GLP-1 Medications and Insulin Resistance: What the Research Shows

If you have been told your blood sugar is higher than it should be, or that you are showing signs of metabolic syndrome, you have probably heard the phrase "insulin resistance." What you may not know is how directly this condition intersects with the conversation around GLP-1 medications like semaglutide and tirzepatide.

These medications were developed primarily to address obesity and type 2 diabetes. But the metabolic effects they produce, including their impact on how your body handles insulin, are part of what makes them significant beyond simple weight reduction. This article explains what insulin resistance is, how GLP-1 medications interact with it at a biological level, and what the clinical evidence tells us.

*Compounded semaglutide and compounded tirzepatide are not FDA-approved. This article is for educational and informational purposes only and does not constitute medical advice. Clinical trial data cited here refers to FDA-approved branded products; results should not be assumed to apply to compounded formulations. Individual results vary. Consult your licensed healthcare provider before starting, stopping, or adjusting any medication or treatment. Care at Prescriva is delivered by independently licensed providers, not by Blue Oak Services LLC dba Prescriva, which is a management services organization.*

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Understanding Insulin Resistance

Insulin is a hormone produced by the pancreas. Its job is to act as a key that unlocks your cells, allowing glucose from your bloodstream to enter and be used for energy. When your cells stop responding efficiently to insulin's signal, the pancreas compensates by producing more of it. This state, where your body requires more insulin than normal to move the same amount of glucose, is called insulin resistance.

Over time, if the pancreas cannot keep up with the demand, blood glucose levels begin to rise. This progression leads from normal metabolism to prediabetes and eventually to type 2 diabetes for many people. Along the way, insulin resistance also contributes to weight gain (particularly around the abdomen), high blood pressure, elevated triglycerides, low HDL cholesterol, and increased cardiovascular risk. Together, these are often described as metabolic syndrome.

The drivers of insulin resistance include excess body weight (especially visceral fat stored around the organs), physical inactivity, chronic sleep deprivation, chronic inflammation, and genetic predisposition. Reducing visceral fat is one of the most reliable ways to improve insulin sensitivity.

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How GLP-1 Medications Work on Insulin Resistance

GLP-1 receptor agonists like semaglutide and tirzepatide affect insulin resistance through several biological pathways. These are not interchangeable or redundant. Each one contributes something distinct.

Weight Loss as the Primary Driver

The most consistent finding across GLP-1 clinical trials is that significant weight reduction, particularly loss of visceral and ectopic fat, leads to meaningful improvement in insulin sensitivity. Visceral fat is metabolically active in ways that promote inflammation and disrupt insulin signaling. When you reduce it, you directly reduce the biological noise that causes cells to become resistant.

GLP-1 medications produce weight loss by acting on receptors in the brain that regulate appetite and satiety, slowing gastric emptying so meals feel more satisfying, and reducing caloric intake. The resulting weight loss is not marginal. Clinical trials in adults with obesity have shown average losses in the range of 15 to 21 percent of body weight depending on the medication and dose. That level of weight loss has predictable and substantial effects on metabolic markers.

Reducing Liver Fat

One of the more underappreciated pathways involves the liver. People with insulin resistance commonly accumulate excess fat in liver cells, a condition called metabolic-associated steatotic liver disease (MASLD). This hepatic fat directly impairs the liver's ability to regulate blood glucose, contributing to what is called hepatic insulin resistance.

GLP-1 medications have been shown to reduce liver fat. This occurs partly through caloric restriction driven by reduced appetite and partly through direct mechanisms that affect how the liver processes fats. When liver fat decreases, hepatic insulin resistance improves. The liver becomes more responsive to insulin's instruction to suppress glucose output between meals, which is an important component of overall glycemic control.

Improving Beta Cell Function

GLP-1 receptors are present on the insulin-secreting beta cells of the pancreas. When GLP-1 receptors are activated after a meal, they amplify insulin secretion in a glucose-dependent manner. Crucially, this amplification only occurs when blood glucose is elevated. When glucose levels are normal or low, the effect tapers off, which is why GLP-1 medications carry a low risk of causing hypoglycemia on their own.

In people with insulin resistance, the beta cells are often working overtime to compensate. Over time, this stress can impair beta cell function. By reducing the metabolic burden through weight loss and liver fat reduction, GLP-1 medications help the beta cells operate more efficiently rather than continuously at maximum demand.

Anti-Inflammatory Effects

Chronic low-grade inflammation is both a cause and a consequence of insulin resistance. Inflammatory signaling molecules (cytokines like TNF-alpha and IL-6) interfere with insulin receptor signaling directly. Visceral fat is a primary source of these inflammatory signals.

As visceral fat decreases with GLP-1-driven weight loss, the inflammatory burden on the metabolic system also decreases. Some research suggests that GLP-1 receptors may also have direct anti-inflammatory effects independent of weight loss, though this area is still being characterized in ongoing studies.

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What Clinical Trials Show

The evidence base for GLP-1 medications and metabolic health is substantial. The key trials help illustrate what is actually happening at a population level.

Semaglutide: STEP 1 and SELECT

The STEP 1 trial (PMID: 33567185, Wilding JP et al., *New England Journal of Medicine*, 2021) enrolled 1,961 adults with obesity or overweight with at least one weight-related complication but without type 2 diabetes. Participants received once-weekly semaglutide 2.4 mg or placebo alongside lifestyle intervention.

After 68 weeks, semaglutide produced a mean weight loss of 14.9 percent of body weight compared to 2.4 percent in the placebo group. Alongside weight reduction, participants in the semaglutide group showed greater improvements across cardiometabolic risk factors including blood pressure, lipids, and glycemic markers. The improvements in these metabolic indicators are consistent with a meaningful improvement in the underlying insulin resistance that connects excess weight to cardiovascular and metabolic disease.

The SELECT trial (PMID: 37952131, Lincoff AM et al., *New England Journal of Medicine*, 2023) took the question further by enrolling 17,604 adults with established cardiovascular disease and obesity, but no diabetes, and following them for a median of approximately 40 months. The semaglutide group showed a 20 percent reduction in major cardiovascular events compared to placebo. This population, by definition, carried high insulin resistance burden. The cardiovascular benefit extended beyond what weight loss alone typically produces, suggesting that the metabolic effects of semaglutide, including its impact on insulin resistance pathways, contribute to outcomes in a meaningful way.

Tirzepatide: SURMOUNT-1 and SURPASS-1

The SURMOUNT-1 trial (PMID: 35658024, Jastreboff AM et al., *New England Journal of Medicine*, 2022) enrolled 2,539 adults with obesity or overweight without diabetes. Participants received tirzepatide at 5 mg, 10 mg, or 15 mg weekly or placebo for 72 weeks. Mean weight loss across doses ranged from 15.0 percent to 20.9 percent. All doses of tirzepatide produced improvements across prespecified cardiometabolic measures. The degree of weight loss achieved in this trial was substantially greater than that seen in earlier semaglutide trials, and the cardiometabolic improvements tracked accordingly.

For patients who already have type 2 diabetes, the SURPASS-1 trial (PMID: 34186022, Rosenstock J et al., *Lancet*, 2021) provides additional context. SURPASS-1 enrolled patients with type 2 diabetes and tested tirzepatide against placebo over 40 weeks. HbA1c reductions ranged from 1.87 to 2.07 percentage points across doses, with 87 to 92 percent of tirzepatide patients reaching an HbA1c target below 7.0 percent compared to 20 percent on placebo. Between 31 and 52 percent of patients reached HbA1c levels below 5.7 percent, a threshold consistent with normoglycemia. These are not incremental improvements. They represent a fundamental shift in how the metabolic system is functioning.

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Tirzepatide's Dual Mechanism and the GIP Advantage

Tirzepatide is structurally different from semaglutide in a clinically meaningful way. Where semaglutide activates only GLP-1 receptors, tirzepatide activates both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptors simultaneously.

GIP receptors are expressed in adipose tissue, particularly in fat cells. When GIP receptors in fat tissue are activated, they appear to influence how fat is stored and released, potentially shifting fat distribution away from visceral deposits. This mechanism may partly explain why tirzepatide consistently produces greater weight loss than semaglutide in trials, and why its effects on metabolic markers tend to be more pronounced at comparable time points.

Importantly, the superior weight loss in the SURMOUNT-1 trial compared to STEP 1 was not driven entirely by different trial designs. The head-to-head data from SURMOUNT-5 (PMID: 40353578, Aronne LJ et al., *New England Journal of Medicine*, 2025) confirmed that tirzepatide produces significantly greater weight loss than semaglutide in a direct comparison, with tirzepatide achieving 20.2 percent mean weight loss versus 13.7 percent for semaglutide at 72 weeks. Because weight loss is the primary driver of insulin resistance improvement in this class, the greater magnitude of weight loss with tirzepatide translates to a greater metabolic impact.

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Who Should Talk to Their Provider About GLP-1 Medications

GLP-1 medications are not appropriate for everyone, and a licensed provider needs to evaluate your individual situation. That said, people who tend to benefit most from the metabolic effects of these medications include:

• Adults with a BMI of 30 or higher, or BMI of 27 or higher with a weight-related condition like high blood pressure, prediabetes, or elevated cholesterol
• People with prediabetes who want to reduce their progression risk
• Adults with metabolic syndrome characterized by a cluster of insulin resistance-related findings
• People with type 2 diabetes who are looking for weight loss alongside glycemic control
• Adults with PCOS (polycystic ovary syndrome), where insulin resistance is a central driver of hormonal disruption

Independently licensed healthcare providers in Prescriva's affiliated network require a medical consultation before prescribing. Compounded semaglutide and tirzepatide are prescribed based on your individual clinical picture, not as an over-the-counter product.

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What to Realistically Expect

Managing expectations is important. GLP-1 medications are not insulin sensitizers in the same direct sense as metformin or thiazolidinediones (TZDs), which act on insulin signaling pathways in muscle and liver. The improvements in insulin resistance seen with GLP-1 medications are primarily mediated through weight loss and the downstream effects of losing visceral and hepatic fat.

This means the degree of metabolic improvement you experience is closely tied to how much weight you lose and how much visceral fat you shed. People who lose more weight generally see more substantial improvements in blood sugar, blood pressure, lipids, and other markers of insulin resistance.

It also means that lifestyle factors still matter. Dietary quality and physical activity influence how much of your weight loss comes from fat versus lean tissue, which in turn affects metabolic outcomes. Independently licensed healthcare providers in Prescriva's affiliated network approach treatment as a combination of medication and lifestyle modification, not medication alone.

Most people do not see dramatic metabolic changes in the first few weeks. The improvements tend to accumulate over months as weight loss progresses and metabolic adaptations occur.

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Frequently Asked Questions

Can GLP-1 medications reverse insulin resistance? In many cases, yes, meaningful improvement is achievable. Whether this constitutes "reversal" depends on the individual and how much weight is lost. People who lose 15 percent or more of their body weight often see substantial normalization of metabolic markers.

Will my doctor prescribe a GLP-1 medication just for insulin resistance without diabetes? Possibly, depending on your clinical picture. Many providers consider prediabetes, metabolic syndrome, or elevated cardiovascular risk alongside obesity to be sufficient clinical grounds. The specific indications depend on your provider's assessment.

Are the improvements sustained if I stop the medication? Generally, weight and metabolic markers tend to return toward baseline if the medication is discontinued without sustained lifestyle changes. This is consistent with how the medications work: they support a metabolic environment that depends on ongoing treatment.

Does tirzepatide work better than semaglutide for insulin resistance? Tirzepatide tends to produce greater weight loss, which is the primary driver of insulin resistance improvement. Whether that translates to meaningfully better metabolic outcomes for any specific individual depends on how they respond, which varies. Your provider can help you evaluate which medication may be appropriate.

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Ready to Explore Your Options?

If you are managing insulin resistance, prediabetes, or metabolic syndrome and want to understand whether a GLP-1 medication might be appropriate for your situation, the first step is a medical consultation. Licensed healthcare providers in Prescriva's affiliated network can review your health history and help determine whether compounded semaglutide or tirzepatide fits your clinical picture.

[Check your eligibility](/get-started)

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*This article is for educational and informational purposes only. It does not constitute medical advice. Compounded semaglutide and compounded tirzepatide are not FDA-approved. They have not been evaluated by the FDA for safety, efficacy, or quality. Individual results vary and are not guaranteed. Outcomes from branded clinical trials (Ozempic, Wegovy, Mounjaro, Zepbound) are cited for educational context and should not be assumed to apply to compounded formulations. Blue Oak Services LLC dba Prescriva is a management services organization (MSO). Medical care is provided by independently licensed healthcare providers, not by Prescriva. Ozempic and Wegovy are registered trademarks of Novo Nordisk. Mounjaro and Zepbound are registered trademarks of Eli Lilly and Company.*

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Sources

1. Wilding JP, Batterham RL, Calanna S, et al. "Once-Weekly Semaglutide in Adults with Overweight or Obesity." *N Engl J Med.* 2021;384(11):989-1002. PMID: 33567185
2. Jastreboff AM, Aronne LJ, Ahmad NN, et al. "Tirzepatide Once Weekly for the Treatment of Obesity." *N Engl J Med.* 2022;387(3):205-216. PMID: 35658024
3. Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. "Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes." *N Engl J Med.* 2023;389(24):2221-2232. PMID: 37952131
4. Rosenstock J, Wysham C, Frias JP, et al. "Efficacy and Safety of a Novel Dual GIP and GLP-1 Receptor Agonist Tirzepatide in Patients with Type 2 Diabetes (SURPASS-1)." *Lancet.* 2021;398(10295):143-155. PMID: 34186022
5. Aronne LJ, Sattar N, Horn DB, et al. "Continued Treatment with Tirzepatide for Maintenance of Weight Reduction in Adults with Obesity." *N Engl J Med.* 2025;392(5):418-428. PMID: 40353578