Research shows that Lactobacillus rhamnosus GG, a probiotic bacteria, improved reproductive health in diabetic rats by restoring sperm quality, increasing testosterone levels, and reducing testicular damage. According to Gram Research analysis of this 2026 study, both live and inactive forms of the bacteria provided benefits, suggesting probiotics might help protect male fertility in type 1 diabetes, though human studies are still needed to confirm these findings.
A new study from 2026 shows that a specific type of helpful bacteria called Lactobacillus rhamnosus GG (LGG) may protect the reproductive health of male rats with type 1 diabetes. According to Gram Research analysis, when researchers gave diabetic rats either live or inactive forms of this bacteria, it improved sperm quality, testosterone levels, and reduced damage to testicular tissue. The bacteria appears to work by changing how genes are turned on and off in reproductive cells. While this research was done in rats, it suggests that probiotics might become a helpful dietary supplement for men with diabetes who are concerned about fertility.
Key Statistics
A 2026 research article published in Scientific Reports found that Lactobacillus rhamnosus GG improved sperm motility and increased testosterone levels in rats with type 1 diabetes compared to untreated diabetic rats.
The study demonstrated that both live probiotic and inactive paraprobiotic forms of Lactobacillus rhamnosus GG reduced testicular damage and oxidative stress in diabetic rats, suggesting the bacteria doesn’t need to be alive to provide protective benefits.
Diabetic rats treated with Lactobacillus rhamnosus GG showed improved DNA methylation patterns in testicular cells, with restored expression of proteins that control gene activity, indicating a molecular mechanism for the bacteria’s protective effects.
The Quick Take
- What they studied: Whether a probiotic bacteria called Lactobacillus rhamnosus GG could protect male reproductive health and fertility in rats with type 1 diabetes
- Who participated: Laboratory rats divided into 9 groups: healthy control rats, rats with induced diabetes, and diabetic rats treated with either live or inactive forms of the bacteria, given either before or after diabetes developed
- Key finding: Both live and inactive forms of the bacteria improved sperm movement, increased testosterone levels, and reduced testicular damage in diabetic rats compared to untreated diabetic rats
- What it means for you: This research suggests probiotics might help protect male fertility in people with type 1 diabetes, though human studies are needed to confirm these findings. Men with diabetes interested in fertility should discuss probiotic supplements with their doctor.
The Research Details
Researchers created type 1 diabetes in laboratory rats using a chemical called streptozotocin. They then divided the diabetic rats into different groups: some received live Lactobacillus rhamnosus GG bacteria, some received inactive (dead) bacteria, and some received no treatment. Some groups received the bacteria before diabetes developed (preventive), while others received it after (therapeutic). The researchers measured multiple outcomes including blood sugar levels, sperm quality, testosterone levels, and examined testicular tissue under a microscope.
The study also looked at molecular changes in the rats’ reproductive cells, specifically how DNA methylation (a process that controls which genes are active) was affected by diabetes and by the bacterial treatment. This involved measuring special proteins called DNMTs that control DNA methylation patterns.
This approach allowed researchers to understand not just whether the bacteria helped, but also the biological mechanisms explaining how it might work. The use of both live and inactive bacteria was important because it helped determine whether the bacteria needed to be alive to provide benefits.
Understanding how gut bacteria affects male reproductive health in diabetes is important because type 1 diabetes commonly causes fertility problems in men, and current treatments are limited. By studying the molecular mechanisms (DNA methylation changes), this research provides insight into how probiotics might work at a cellular level, which could lead to better treatments.
This study was published in Scientific Reports, a peer-reviewed journal with good scientific standards. The researchers used multiple measurement methods to evaluate outcomes, which strengthens confidence in the findings. However, this is animal research, so results may not directly apply to humans. The specific sample size wasn’t provided in the abstract, but the study appears to have used adequate numbers of animals in each group based on the detailed analysis described.
What the Results Show
In diabetic rats that received no treatment, blood sugar levels were very high, testicular tissue showed damage, sperm movement decreased significantly, and testosterone levels dropped. When researchers gave these diabetic rats the probiotic bacteria (either live or inactive), blood sugar levels improved, testicular damage was reduced, sperm movement improved, and testosterone levels increased.
Interestingly, both the live bacteria and the inactive (dead) bacteria provided benefits, suggesting that the bacteria doesn’t need to be alive to help. This is important because inactive bacteria might be safer and easier to store than live bacteria.
The bacteria also affected DNA methylation patterns in testicular cells. Diabetes reduced the expression of certain proteins (DNMTs) that control DNA methylation, but the bacterial treatment helped restore these proteins to more normal levels. This molecular change appears to be one way the bacteria protects reproductive health.
The study found that diabetes increased cell death (apoptosis) in testicular tissue and increased oxidative stress (harmful chemical reactions). Both the live and inactive bacterial treatments reduced these harmful processes. Body weight and testis weight, which decreased in untreated diabetic rats, improved in rats receiving bacterial treatment. Whether the bacteria was given before diabetes developed (preventive) or after (therapeutic) both showed benefits, though the timing affected the magnitude of improvement.
This is described as the first study to examine how Lactobacillus rhamnosus GG specifically affects DNA methylation in testicular tissue of diabetic animals. Previous research has shown that gut bacteria affects overall health in diabetes and that probiotics can help with some diabetes complications, but the specific mechanism involving testicular DNA methylation is new. The findings align with growing evidence that the gut microbiome plays an important role in reproductive health.
This research was conducted in laboratory rats, not humans, so results may not directly apply to people with diabetes. The study didn’t measure whether the bacteria actually changed the composition of the rats’ gut microbiota, so we don’t know if the benefits came from the bacteria itself or from other effects it might have. The abstract doesn’t provide the exact number of rats in each group. Additionally, this was a relatively short-term study in animals, so we don’t know if benefits would persist long-term in humans or how long treatment would need to continue.
The Bottom Line
Based on this animal research, probiotics containing Lactobacillus rhamnosus GG show promise for protecting male reproductive health in type 1 diabetes. However, human clinical trials are needed before making specific recommendations. Men with type 1 diabetes who are concerned about fertility should discuss probiotic supplements with their endocrinologist or urologist, as this research is preliminary. Confidence level: Low to Moderate (animal study only).
Men with type 1 diabetes, particularly those concerned about fertility or reproductive health, should be aware of this research. Healthcare providers treating diabetic men should consider discussing probiotics as a potential complementary approach. This research is less relevant for people with type 2 diabetes or those without diabetes, though some benefits might apply more broadly.
In the rat study, improvements in sperm quality and testosterone appeared within the timeframe of the experiment (specific duration not stated in abstract). In humans, if probiotics prove effective, benefits would likely take weeks to months to appear, as changes to gut bacteria composition and gene expression typically occur gradually.
Frequently Asked Questions
Can probiotics help with fertility problems caused by diabetes?
A 2026 study found that Lactobacillus rhamnosus GG improved sperm quality and testosterone in diabetic rats, suggesting probiotics might help. However, this was animal research only—human studies are needed before recommending probiotics for diabetes-related fertility issues. Consult your doctor before starting supplements.
Does the probiotic bacteria need to be alive to work?
Interestingly, the study found that both live and inactive forms of Lactobacillus rhamnosus GG provided similar benefits in diabetic rats. This suggests the bacteria doesn’t need to be alive to help protect reproductive health, which could make supplements easier to store and use.
How does gut bacteria affect male fertility in diabetes?
This study shows that Lactobacillus rhamnosus GG affects DNA methylation—a process controlling which genes are active in reproductive cells. Diabetes disrupts this process, but the bacteria appears to restore normal gene regulation patterns, protecting testicular tissue and sperm quality.
Should men with type 1 diabetes take probiotic supplements?
While this research is promising, it’s from animal studies only. Men with type 1 diabetes interested in probiotics should discuss options with their endocrinologist or urologist. They can help determine if supplements are appropriate and monitor for any interactions with diabetes medications.
How long would it take to see benefits from probiotics?
The rat study showed improvements within the experimental timeframe, but human timelines are unknown. If probiotics prove effective in people, benefits would likely take weeks to months as gut bacteria composition and gene expression change gradually. Consistency is important.
Want to Apply This Research?
- Users with type 1 diabetes could track probiotic supplement intake (brand, dose, frequency) alongside monthly testosterone levels (if available through testing) and fertility markers like semen analysis results if pursuing fertility evaluation.
- If a user’s doctor recommends Lactobacillus rhamnosus GG supplementation, the app could send daily reminders to take the supplement at the same time each day, track consistency, and log any changes in energy levels, blood sugar control, or other health markers the user wants to monitor.
- Establish a baseline of current health markers (blood sugar control, energy levels, general wellness), take the probiotic consistently for 8-12 weeks, then reassess the same markers. Track any changes in diabetes management, overall health, or fertility-related concerns. Share results with healthcare provider to determine if continuation is beneficial.
This research was conducted in laboratory rats and has not been tested in humans. The findings are preliminary and should not be considered medical advice. Men with type 1 diabetes should not start probiotic supplements without consulting their healthcare provider, as probiotics may interact with diabetes medications or other treatments. This article is for educational purposes only and does not replace professional medical diagnosis, treatment, or advice. Always consult with a qualified healthcare provider before making changes to your diabetes management or starting new supplements.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.