Research Article EffectsofFermented Houttuynia cordata Thunb.onDiabeticRats Induced by a High-Fat Diet with Streptozotocin and on Insulin Resistance in 3T3-L1 Adipocytes Wannachai Sakuludomkan , 1 Ranchana Yeewa , 1 Subhawat Subhawa , 1 Chakkrit Khanaree, 2 Arisa Imsumran Bonness , 1 and Teera Chewonarin 1 1 Department of Biochemistry, Faculty of Medicine, Chiang Mai University, 110 Intravaroros Road, Sripoom, Muang, Chiang Mai 50200, ailand 2 e School of Traditional and Alternative Medicine, Chiang Rai Rajabhat University, 80 Phaholyothin Road, Ban Du, Muang, Chiang Rai 57100, ailand Correspondence should be addressed to Teera Chewonarin; teera.c@cmu.ac.th Received 23 April 2021; Accepted 26 July 2021; Published 6 August 2021 Academic Editor: C. S. Johnston Copyright © 2021 Wannachai Sakuludomkan et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Houttuynia cordata unb. (plukaow in ai language) exhibits several biological properties, and many products of H. cordata are therefore commercially available for human consumption, such as fermented juice or tablets as food supplements. is study aimed to investigate the antidiabetic effects of fermented H. cordata (HC) in high-fat diets and streptozotocin-induced diabetic rats. Oral administration of HC at a dose of 100 mg/kg.bw not only maintained bodyweight, food intake, and water consumption but also reduced blood glucose levels and improved glucose tolerance ability in the diabetic rats. Moreover, HC also decreased oxidative stress markers in serum and inflammatory-related mediators in pancreas tissues, indicating the improvement of pancreatic beta-cell function in the diabetic rats. In order to clarify the mechanism of HC, the effects of ethanolic extract of HC (HCE) on insulin resistance were determined in 3T3-L1 adipocytes. FHE could recover glucose uptake and decrease lipolysis in palmitate-treated 3T3-L1 adipocytes. Taken together, these results demonstrate that HC can improve diabetic symptoms by enhancing insulin sensitivity, reducing oxidative stress, and suppressing inflammation. 1. Introduction Type 2 diabetes mellitus is dramatically increasing world- wide and causes morbidity and mortality, as well as eco- nomic burdens on countries [1]. Epidemiologic studies have demonstrated the relationship between an increased inci- dence of type 2 diabetes and obesity-associated insulin re- sistance [2]. High accumulation of fat in adipose tissue plays an important role in chronic low-grade inflammation, leading to an increase in proinflammatory cytokine pro- duction [3]. ese proinflammatory cytokines can also re- duce insulin sensitivity in adipocytes, which cause the release of free fatty acids into the bloodstream [4–6]. Consequently, free fatty acids, especially palmitate, can induce muscle cells and liver cells to become insulin resistant, resulting in hy- perglycemia [7, 8]. e goal of treating diabetes as a medical condition is to reduce blood glucose levels, which can prevent or delay the occurrence of complications relating to the disease [9]. Nevertheless, common types of oral medi- cation used for the treatment of diabetes have demonstrated side effects and caused adverse reactions [10]. Currently, many herbal medicines have been recommended for the prevention and treatment of diabetes, in addition to con- ventional medication [11]. Houttuynia cordata unb., commonly known in ai as plukaow, is a natural herb indigenous to local areas of Northern ailand that is used in cooking in the region. It has been recognized in folk medicine for being used to Hindawi Journal of Nutrition and Metabolism Volume 2021, Article ID 6936025, 15 pages https://doi.org/10.1155/2021/6936025