Combining the GLP-1 agonist dulaglutide with insulin degludec significantly reduced blood sugar swings and improved time-in-range compared to insulin alone, with appetite suppression lasting about three months.
100% TIR by day 10All patients on dulaglutide + insulin degludec achieved time-in-range ≥70% by day 10, versus 67% on insulin alone
What the researchers found
Patients receiving dulaglutide plus insulin degludec had significantly lower glucose variability across all measures (SDBG, MAGE, LAGE, and PPGE) compared to insulin degludec alone (all p<0.05). The combination group achieved time-in-range (TIR) targets much faster: by day 10, 100% had TIR ≥70% compared to only 67% in the control group.
Appetite decreased significantly at 1 week after starting dulaglutide but began to return by 3 months. At 6 months, 89.2% of patients in the combination group were still on dulaglutide, indicating strong persistence. TIR was significantly associated with preserved islet (beta cell) function.
Why it matters
Many type 2 diabetes patients on long-acting insulin still struggle with blood sugar spikes after meals and unpredictable fluctuations. This study shows that adding a GLP-1 agonist doesn't just lower average blood sugar — it specifically smooths out the dangerous peaks and valleys. The CGM data provides a granular, real-world view of how quickly the combination works, which is valuable information for both patients and clinicians deciding whether to add a GLP-1 drug to existing insulin therapy.
How the study worked
This was a retrospective study of 236 adults with type 2 diabetes. The experimental group received once-weekly dulaglutide combined with daily insulin degludec, while the control group received insulin degludec alone. Researchers tracked patients for up to 6 months, using continuous glucose monitoring (CGM) data to measure blood sugar fluctuations and time in range. Appetite was assessed using standardized scoring at multiple time points.
What this study cannot tell us
This was a retrospective study, not a randomized controlled trial, so there may be selection bias in who received the combination therapy. The study did not report baseline characteristics in detail or adjust for confounders. Appetite was assessed by scoring rather than objective measures. The relatively short 6-month follow-up limits conclusions about long-term outcomes, and the study population may not be generalizable to all type 2 diabetes patients.
How to read the evidence
This is a retrospective observational study with 236 patients. While it provides useful real-world data with objective CGM measurements, the non-randomized design and potential for selection bias place it below randomized controlled trials in the evidence hierarchy.
When this study was published
Published in 2023, this study reflects current clinical practice patterns. The combination of GLP-1 agonists with basal insulin is an established and growing treatment approach.
The bigger picture
This study supports the growing trend toward combining GLP-1 receptor agonists with basal insulin rather than adding mealtime insulin. Fixed-ratio combinations of GLP-1 agonists with insulin (like iGlarLixi and IDegLira) are already available, and data like this reinforces why that approach works: the GLP-1 component handles post-meal glucose control and reduces appetite while the basal insulin manages fasting levels. The finding that appetite suppression wanes by 3 months is consistent with other GLP-1 research showing partial tolerance to the appetite effects.
Questions still open
- Does the appetite-suppressing effect of dulaglutide fully return after 3 months, or does some residual benefit persist at higher doses?
- Would the glucose variability benefits be even greater with newer, more potent GLP-1 agonists like semaglutide or tirzepatide?
- How does preserved beta cell function influence long-term outcomes in patients on this combination therapy?
Common questions
How quickly does adding dulaglutide to insulin improve blood sugar control?
Does dulaglutide permanently reduce appetite?
Read the original research
Effects of dulaglutide combined with insulin degludec on glucose fluctuations and appetite in type 2 diabetes.
Frontiers in endocrinology, 14, 1130470
Citation
Huang, Jinxin; Hua, Fei; Jiang, Xiaohong; Zhang, Xingguang; Yang, Minxing; Wang, Long; Huang, Xiaolin; Luo, Kaiming. (2023). Effects of dulaglutide combined with insulin degludec on glucose fluctuations and appetite in type 2 diabetes.. Frontiers in endocrinology, 14, 1130470. https://doi.org/10.3389/fendo.2023.1130470