In the 4,712-patient GRADE trial, liraglutide preserved insulin-producing beta-cell function better than glimepiride, sitagliptin, or insulin glargine over 5 years, though all treatments showed eventual decline.
Liraglutide: best β-cell preservation at 5 yearsAmong four diabetes treatments in 4,712 patients, the GLP-1 RA liraglutide maintained insulin secretion and glucose sensitivity above baseline values the longest, though even it could not prevent eventual decline.
What the researchers found
In the GRADE trial comparing four diabetes treatments added to metformin, liraglutide (the GLP-1 RA) produced the greatest improvements in beta-cell function. Liraglutide led to the largest increases in insulin secretion rate, glucose sensitivity, and potentiation, with values remaining above baseline even after 5 years. Sitagliptin improved glucose sensitivity with modest other effects. Glimepiride temporarily boosted insulin secretion but minimally affected glucose sensitivity. All treatments showed beta-cell function improvements at year 1 followed by progressive decline, and lower beta-cell function predicted earlier glycemic failure regardless of treatment.
Why it matters
Beta-cell decline is the core driver of type 2 diabetes progression. This analysis of the landmark GRADE trial reveals that liraglutide — a GLP-1 peptide drug — preserves beta-cell function better than three other major diabetes medications over 5 years. Despite this advantage, beta-cell function still declined with all treatments, highlighting that even the best available therapies cannot fully halt diabetes progression. Understanding how different drugs affect beta-cell physiology helps guide treatment selection.
The numbers in context
n=4,712 · 4 treatment arms · 5-year follow-up · liraglutide had greatest ISR, glucose sensitivity, and potentiation increases · all treatments showed year 1 improvement then decline · glycemic failure defined as HbA1c >7.5%
How the study worked
This analysis used data from the GRADE trial, a large comparative effectiveness study that randomized 4,712 adults with type 2 diabetes to insulin glargine, glimepiride, liraglutide, or sitagliptin added to metformin. Beta-cell function was assessed using mathematical modeling of oral glucose tolerance tests at baseline and years 1, 3, and 5. Linear mixed-effects models compared treatment effects, and Cox proportional hazards and CART analyses evaluated associations with glycemic failure.
Who was studied
4,712 adults with type 2 diabetes on metformin, randomized to one of four add-on treatments in the GRADE trial
What this study cannot tell us
Beta-cell function was assessed via oral glucose tolerance test modeling rather than direct beta-cell measurements. The study cannot determine whether liraglutide's beta-cell benefits are direct effects on beta cells or secondary to improved metabolic conditions. The progressive decline in beta-cell function with all treatments suggests none fundamentally alters the disease trajectory.
How to read the evidence
This is a secondary analysis from the GRADE trial, a large, well-designed, randomized comparative effectiveness study with 4,712 participants and 5 years of follow-up. The evidence quality is high, though the observational nature of the beta-cell function analysis limits causal conclusions.
When this study was published
Published in 2025 using data from the GRADE trial (randomized 2013-2017, follow-up through 2021), this analysis provides mature, long-term data on how GLP-1 therapy affects beta-cell function.
The bigger picture
The GRADE trial is one of the most important comparative effectiveness studies in type 2 diabetes. This beta-cell function analysis provides the mechanistic explanation for why liraglutide performed well in the main trial — it does the most to support the failing pancreatic beta cells. The finding that even liraglutide cannot prevent eventual decline underscores the need for interventions that truly halt or reverse beta-cell loss, an area where newer peptide-based combination therapies are being explored.
Questions still open
- Would newer GLP-1 agonists like semaglutide or the dual GIP/GLP-1 agonist tirzepatide show even better beta-cell preservation than liraglutide?
- Does liraglutide's beta-cell benefit come from direct cellular effects or from reducing metabolic stress (glucotoxicity, lipotoxicity)?
- Could earlier initiation of GLP-1 therapy — before significant beta-cell decline — better preserve long-term pancreatic function?
Common questions
Why is beta-cell function so important in type 2 diabetes?
If liraglutide best preserves beta-cell function, why do patients still experience decline?
Read the original research
Differential Treatment Effects on β-Cell Function Using Model-Based Parameters in Type 2 Diabetes: Results From the Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness Study (GRADE).
Diabetes care, 48(4), 623-631
Citation
Utzschneider, Kristina M; Tripputi, Mark; Butera, Nicole M; Mari, Andrea; Rosin, Samuel P; Banerji, Mary Ann; Bergenstal, Richard M; Brown, Necole; Carlson, Anders L; DeFronzo, Ralph A; Gramzinski, Michaela R; Harindhanavudhi, Tasma; Kozedub, Alexandra; Sivitz, William I; Steffes, Michael W; Balasubramanyam, Ashok; Rasouli, Neda. (2025). Differential Treatment Effects on β-Cell Function Using Model-Based Parameters in Type 2 Diabetes: Results From the Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness Study (GRADE).. Diabetes care, 48(4), 623-631. https://doi.org/10.2337/dc24-2419