Background <p>Diabetes Mellitus is often a long-term health condition that continues to raise concerns regarding the burden upon an individual’s mental health, due to the commitment required for day-to-day self-care. People living with diabetes frequently use complementary medicine as part of their diabetes self-care to manage their mental health and this raises a number of significant risk management issues. Unfortunately, no research has explored the influence of lowered mental health functioning upon both the conventional and complementary medicine health service use amongst people living with diabetes.</p> Methods <p>An examination of the conventional and complementary medicine health service use amongst men and women living with diabetes and normative or lowered mental health functioning, was undertaken by completing a secondary analysis of the Complementary Medicine Use, Health Literacy and Disclosure study.</p> Results <p>Of the 176 participants reporting a diabetes diagnosis, 74% reported lowered mental health functioning, compared to 60% without a diabetes diagnosis. Compared to people living with diabetes and normative mental health functioning, those with lowered mental health functioning were 9 times more likely to consult with a Western herbalist (OR = 9.17, 95% CI: 1.097–76.84), twice as likely to use vitamins or minerals (OR = 2.34, 95% CI: 1.061–5.151), and 5 times more likely to engage in relaxation or meditation practice (OR = 5.10, 95% CI: 1.362–19.129).</p> Conclusion <p>People living with diabetes who have lowered mental health functioning appear even more likely to use complementary medicine than conventional medicine, than those with normative mental health functioning. This reinforces the need to resolve clinical governance issues associated with complementary medicine use, especially what role complementary medicine practitioners can fulfil as part of coordinated diabetes care teams, to support patient health and well-being.</p>