Is Rosemary Good for Diabetes? Benefits and Risks

Rosemary shows genuine promise as a blood-sugar-friendly herb, but the honest picture is more nuanced than many wellness sites suggest. Lab studies and animal experiments have consistently found that rosemary’s active compounds can lower blood glucose through several distinct mechanisms, and a small number of human studies report meaningful drops in fasting blood sugar and long-term glucose markers in people with type 2 diabetes. The gap between those encouraging signals and a confident clinical recommendation remains wide, though, because large-scale human trials are still missing. Here is what the research actually shows, where it falls short, and what the practical implications are if you have diabetes or are at risk for it.

What Makes Rosemary Relevant to Blood Sugar

Rosemary is not just a kitchen herb with a pleasant aroma. It is packed with bioactive polyphenols, and the ones that matter most for blood sugar are carnosic acid, rosmarinic acid, and carnosol. These compounds have shown antioxidant, anti-inflammatory, and blood-sugar-lowering properties across a wide range of laboratory experiments.¹ A review in Current Opinion in Food Science concluded that these active components could function as dietary ingredients for managing chronic conditions like obesity and diabetes.²

The fact that rosemary has been used in traditional medicine around the Mediterranean and beyond for centuries adds context but does not, by itself, prove anything. What moves the needle is that modern research has been able to identify specific compounds and trace their effects on glucose metabolism at the cellular level. That mechanistic clarity is what separates rosemary from herbs that rely entirely on folklore.

How Rosemary Compounds Lower Blood Sugar

The blood-sugar-lowering effects of rosemary work through at least three distinct pathways, which is part of why researchers find it interesting. Most pharmaceutical drugs target one mechanism. Rosemary’s compounds hit several at once.

The first is enzyme inhibition. When you eat carbohydrates, enzymes in your gut break starches into simple sugars that then enter your bloodstream. Rosemary extract inhibits two key enzymes involved in that process, slowing the rate at which sugar enters the blood after a meal. Lab testing found rosemary to be a potent inhibitor of both of these starch-digesting enzymes, as well as the enzyme that breaks down dietary fat.³ This is the same basic strategy used by certain prescription diabetes medications that slow carbohydrate absorption.

The second pathway involves how muscle cells take up glucose. In a study using muscle cell cultures, rosemary extract stimulated glucose uptake to about 184% of baseline levels, which was in the same ballpark as the response to insulin itself (about 207%) and metformin (about 216%). The extract worked through an energy-sensing pathway called AMPK rather than through the insulin signaling pathway, meaning it could potentially help even when insulin signaling is impaired, as it is in type 2 diabetes.⁴

The third pathway is anti-inflammatory. Chronic low-grade inflammation plays a major role in insulin resistance, which is the hallmark of type 2 diabetes. Carnosic acid, one of rosemary’s key compounds, has been shown to dampen the inflammatory signals that make fat cells resistant to insulin. In cell studies, it blocked the chain of molecular events that leads from inflammation to impaired insulin signaling.⁵

On top of all this, rosmarinic acid has been shown to protect the insulin-producing cells of the pancreas from oxidative damage in diabetic rats. Histological examination confirmed that oral dosing with rosmarinic acid preserved the structure of these cells in animals fed a high-fat diet and given a diabetes-inducing agent.⁶ If this translates to humans, it could mean rosemary not only helps manage blood sugar in the short term but also slows the progressive loss of insulin production that worsens type 2 diabetes over time. That is a meaningful “if,” though.

What Human Studies Show

This is where the excitement needs to be tempered. The vast majority of rosemary-and-diabetes research has been conducted in cells and animals. Human evidence exists but is thin. The most cited human study involved type 2 diabetic patients already taking standard medications. Patients on one common diabetes drug who added rosemary saw their fasting blood glucose and HbA1c (a marker of long-term blood sugar control) drop by roughly 16 to 18%, while patients on a combination of two drugs saw those markers drop by about 23%. The rosemary group also showed increased vitamin B12 levels, which is relevant because one widely used diabetes drug is known to deplete B12.⁷

Those numbers are encouraging, but a single small study is not the kind of evidence you build treatment guidelines on. The study was not placebo-controlled, and participants knew what they were taking. The findings need replication in larger, better-designed trials before anyone can say with confidence how much rosemary truly helps in a real-world clinical setting. A review of both preclinical and clinical data confirmed that rosemary extracts and carnosic acid can improve fasting glucose and HbA1c, but the same review underscored the need for more rigorous human research.⁸

What this means practically: if you have diabetes, rosemary is not a substitute for your prescribed treatment. But the evidence does suggest it is more than just a pleasant seasoning. As an addition to your existing regimen, the existing data are at least plausible enough to warrant interest, even if not yet strong enough to warrant specific dosing recommendations.

Effects on Cholesterol and Metabolic Markers

Diabetes rarely travels alone. Most people with type 2 diabetes also have abnormal cholesterol levels, and cardiovascular disease is the leading cause of death in this population. Rosemary appears to offer some benefit here as well. In one study, participants who consumed rosemary leaf powder at varying doses showed significantly lower total cholesterol and triglycerides across all dosing groups. Those taking the highest dose (10 grams per day) also saw a significant drop in LDL (“bad”) cholesterol and a significant rise in HDL (“good”) cholesterol.⁹

Again, this is a single study, and 10 grams of rosemary powder per day is a substantial amount. But the direction of the findings aligns with what the lab research on rosemary’s antioxidant and anti-inflammatory properties would predict. For someone managing both diabetes and high cholesterol, the combination of glucose-lowering and lipid-improving effects makes rosemary an interesting dietary addition, not as a drug replacement but as part of a broader metabolic strategy.

Protection Against Diabetic Complications

Some of the most intriguing rosemary research has nothing to do with blood sugar directly and everything to do with what prolonged high blood sugar does to the body. One of the most damaging consequences of chronic hyperglycemia is the formation of advanced glycation end-products, often shortened to AGEs. These are sticky, dysfunctional molecules formed when sugars bind to proteins, and they accumulate in blood vessels, kidneys, eyes, and nerves, driving the complications that make diabetes so dangerous over time.

In laboratory models, both rosmarinic acid and carnosic acid blocked the formation of AGEs with striking effectiveness. At higher concentrations, they inhibited certain types of AGEs by more than 90%.¹⁰ A separate study using different glycation models confirmed that rosemary extracts possess potent anti-glycation activity across multiple systems, leading the authors to call rosemary “an excellent multifunctional therapeutic herb” with potential as an adjuvant for preventing diabetic and cardiovascular complications.¹¹

These are test-tube experiments, and AGE formation in the human body is more complex than in a dish. Still, the magnitude of the inhibition and the consistency across different models make this one of the more compelling areas of rosemary research.

Kidney Protection

Diabetic kidney disease is one of the most common and serious complications of long-standing diabetes. Two animal studies have found that rosemary offers some protection to the kidneys of diabetic rodents. In one, rosemary essential oil supplementation produced beneficial structural changes in the kidneys of diabetic rats, with the researchers concluding it had nephroprotective effects.¹² A more recent study found that a stabilized rosemary extract reduced kidney injury, improved glucose and lipid abnormalities, and decreased oxidative stress in mice with diabetic kidney disease.¹³

Wound Healing

People with diabetes often experience slow wound healing, which can lead to chronic ulcers and serious infections. Rosemary has shown promise here too, at least in animal models. In diabetic mice, topical application of rosemary extract to full-thickness skin wounds significantly reduced inflammation and accelerated wound closure, new blood vessel formation, and collagen deposition compared to untreated wounds.¹⁴ A more recent study used a rosemary oil nanoemulsion combined with quercetin and found it shifted the immune response in wounds from pro-inflammatory to pro-healing, accelerating closure in diabetic rats.¹⁵

These wound-healing findings are still preclinical, but they suggest rosemary’s benefits for people with diabetes could extend well beyond glucose numbers on a lab report.

How Rosemary Affects the Gut

There is growing recognition that the community of microbes living in the gut plays a role in metabolic health, including blood sugar regulation. A study in rats found that a rosemary extract rich in carnosic acid selectively changed the composition of gut bacteria and inhibited an enzyme involved in fiber digestion. In obese rats, the extract increased the production of short-chain fatty acids, which are metabolic byproducts of gut bacteria that have been linked to improved insulin sensitivity and reduced inflammation.¹⁶

Interestingly, the effect differed depending on body weight. Lean rats showed decreased short-chain fatty acid levels, while obese rats showed increased levels, suggesting the extract interacts differently with different metabolic states. This is a single animal study and far from actionable, but it hints at yet another channel through which rosemary might influence metabolic health.

Safety, Side Effects, and Drug Interactions

The safety profile of rosemary in culinary amounts is well established. People have been eating it for thousands of years. The question is whether concentrated extracts and supplements carry additional risks, and the answer is: potentially, yes.

A comprehensive toxicity review published in 2024 catalogued the known adverse effects observed in animal studies. At high doses, rosemary extracts have been associated with liver and kidney changes, including elevated markers of organ stress. Reproductive toxicity has also been observed, including reduced sperm production and testosterone levels in male animals. Genotoxic effects, including DNA fragmentation, have appeared at certain doses.¹⁷ These findings are from animal experiments using doses far beyond what you would get from cooking with rosemary, but they are relevant for anyone considering high-dose supplements.

On the reassuring side, a rigorous 13-week oral toxicity study of a rosemary concentrate containing ursolic acid in rats found no adverse effects at any dose tested, up to a very high 4,000 mg per kilogram of body weight per day. There were no deaths, no clinical signs, and no changes in organ weights, blood chemistry, or tissue histology during the dosing period or during a four-week recovery period after dosing stopped.¹⁸

The apparent contradiction between these two bodies of evidence likely reflects differences in extract composition, concentration, and study design. Crude whole-plant extracts contain different proportions of active compounds than standardized concentrates, and the dose makes the poison in almost every case. For practical purposes, reasonable conclusions look like this:

Culinary use: Virtually no risk. Sprinkling rosemary on your food, drinking rosemary tea, or using dried rosemary in recipes is safe for the vast majority of people.
Supplemental extracts: Likely safe at moderate doses, but the lack of standardization across commercial products makes it hard to know exactly what you are getting. Start low if you decide to try one.
High-dose supplements: Warrant caution, especially for pregnant women, people with liver or kidney disease, and men concerned about fertility.

A concern specific to people with diabetes is the potential for rosemary to interact with blood-sugar-lowering medications. If rosemary genuinely lowers blood glucose, combining it with insulin or oral diabetes drugs could theoretically push blood sugar too low. The human study that found a 16 to 23% drop in fasting glucose when rosemary was added to existing medications illustrates this risk: those are clinically significant reductions, not trivial ones.⁷ If you take diabetes medication and plan to add a rosemary supplement, talk to your doctor and monitor your blood sugar more frequently during the transition.

Culinary Rosemary Versus Supplements

One of the most common questions people have is whether cooking with rosemary “counts.” The short answer is that culinary rosemary provides some of the relevant compounds, but the concentrations are much lower than those used in most studies. Many of the animal experiments used standardized extracts at doses that would translate to consuming unreasonable quantities of fresh or dried rosemary leaves.

That said, the lipid-profile study mentioned earlier used rosemary leaf powder rather than a concentrated extract, and participants consuming 10 grams daily saw meaningful changes in cholesterol markers.⁹ Ten grams is roughly two heaping teaspoons of dried rosemary per day, which is a lot to eat but not impossible if you spread it across meals. It suggests that generous dietary use of rosemary might produce at least modest metabolic benefits, even without a supplement.

For those considering a supplement, there is no consensus on the ideal formulation. Some products are standardized to carnosic acid content, others to rosmarinic acid, and many do not specify. The research base is too thin to recommend one formulation over another. What the science does suggest is that extracts containing a broad spectrum of rosemary’s phenolic compounds, rather than isolates of a single compound, tend to perform well in experiments, which aligns with the general principle that whole-plant extracts often outperform single-molecule fractions.

The Vitamin B12 Connection

One underappreciated finding from the human study of rosemary in diabetic patients is the B12 boost. Metformin, one of the world’s most widely prescribed diabetes drugs, is well known to reduce vitamin B12 levels over time. B12 deficiency can cause nerve damage, fatigue, and cognitive problems, symptoms that are sometimes mistaken for diabetic neuropathy. In the study, patients taking both metformin and another diabetes drug saw their B12 levels increase by about 10% after adding rosemary, while those on a single drug saw a 25% increase.⁷

This is just one study, and the mechanism behind the B12 effect is not clear. But if it holds up, it would represent a genuinely valuable ancillary benefit for the millions of people on long-term metformin. It is the kind of finding that deserves a targeted follow-up trial, though it is unclear whether one has been conducted.

Where the Research Stands and What Is Missing

The pattern across rosemary-and-diabetes research is consistent: strong and reproducible results in cells and animals, a plausible and well-mapped set of mechanisms, and a thin but suggestive handful of human studies. This is a stage of evidence that many dietary compounds never reach. Plenty of herbs that were once promoted for blood sugar management turned out to do nothing meaningful in clinical trials. Rosemary has not yet had that reckoning, for better or worse, because the large trials have not been done.

What is specifically missing includes randomized, placebo-controlled trials large enough to detect clinically meaningful effects, dose-finding studies to identify optimal intake levels, long-term safety data in humans, and studies in diverse populations. Almost everything known about rosemary’s blood-sugar effects comes from the Mediterranean region or the Middle East, and metabolic responses to dietary interventions can vary across ethnic and genetic backgrounds. Until that evidence gap closes, the most responsible framing is that rosemary is a promising dietary addition with legitimate biological activity, not a treatment that anyone should rely on as a primary strategy for managing diabetes.

1
PubMed Central. Rosemary Extract as a Potential Anti-Hyperglycemic Agent: Current Evidence and Future Perspectives
2
Current Opinion in Food Science. Preventive and protective properties of rosemary (Rosmarinus officinalis L.) in obesity and diabetes mellitus of metabolic disorders: a brief review
3
PubMed. Bioaccessibility and inhibitory effects on digestive enzymes of carnosic acid in sage and rosemary
4
PubMed. Increased skeletal muscle glucose uptake by rosemary extract through AMPK activation
5
PubMed. The mechanisms of carnosic acid attenuates tumor necrosis factor-α-mediated inflammation and insulin resistance in 3T3-L1 adipocytes
6
PubMed. Rosmarinic acid modulates the antioxidant status and protects pancreatic tissues from glucolipotoxicity mediated oxidative stress in high-fat diet: streptozotocin-induced diabetic rats
7
National Journal of Physiology Pharmacy and Pharmacology. Effect of rosemary on fasting blood glucose, hemoglobin A1c and Vitamin B12 in healthy person and Type 2 diabetic patients taking glucomid or/and metformin
8
PubMed Central. Recent updates on antidiabetic and antiobesity potential of carnosic acid
9
International Journal of Clinical Medicine. The Effects of Rosemary (Rosmarinus officinalis) Leaves Powder on Glucose Level, Lipid Profile and Lipid Perodoxation
10
PubMed. Effect of rosmarinic acid and carnosic acid on AGEs formation in vitro
11
Journal of Agricultural and Food Chemistry. Low-Density Lipoprotein, Collagen, and Thrombin Models Reveal that Rosmarinus officinalis L. Exhibits Potent Antiglycative Effects
12
PubMed Central. Assessment of Effects of Rosemary Essential Oil on the Kidney Pathology of Diabetic Adult Male Albino Rats
13
PubMed Central. A stabilized enrichment method for rosemary diterpenoids and their therapeutic potential in diabetic kidney disease
14
PubMed. Healing potential of Rosmarinus officinalis L. on full-thickness excision cutaneous wounds in alloxan-induced-diabetic BALB/c mice
15
Advanced Therapeutics. Accelerating Diabetic Wound Healing by Modulating the Inflammatory Environment Using Quercetin–Rosemary Oil Lipid Nanoemulsions with Artificial Intelligence‐Based Wound Closure Analysis
16
PLOS ONE. A Rosemary Extract Rich in Carnosic Acid Selectively Modulates Caecum Microbiota and Inhibits β-Glucosidase Activity, Altering Fiber and Short Chain Fatty Acids Fecal Excretion in Lean and Obese Female Rats
17
PubMed. Toxicity and safety of rosemary (Rosmarinus officinalis): a comprehensive review
18
PubMed. A 13-week repeated oral dose toxicity evaluation and a 4-week recovery evaluation of rosemary concentrate containing 50% ursolic acid in male and female rats