TOPLINE

In a real-world study of adults with type 1 diabetes (T1D) followed for 5 years, patients whose continuous glucose monitoring (CGM)-derived time in range (TIR) declined by at least 10 percentage points developed microvascular complications more often than those with stable or improved TIR. Furthermore, CGM metrics such as TIR and glucose management indicator (GMI) performed about as well as A1c at distinguishing patients with microvascular complications from those without.

METHODOLOGY

• Although A1c is the standard measure of long-term glucose control, it misses day-to-day glucose swings, which CGM tracks through metrics such as TIR; however, long-term data linking the CGM-derived metrics to microvascular complications in T1D remain limited.
• To examine this, researchers conducted a real-world study in Belgium involving 246 adults with T1D (median age, 40 years; 50.4% women) who were free of microvascular complications at baseline and were recruited from three earlier CGM studies conducted between 2014 and 2021.
• They collected demographic and clinical data — including A1c, lipids, BMI, and blood pressure — at baseline and 60 months. CGM data were derived from each participant's ambulatory glucose profile over the preceding 28 days before each visit; more than 70% sensor wear time was required for the CGM data to be included.
• Participants were sorted by 5-year TIR trajectory: stable/minimal change (± 10 percentage points), meaningful improvement (≥ 10-point gain), or meaningful decline (≥ 10-point loss).
• The primary endpoint was a composite of nephropathy, severe retinopathy, and peripheral neuropathy at 5 years.

TAKEAWAY

• Microvascular complications occurred in 34 patients (13.8%), including severe retinopathy (n = 23), nephropathy (n = 8), and peripheral neuropathy (n = 8).
• At baseline, patients who later developed microvascular complications were older (P = .002) and had higher A1c (P = .024), mean glucose (P = .007), and GMI (P = .005), along with lower time in tight range (P = .004), though TIR itself did not differ; at 5-year follow-up, they also showed significant divergence in BMI (P = .032), systolic blood pressure (P < .001), A1c (P = .004), TIR (P = .002), time above range (P = .007), and GMI (P = .003).
• Microvascular complications developed more often in those whose TIR fell by at least 10 percentage points (33.3%) than in those who had stable TIR (7.9%) or improved TIR (15.0%); analysis of each complication separately showed that retinopathy, nephropathy, and peripheral neuropathy followed the same pattern, with rates highest in the TIR decline group.
• After adjusting for age and baseline A1c, change in TIR remained independently linked to microvascular complications; across three models incorporating A1c, TIR, and GMI, all three metrics performed similarly well at predicting microvascular complications.

IN PRACTICE

"[G]lucometric data showed discriminative ability comparable to that of HbA1c, suggesting a potential complementary role for CGM-based metrics in clinical practice, for instance in situations where HbA1c is unavailable or has not yet been measured," the authors wrote.

SOURCE

The study was led by Amber Sabbe, Antwerp University Hospital & University of Antwerp in Edegem, Belgium. It was published online in The Journal of Clinical Endocrinology & Metabolism.

LIMITATIONS

The study group was fairly small, and splitting patients into subgroups based on their TIR changes made each group even smaller. Some glucose metrics (GMI and time in tight range) had missing data for a number of patients. The study duration may not have been long enough to evaluate the development of complications.

DISCLOSURES

Several authors disclosed receiving consulting fees, honoraria, research support, travel support, or advisory board payments from various pharmaceutical and medical device companies. Some also reported serving as consultants or members of speakers bureaus.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.