Man nearly loses sight after replacing diabetes medication with guava leaf water

A 43-year-old man, diagnosed with diabetes, opted for a daily brew of 20 guava leaves instead of prescribed treatment, leading to a doubling of his blood sugar and the onset of several dangerous underlying conditions.

Doctor Duong Minh Tuan, from the Endocrinology and Diabetes Department at Bach Mai Hospital, reported on a patient who was diagnosed with diabetes during a routine check-up, with a fasting blood sugar level of 8,1 mmol/l. Instead of adhering to the prescribed medication, the patient independently altered his diet and followed advice from social media groups, brewing guava leaves to drink daily in place of water, believing it would lower his blood sugar.

After three months, the patient experienced rapid weight loss, persistent fatigue, and constant thirst. Hospital test results revealed his blood sugar level exceeded 11 mmol/l, which is double the normal range. In addition to the soaring blood sugar, he also developed high blood pressure and suffered complications, including damage to the retina (fundus).

Doctor Tuan noted this common scenario: many newly diagnosed diabetes patients often reject conventional medical treatment. Instead, they trust unverified word-of-mouth remedies, such as guava or mango leaves, or herbal concoctions of unknown origin, hoping for a complete cure.

Scientifically, guava leaves contain flavonoids, particularly quercetin, which can inhibit the α-glucosidase enzyme. This action helps slow carbohydrate absorption and reduce post-meal blood sugar levels. Some small-scale studies conducted in Japan have indicated that guava leaf tea might improve HbA1c levels in pre-diabetic individuals. Despite these findings, the current evidence is not robust enough to assert that guava leaves can serve as a substitute for prescribed medication. Most studies suffer from small sample sizes, short observation periods, and a lack of standardization regarding the necessary active compound content.

Experts warn that replacing prescribed treatment with herbal remedies carries substantial risks, particularly for individuals with type 1 diabetes who rely on insulin for survival. Insulin deficiency can lead to diabetic coma and become life-threatening. Doctors advise strict adherence to medication, coupled with a balanced diet and regular physical activity, to effectively manage the disease and prevent complications.