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Having too much glucose in the bloodstream, a condition known as hyperglycaemia, is increasingly linked to worsening infertility in men with diabetes. But researchers have suggested that medicinal plants traditionally used to treat diabetes and inflammation may offer a promising therapeutic approach.

A new review by scientists from the University of the Western Cape (UWC) and the Cape Peninsula University of Technology (CPUT) warned that as global diabetes rates continue to climb, cases of male infertility linked to hyperglycaemia-induced reproductive damage are also likely to rise.

The study, titled “The role of hyperglycaemia, oxidative stress, and inflammation in diabetes-related male infertility: Therapeutic properties of medicinal plants”, was published in a peer-reviewed Journal of Herbmed Pharmacology.

The research highlighted oxidative stress and inflammation as major drivers of declining sperm quality in men with diabetes. Oxidative stress occurs when the body’s immune system can not maintain a balance between disease-fighting antioxidants and unstable molecules known as “free radicals”.

When free radicals are in excess in the body, they damage DNA and cells, contributing to ageing and diseases including diabetes, cancer and heart disease. In the male reproductive system, excess free radicals trigger oxidative stress that weakens antioxidant defences and negatively affects sperm quality.

About 15% of couples globally experience infertility, with male factors accounting for more than 40% of cases, according to the World Health Organization (WHO). In South Africa, where diabetes affects about 2.3 million people, this issue is receiving attention as the country commemorates World Diabetes Day on November 14. It is the world's largest diabetes awareness campaign, reaching more than one-billion people across more than 160 countries. 

The 2025 theme, Diabetes and Well-being, specifically focuses on diabetes in the workplace, drawing attention to the challenges that people with diabetes face at work. In the latest study, which reviewed both animal models and some early human studies, Prof Chinyerum Opuwari, a senior lecturer in the Department of Medical Biosciences at UWC, and one of the study’s researchers, argued that current diabetes treatments predominantly focus on lowering blood sugar levels. They overlook other harmful processes that contribute to serious complications, including male reproductive damage. She collaborated with CPUT researchers Dr Murendeni Nethengwe, Dr Kunle Okaiyeto, and Prof Oluwafemi Oguntibeju.

The research team suggested that targeting inflammation and oxidative stress may be equally important in protecting patient health, and that traditional medicinal plants used for centuries across South Africa, Nigeria, China and India could play a key role in treating diabetes-related male infertility.

Several plants, such as Cleome rutidosperma (fringed spiderflower, native to tropical parts of Africa), Alpinia officinarum (Chinese ginger), Retama raetam (white weeping broom, that grows in the Mediterranean region), red onion extracts, and Turnera diffusa (a Mexican shrub), have all shown strong antioxidant and anti-inflammatory activity, while improving sperm quality. In some studies, raw cinnamon and date seeds improved glucose control and antioxidant status in people with Type 2 diabetes to such an extent that they outperformed standard antidiabetic drugs like metformin.

The researchers suggested these medicinal compounds could offer affordable complementary treatment for diabetes, which remains expensive for many, and emphasised that further studies are needed to fully understand how they work.

Prof Opuwari explained that given South Africa’s extraordinary plant biodiversity, comprising about 10% of the world’s flora, this underutilised resource is critical for addressing the nation’s most pressing health challenges, such as HIV/AIDS, tuberculosis, diabetes and cardiovascular disease, which currently overwhelm the underfunded public healthcare system.

“With 60-80% of South Africans, particularly those in rural communities, relying on traditional medicinal plants as their primary healthcare resource due to limited access to Western medical facilities, there is an urgent need to scientifically validate these indigenous practices,” she said.

Beyond addressing immediate health needs, Prof Opuwari said scientific documentation of traditional medicinal knowledge serves the dual purpose of preserving irreplaceable indigenous heritage that is rapidly eroding with urbanisation.

“By establishing an evidence base for traditional plant medicines, this research can inform health policy, facilitate the integration of traditional and Western medical practices, and ultimately contribute to more sustainable, and culturally appropriate healthcare solutions tailored to South Africa's unique socioeconomic and epidemiological landscape,” she said.