A 43-year-old man from Hanoi discovered he had diabetes during a routine health checkup. Despite adjusting his diet, his fasting blood glucose level remained at 8.1 mmol/l.
Worried about having to use medication for a long time, he turned to online diabetes groups on social media to learn from their experiences. Many posts claimed that simply boiling about 20 guava leaves and drinking the decoction daily could lower blood sugar, even eliminating the need for medication.
Believing in what was claimed to be a "natural" method, this person ignored the doctor's treatment instructions and drank guava leaf tea daily instead of plain water.
Three months later, the man experienced frequent fatigue, thirst, and rapid weight loss. Initially, he attributed the weight loss to the positive effects of the guava leaves. Only after being encouraged by his family to go to the hospital for a check-up did he learn that his condition had worsened.
Test results showed his fasting blood glucose had increased to over 11 mmol/l, nearly double his previous level. In addition, he developed retinal damage, hypertension, and several other health problems related to diabetes.
Guava leaves should only be considered as a supplementary food in a healthy diet. (Illustrative image)
According to Dr. Duong Minh Tuan, Department of Endocrinology and Diabetes, Bach Mai Hospital, this is not an isolated case. Many newly diagnosed diabetes patients also choose traditional remedies such as guava leaves, mango leaves, or other herbs in the hope of curing the disease without medication.
From a modern pharmacological perspective, guava leaves contain many flavonoid compounds, including quercetin. This active ingredient can inhibit the α-glucosidase enzyme, helping to slow down carbohydrate absorption and support post-meal blood sugar reduction.
Several small-scale studies have also noted that guava leaf tea may improve blood glucose levels and HbA1c in people with prediabetes. In Japan , some guava leaf tea products are marketed as dietary supplements to help control blood sugar.
However, according to doctors, the available evidence is insufficient to confirm that guava leaves are a treatment for diabetes. Most studies are small-scale, have short follow-up periods, and have not standardized the content of active ingredients, so they cannot replace established treatment protocols.
In particular, for people with type 1 diabetes, arbitrarily stopping insulin and using guava leaves instead poses serious risks. This is a group of diseases where the body is almost incapable of producing insulin. Without adequate insulin injections, patients may experience ketoacidosis, coma, and even life-threatening conditions.
According to Dr. Tuan, guava leaves should only be considered a supplementary food in a healthy diet. To effectively control the disease, people with diabetes still need to maintain a proper diet, exercise regularly, monitor their blood sugar periodically, and use medication as prescribed.
"Diabetes is a chronic disease that requires long-term management using proven effective methods. Patients can use additional supportive products if needed, but should discuss this with their doctor before use to avoid unnecessary risks," Dr. Tuan advised.