucose monitoring was more influential than the method of insulin delivery.

Clinical Implications

The COMISAIR study has reshaped modern diabetes management by proving that continuous glucose monitoring is not just an add-on tool—it’s a critical component of effective diabetes care.

Key takeaways for healthcare providers and patients include:

CGM is transformative – It offers better glycemic control and safety than finger-prick testing.

MDI + CGM is as effective as pump + CGM – Making advanced monitoring accessible even to those who prefer or can only afford injections.

Pump therapy adds convenience, but CGM drives the largest share of clinical benefit.

Long-term CGM use leads to lasting improvements in HbA₁c and reduced hypoglycemia risk.

Policy makers and insurers should consider CGM coverage essential for all people with type 1 diabetes.

𝐒𝐞𝐯𝐞𝐧-𝐘𝐞𝐚𝐫 𝐎𝐮𝐭𝐜𝐨𝐦𝐞𝐬

In follow-up studies spanning seven years, researchers found the benefits of CGM persisted over time. Participants who consistently used CGM continued to show:

Sustained reductions in HbA₁c

Higher Time in Range (above 70%)

Fewer severe hypoglycemia incidents

Possible lower risk of diabetes-related complications, such as retinopathy

This long-term data further strengthened the argument that CGM plays a crucial role in maintaining consistent blood sugar control and improving overall diabetes outcomes.

𝐒𝐭𝐫𝐞𝐧𝐠𝐭𝐡𝐬 𝐚𝐧𝐝 𝐋𝐢𝐦𝐢𝐭𝐚𝐭𝐢𝐨𝐧𝐬

Strengths:

Real-world, prospective design that reflects everyday patient experiences.

Direct comparison between CGM and SMBG across both MDI and pump users.

Long-term follow-up demonstrating the durability of CGM benefits.

Limitations:

The study was nonrandomized, meaning patients selected their preferred treatment mode, potentially introducing bias.

The sample size was moderate, limiting the ability to detect subtle subgroup differences.

Conducted in a single clinical setting, which may limit generalizability.

Devices used have evolved significantly since the study began, meaning modern technology could produce even greater benefits.

𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧

The COMISAIR study is one of the most influential real-world investigations into diabetes technology to date. Its consistent findings over one, three, and seven years confirm that continuous glucose monitoring is the cornerstone of effective diabetes management. Whether paired with injections or insulin pumps, CGM helps patients achieve better control, safety, and quality of life.

By distinguishing the effects of monitoring from insulin delivery, COMISAIR has paved the way for more personalized, affordable, and technology-driven approaches to diabetes care.