Effect of Herbal Tea Consumption on Blood Sugar Levels: A Review of Current Evidence

Diabetes mellitus, particularly type 2 diabetes mellitus (T2DM), has become a major public health concern worldwide. Along with medicines, healthy eating, regular physical activity, and weight management, there is growing interest in simple dietary approaches that may help improve blood glucose control. Herbal teas are one such approach. They have been used traditionally for centuries and are now increasingly studied for their possible effects on blood sugar, insulin sensitivity, inflammation, and oxidative stress. Unlike green or black tea, which are prepared from Camellia sinensis, herbal teas are made from different plant parts, including leaves, flowers, roots, seeds, and bark. Common examples include chamomile, cinnamon, fenugreek, and ginger. This review examines the available scientific evidence regarding the effect of herbal tea consumption on blood glucose levels, with particular emphasis on type 2 diabetes. Recent clinical evidence suggests that some herbal teas may have beneficial effects on fasting blood glucose and glycated haemoglobin (HbA1c). A recent systematic review and meta-analysis of 14 randomised controlled trials involving 551 people with T2DM reported significant reductions in fasting blood glucose and HbA1c following consumption of non-Camellia sinensis herbal teas (Zarasvand et al., 2025). Chamomile tea has shown promising effects on HbA1c and insulin resistance, while fenugreek and cinnamon have also demonstrated potential benefits. Evidence for ginger, however, remains inconsistent. The possible mechanisms include delayed carbohydrate digestion and absorption, improved insulin sensitivity, antioxidant activity, and reduction of inflammation. Despite these encouraging findings, differences in herbal species, dosage, preparation, duration of intervention, and participant characteristics make it difficult to draw firm conclusions. Herbal tea should therefore be considered a complementary dietary option rather than a replacement for prescribed diabetes treatment. Further well-designed clinical trials are needed to determine the long-term effectiveness and appropriate dosage of different herbal teas.