Does cordyceps lower blood sugar? In rats and mice, often yes. In people, the best trial we found says no. A 16-week randomised trial in adults with type 2 diabetes found that reishi with or without Cordyceps sinensis had no effect on HbA1c or fasting glucose. That gap between animal and human results is the honest headline. What it means in practice is this: don't use cordyceps to manage blood sugar, and if you take diabetes medicine, treat cordyceps as something that might still nudge your levels.
Animal studies report that cordyceps lowers blood glucose, but many used injected compounds or chemically induced diabetes. In the strongest human trial, 3 g a day of reishi with or without Cordyceps sinensis for 16 weeks had no effect on HbA1c or fasting glucose in 84 people with type 2 diabetes (Klupp 2016). An 8-week training trial with a Rhodiola and cordyceps supplement found no added change in fasting glucose or insulin (Liao 2019). Cordyceps isn't a diabetes treatment. If you take glucose-lowering medicine, check with your doctor and monitor your levels.
This article focuses on blood sugar. For cordyceps safety in general, see our guide to cordyceps side effects and interactions, and for amounts, our cordyceps dosage guide.
What Does the Animal Research Show?
Mostly lower blood sugar, under very specific conditions. Here are typical examples:
- In rats made diabetic with streptozotocin and nicotinamide, Cordyceps fruiting body lowered blood glucose (Lo 2004). A later study found similar effects for natural and fermented Cordyceps sinensis (Lo 2006).
- Water extracts of Cordyceps militaris lowered plasma glucose in diabetic rats, apparently through the nervous system (Cheng 2013).
- Cordycepin, a compound from Cordyceps militaris, reduced blood glucose by 47% in mice with chemically induced diabetes (Ma 2015).
These results are consistent, which is why the claim is so common. But read the methods. The diabetes was created with toxic chemicals that destroy insulin-producing cells. In the cordycepin study, the compound was injected into the abdomen, not swallowed, at doses up to 72 mg per kg of body weight. None of that resembles a person with type 2 diabetes taking a capsule.
What Do Human Trials Show?
Very little effect on blood sugar. We found no well-run human trial of cordyceps alone with blood sugar as the main outcome. The closest evidence comes from two trials of combinations.
Klupp 2016: reishi with or without cordyceps
An Australian team randomised 84 adults with type 2 diabetes and metabolic syndrome to reishi (Ganoderma lucidum), reishi plus Cordyceps sinensis, or placebo. The dose was 3 g a day for 16 weeks. The main outcomes were HbA1c, which reflects average blood sugar over about three months, and fasting plasma glucose.
The mushroom groups showed no effect on either. The baseline-adjusted difference in HbA1c was 0.13 percentage points, and in fasting glucose 0.03 mmol/L, both far from significant. There was no effect on secondary outcomes like blood pressure or cholesterol either (Klupp 2016).
Liao 2019: cordyceps with endurance training
A small Taiwanese study gave adults a Rhodiola and cordyceps supplement or placebo during eight weeks of endurance training. Training itself improved fasting glucose, insulin and insulin resistance. The supplement added nothing on these measures, although it did slightly improve body composition (Liao 2019).
Neither study is perfect. Both used combinations, and the Klupp trial pooled its two mushroom groups. But they're the best randomised human data available, and neither found a blood sugar effect.
Why Don't the Animal Results Carry Over to People?
There are several reasons, and they apply to most mushroom research, not just cordyceps.
- The disease model is different. Streptozotocin and alloxan destroy the pancreas's insulin-making cells, which looks more like type 1 diabetes. Most people with diabetes have type 2, driven by insulin resistance.
- The dose is different. Animal studies often use doses per kilogram that would mean many grams a day for an adult.
- The route is different. Some studies inject purified compounds. Swallowed capsules have to survive digestion and absorption first.
- The product is different. A study extract may be standardised and concentrated. A shop supplement varies by species, strain, growing method and extraction.
So when you read "cordyceps lowers blood sugar", ask: in what animal, with what disease model, at what dose, given how? The answer usually explains why human trials don't find the same thing.
That doesn't make the animal work worthless. It tells researchers where to look. It just isn't enough to tell a person with diabetes what a capsule will do for them.
What Has Cordyceps Shown in People?
Its clearest human results are about exercise, not glucose. In older adults, 1 g a day of a Cs-4 cordyceps product for 12 weeks raised metabolic threshold by roughly 10%. In young adults, a blend containing Cordyceps militaris improved VO2max after three weeks. Those are modest fitness effects, and they're where cordyceps research is strongest. If you're choosing cordyceps, choose it for that reason, not for blood sugar.
What About the Chinese Kidney Studies?
You may see claims based on a large body of Chinese research. Products made from Cordyceps sinensis mycelium, such as Jinshuibao, are used in China alongside standard medicines for diabetic kidney disease.
A 2023 meta-analysis pooled 38 randomised trials with 3,167 patients that added Ophiocordyceps sinensis to standard blood pressure medicines (Yan 2023). These trials looked mainly at kidney markers like urine protein, not at blood sugar control, and none reported long-term outcomes such as kidney failure or heart events. Many were small and at risk of bias. They don't show that cordyceps lowers blood sugar, and they're about prescribed medical products, not shop supplements.
Is It Safe to Take Cordyceps With Diabetes Medicine?
Possibly, but be careful. Even though human trials haven't shown a meaningful effect, the animal data is consistent enough that an additive effect can't be ruled out in a particular person. The concern is low blood sugar, especially with insulin or sulfonylureas such as gliclazide.
If you take diabetes medicine and want to try cordyceps:
- Talk to your doctor or diabetes nurse first.
- Start at a low dose and add nothing else new at the same time.
- Check your glucose more often for the first few weeks.
- Know the signs of low blood sugar: shakiness, sweating, hunger, confusion, a fast heartbeat.
- Never reduce or stop prescribed medicine on your own.
The same caution applies to several other mushrooms. Reishi and maitake carry similar warnings. Our guide to mushroom supplements and medication interactions lists them together.
Can Cordyceps Help Prevent Diabetes?
There's no evidence that it can. No human study has tested cordyceps for preventing type 2 diabetes. The most reliable ways to lower risk are well known: regular physical activity, keeping a healthy weight, eating more fibre and less refined sugar, and sleeping well.
Exercise is worth singling out. In the Liao trial, the training itself improved fasting glucose and insulin sensitivity, while the supplement didn't. Cordyceps is mostly studied for exercise capacity, and if it helps you train more, that's where any real benefit would come from. Our article on cordyceps and endurance in human studies covers that evidence.
How Does Cordyceps Compare With Other Mushrooms for Blood Sugar?
| Mushroom | Animal studies | Human evidence on glucose |
|---|---|---|
| Cordyceps | Mostly lowering | No effect in the best combined trial |
| Reishi | Mostly lowering | No effect over 16 weeks (Klupp 2016) |
| Maitake | Mostly lowering | Case reports and small studies only |
| Chaga | Mostly lowering | No good human trials |
The pattern is the same across species: promising in animals, unconvincing or untested in people. Our articles on maitake and blood sugar and chaga, glucose and insulin look at those mushrooms in detail.
Frequently Asked Questions
Does cordyceps lower blood sugar in humans?
The best evidence says not meaningfully. In a 16-week trial in 84 adults with type 2 diabetes, reishi with or without Cordyceps sinensis had no effect on HbA1c or fasting glucose. Animal studies show lowering, but under conditions that don't match human use.
Can people with diabetes take cordyceps?
Some do, but talk to your doctor first, especially if you use insulin or sulfonylureas. Start low, monitor your glucose more often, and never change your prescribed medicine on your own.
Is Cordyceps militaris better than Cordyceps sinensis for blood sugar?
There's no human comparison. Both have animal studies showing lower glucose. Most supplements today use cultivated Cordyceps militaris, because wild Cordyceps sinensis is rare and very expensive.
Can cordyceps cause low blood sugar?
It hasn't been shown to in human trials. However, the theoretical risk is greatest when it's combined with glucose-lowering medicines. Know the warning signs and test your glucose if you feel shaky, sweaty or confused.
Should I take cordyceps before a meal to control a glucose spike?
There's no evidence that this works. No study has tested cordyceps for post-meal glucose in people. Fibre, protein, smaller portions and a short walk after eating are proven ways to blunt spikes.
Related Articles
- Cordyceps Side Effects and Interactions
- Cordyceps Dosage Guide
- Mushrooms and Diabetes
- Maitake and Blood Sugar
- Cordyceps and Reproductive Function in Diabetic Men
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- Liao YH, Chao YC, Sim BY, et al. Rhodiola/Cordyceps-based herbal supplement promotes endurance training-improved body composition but not oxidative stress and metabolic biomarkers: a preliminary randomized controlled study. Nutrients. 2019;11(10):2357. PubMed 31623349
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- Yan G, Chang T, Zhao Y, et al. The effects of Ophiocordyceps sinensis combined with ACEI/ARB on diabetic kidney disease: a systematic review and meta-analysis. Phytomedicine. 2023;108:154531. PubMed 36375237