Raspberry leaf tea may offer a natural way to help manage blood sugar levels, according to a new study.
The research, published in Nutrients, found that drinking the tea after consuming sucrose led to lower blood glucose levels in healthy adults compared to consuming sucrose alone. Sucrose, commonly known as table sugar, is found in processed foods like baked goods and soda and naturally occurs in some fruits and vegetables.
These findings come as nearly half of U.S. adults have been diagnosed with either prediabetes or diabetes, according to the Centers for Disease Control and Prevention.
The research included few participants, and “longer-term studies in individuals at risk for type 2 diabetes are needed to confirm clinical relevance,” said study author Hind Mesfer S. Alkhudaydi, a PhD candidate at the University of Reading in the United Kingdom and lecturer at Taif University in Saudi Arabia.
Still, the findings hint that raspberry leaf tea may support glucose control as a gentle, accessible complement to medication or other standard treatments.
“In our trial, raspberry leaf tea was well tolerated and did not cause gastrointestinal side effects,” Hind noted.
Raspberry leaf tea is made from the red raspberry plant (Rubus idaeus), the same one that produces the berries.
The leaves are rich in plant compounds called polyphenols, which have antioxidant and anti-inflammatory properties. They have a long history in herbal medicine, particularly for supporting menstruation and pregnancy, said Amna Haq, MS, RD, LDN, a dietitian specializing in metabolic disorders and owner of The Inclusive Dietitian in Chicago.
While many modern studies have looked at the health effects of raspberries, far fewer have focused on the leaves. According to Hind, there “were virtually no clinical studies” investigating how raspberry leaves might influence blood glucose control. She and her colleagues wanted to change that.
“We were motivated by this research gap and by the presence of promising polyphenols in raspberry leaves that might influence glycemic regulation,” she said.
Researchers recruited 22 adults aged 18 to 65 with no history of prediabetes, diabetes, or insulin resistance. Across four separate sessions, participants consumed either 50 grams of sucrose or glucose—another type of sugar found in foods like grapes, corn, potatoes, and energy drinks—with or without 10 grams of raspberry leaf tea.
About two hours after consumption, everyone had their blood glucose and insulin levels checked.
After analysis, researchers discovered that when people drank raspberry leaf tea after consuming sucrose, their blood glucose and insulin levels were significantly reduced. Blood sugar levels dropped by 26% after 15 minutes and 44% after 30 minutes. Notably, when raspberry leaf tea was consumed alongside glucose, there was no significant drop in blood glucose and insulin levels.
The raspberry leaf tea used in the study was found to contain 37 polyphenolic compounds, including ellagitannins, flavonoids, and phenolic acids. “The effects found in study participants are likely due to these polyphenols,” Alkhudaydi explained. They are thought to slow the breakdown of sucrose, in turn reducing rapid spikes in blood sugar.
Before reaching for raspberry leaf tea to manage your blood sugar, experts recommend consulting a healthcare provider, especially if you’re pregnant or taking blood-sugar lowering medications.
It’s also worth keeping in mind that the study comes with some major caveats.
For one, it was small. Researchers tested only the acute—not long term—effects, and the participant pool included only healthy people. Plus, this is the first human study of its kind.
So while raspberry leaf tea could theoretically decrease blood sugar levels, it’s too soon to know for sure. In light of that, Jamie Baham, MS, RDN, LD, a diabetes-focused dietitian and owner of Ladybug Nutrition, told Health that drink is worth trying as part of a balanced diet and if you enjoy it, but not solely for the purpose of reducing blood sugar spikes.
Haq agreed. “I would recommend incorporating one cup of raspberry leaf tea (brewed with a few tablespoons of leaves) alongside a carbohydrate-rich meal—but more so for general enjoyment,” she said.
To more reliably manage blood sugar levels, Haq suggested eating meals with protein and focusing on fiber-rich foods, such as:
- Vegetables
- Legumes
- Nuts
- Seeds
- Whole grains
Also, steer clear of ultra-processed foods and added sugars as much as possible, she added.
