Objective To determine the levels of some selected heavy metals in both the selected anti-diabetic herbal plants and infused concoctions for diabetes treatment. Methods Ten anti-diabetic plant samples: pawpaw leaves (Carica papaya), bitter melon leaves (Momordica charantia), holy basil leaves (Ocimum sanctum), bitter leaf (Vernonia amygdalina), ginger rhizome (Zingiber officinale), garlic (Allium sativum), African red pepper fruits (Capsicum frutescens), negro pepper grain (Xylopia aethiopica), cashew leaves (Anacardium occidentale) and onion bulb (Allium cepa) were evaluated for heavy metals. These were digested using standard methods and analyzed for manganese, copper, nickel, chromium, zinc, cadmium and lead using atomic absorption spectrophotometer. The infused concoctions (I and II) prepared from these medicinal herbs administered to diabetic patients were also analyzed for these heavy metals. Concoction I contained all the plants and honey with the exception of Momordica charantia and Ocimum sanctum which constituted concoction II with water only. The data obtained were subject to descriptive (mean and standard deviation) and inferential (ANOVA and DMRT) statistics. Results Chromium and nickel levels were below detection limits in concoction I while manganese [(0.11 ± 0.01) μg/g] and zinc [(0.09 ± 0.01) μg/g] were detected in concoction II. Honey contained manganese [(0.10 ± 0.01) μg/g] and nickel [(0.70 ± 0.01) μg/g]. The anti-diabetic medicinal herbs and infused concoctions (I and II) were observed to contain heavy metals below the compared limits. Conclusions The study thus shows that the herbs and concoctions are safe from the heavy metals considered. However, right dosage of the anti-diabetic concoctions should always be considered to prevent possible chronic side effects from bio-accumulation of heavy metals.