What does the long-term evidence show about the benefits?
The strongest evidence supports that GLP-1 receptor agonists produce substantial and sustained weight loss, improve blood sugar control, and reduce cardiovascular risks over periods of one to several years. In a 36-week randomized trial of the oral GLP-1 drug orforglipron, participants lost 9.4% to 14.7% of their body weight, compared to 2.3% with placebo [1]. A large analysis of over 215,000 people with diabetes found that GLP-1 use was linked to lower risks of heart attacks, strokes, and even neurocognitive disorders like dementia [8]. Another study in obese patients with atrial fibrillation showed that those on GLP-1 drugs had a 28% lower chance of needing repeat heart procedures or new medications over 12 months [7]. These findings are consistent across multiple large studies, suggesting the benefits are real and clinically meaningful.
What about the risks and side effects over the long term?
The long-term evidence also reveals some risks that patients and doctors need to weigh. The most common side effects are gastrointestinal (nausea, vomiting, diarrhea), which are usually mild to moderate and occur mainly when starting the drug [1]. More concerning are findings from a nationwide Danish study that followed people for up to 10 years: sustained GLP-1 use was associated with about 4 extra cancer cases per 100 people compared to another diabetes drug [4]. A separate French study found that using GLP-1 drugs for 1–3 years raised the risk of all thyroid cancers by 58% and medullary thyroid cancer by 78% [5]. However, the same Danish study also found that GLP-1 users were less likely to die without a prior cancer diagnosis, suggesting the cancer risk might partly reflect that people are living long enough to develop cancer [4]. The evidence on pregnancy safety is reassuring: a large multinational study found no large increase in birth defects compared to insulin [2].
Who benefits most, and under what conditions?
The evidence shows that people with obesity (especially those with a BMI over 30) and those with type 2 diabetes get the most consistent benefits. For example, patients with a BMI over 50 who used GLP-1 drugs before bariatric surgery lost significantly more weight (a 5.5-point BMI drop vs. 2.9 points) without increasing surgical complications [3]. In type 1 diabetes, a small study found that adding a long-acting GLP-1 drug for an average of 2 years improved blood sugar control (HbA1c dropped by 0.71%) and reduced hospitalizations for diabetic ketoacidosis [6]. The benefits appear to be strongest in people who stay on the medication long-term, but the cancer risk also seems to increase with longer use [4][5]. So the decision to use these drugs long-term should be individualized, balancing the clear metabolic and cardiovascular benefits against the small but real cancer risk.
About These Sources
This answer is built on 8 peer-reviewed studies — published from 2022 to 2025, 3 from 2024 or later, 5 in Q1 journals, collectively cited 985 times — selected as the most relevant from 9 studies that passed quality screening, drawn from 80 papers retrieved from a database of over 500 million.
Sources used in this answer
Daily Oral GLP-1 Receptor Agonist Orforglipron for Adults with Obesity
In a 36-week randomized trial, the oral GLP-1 drug orforglipron led to 9.4–14.7% weight loss vs. 2.3% with placebo, with gastrointestinal side effects being the most common.
Safety of GLP-1 Receptor Agonists and Other Second-Line Antidiabetics in Early Pregnancy
A large multinational cohort study found no large increased risk of major birth defects in infants exposed to GLP-1 agonists around conception compared to insulin.
Use of GLP-1 agonists in high risk patients prior to bariatric surgery: a cohort study
In patients with BMI >50, preoperative GLP-1 use led to significantly more weight loss (5.5 vs. 2.9 BMI points) without increasing surgical complications or time to surgery.
Long-term cancer risk in users of GLP-1 agonists in Denmark: a nationwide emulated trial.
A 10-year nationwide Danish study found that sustained GLP-1 use was linked to about 4 extra cancer cases per 100 people compared to another diabetes drug, but also fewer deaths without prior cancer.
GLP-1 Receptor Agonists and the Risk of Thyroid Cancer
A French nested case-control study found that GLP-1 use for 1–3 years was associated with a 58% higher risk of all thyroid cancers and a 78% higher risk of medullary thyroid cancer.
Evaluating the Efficacy and Safety of Long-Acting GLP-1 Receptor Agonists in T1DM Patients
In a small retrospective study of type 1 diabetes patients, adding a long-acting GLP-1 for an average of 2 years improved HbA1c by 0.71% and reduced diabetic ketoacidosis hospitalizations.
Long-Term Impact of GLP-1 Receptor Agonists on AF Recurrence After Ablation in Obese Patients.
In obese patients undergoing atrial fibrillation ablation, GLP-1 use was linked to a 28% lower risk of needing repeat procedures or new heart medications over 12 months.
Mapping the effectiveness and risks of GLP-1 receptor agonists
A large VA database study of over 215,000 diabetes patients found GLP-1 use was associated with reduced risks of heart disease, dementia, and several other conditions, but increased risks of gastrointestinal disorders and pancreatitis.