Diabetes mellitus (DM) is an endocrine disorder affecting more than 100 million
people worldwide. It is exemplified by hyperglycemia caused by imperfect functioning of
insulin, abnormal insulin secretion or sometimes the combination of both. The long-term
persistence of high glucose concentrations in the blood leads to the generation of abnormally
high level of free radicals and reactive oxygen species (ROS), change of various oxidative
stress biomarker levels, simultaneous decline of antioxidant defense mechanisms and thereby
causes a variety of diabetic complications in the body. Increasing evidence in both
experimental and clinical studies suggests that oxidative stress plays a major role in the
pathogenesis of both types of diabetes mellitus. Abnormally increased production of free
radicals and the simultaneous decline of antioxidant defense mechanisms can lead to damage
of cellular organelles and enzymes, enhanced lipid peroxidation, and development of insulin
resistance, creating complicacies. Changes in oxidative stress biomarkers and their
consequences are discussed in this chapter. In vivo studies of the effects of various
conventional and alternative drugs on these biomarkers are surveyed. There is a need to
continue to explore the relationship between free radicals, diabetes, and its complications, and
to elucidate the mechanisms by which increased oxidative stress accelerates the development
of diabetic complications, in an effort to expand treatment options. Many ethnobotanically
important herbal plants possessing antihyperglycemic potential are known to exist in nature.
Moreover, a large number of polyherbal formulations (PHFs) derived from these plants are
presently being prescribed as medicinal/dietary supplements for the management of DM. It
has become very much essential to explore the hidden active principles present in the
traditionally used antidiabetic herbal plants in order to standardize the formulations of various
herbal drugs for the betterment of both types of DM treatment. This chapter would well
indicate about how oxidative stress is involved in the pathogenesis of diabetes and its
complications. The experimental validations and biochemical aspects of traditionally used
antidiabetic plants in phytotherapy of DM are discussed to understand and elucidate the
antidiabetic as well as associated antioxidative potentials.
Keywords: Diabetes mellitus, oxidative stress, antioxidant, medicinal plant.
