2. The pathophysiology and etiology of type 2 diabetes mellitus

1. Introduction

of Qigong in the management of T2DM [4, 5].

emerged as a global health crisis.

Qigong (pronounced "chee gung") is the authentic cultivation of "Qi" (or "Chi") which means "vital energy of the body." In Chinese, "gong" means the skill and achievement cultivated through regular and disciplined practice. Qigong is an important part of traditional Chinese medicine (TCM) for maintaining wellness, preventing disease and treating disease through self-care practice or by receiving external Qi from a Qigong therapist. In ancient China, the practice of authentic Qi cultivation was associated with the theory of energy flow within the body, described in the Suwen (Basic Questions) of the Huangdi Neijing (The Inner Classic of the Yellow Emperor) and with the discovery of acupuncture meridians as described in the Ling Shu (The Spiritual Pivot). The practice of Qigong combines breathing, movement and meditation and therefore is often classified by Western providers under the category of "mind/body medicine." Qigong is an ancient technology of mind-body management and the refinement of one's vital energy for optimal health and for personal development [1]. Previous studies suggest that Qigong may be a beneficial adjunct treatment for individuals with type 2 diabetes mellitus (T2DM) and have shown consistent and statistically significant positive associations between participation in Qigong and blood glucose, triglycerides and total cholesterol [2]. Qigong has also been associated with trends in weight loss, reduced BMI and improved insulin resistance in people with T2DM [3]. Systematic reviews have found support for a role

68 Chinese Medical Therapies for Diabetes, Infertility, Silicosis and the Theoretical Basis

T2DM is a complex, chronic metabolic disease with hyperglycemia arising from insulin resistance, progressive pancreatic beta cell failure and insufficient insulin secretion. According to the International Diabetes Federation (IDF), more than 371 million people worldwide have diabetes and over 550 million people are projected to have diabetes by 2030 [6]. In adults, T2DM accounts for about 90–95% of all diagnosed cases of diabetes [7]. Common symptoms of T2DM include excessive thirst, frequent urination, excessive hunger, fatigue, weight loss, blurry vision, slow-healing sores, frequent infections (bacterial, yeast, or fungal overgrowths thrive on excess sugar in the body) and areas of darkened skin, usually in the armpits and neck which can be a sign of insulin resistance [8]. T2DM is often associated with hypertension, dyslipidemia and atherosclerosis and if not managed can lead to complications including stroke, cardiovascular disease, peripheral vascular disease, neuropathy and kidney failure [9]. Concurrent hypertension with diabetes significantly raises the risk of coronary artery disease, stroke, retinopathy and sexual dysfunction [10]. According to the American Diabetes Association, having diabetes nearly doubles the chance of having a heart attack [9]. Diabetes causes more deaths a year in the United States than AIDS and breast cancer combined [11]. In 2010 in the United States alone, about 73,000 lower-limb amputations were performed on adults with diabetes and peripheral vascular disease [12]. T2DM can substantially diminish quality of life, decrease life expectancy and increase health problems and healthcare costs. A study reported that the estimated total economic cost of diagnosed diabetes in 2012 in the United States was \$245 billion. This estimate highlights the substantial burden that diabetes imposes on society [13]. The incidence of T2DM continues to rise by epidemic proportions and has The exact cause of T2DM is unknown, but researchers tend to agree that genetic, dietary and lifestyle factors play a role in T2DM [14]. People with a family history of diabetes or who are obese are at the highest risk of developing the disease [8, 9]. Genes associated with T2DM have often been linked to pancreatic beta cells and impairments in beta cell mass and in insulin secretion [15]. The risk of developing T2DM increases when a parent or sibling has the disease [8]. Because population-level genetic changes take many generations to occur, the epidemic proportions of T2DM are almost certainly primarily a consequence of recent environmental changes; nonetheless, T2DM does appear to occur preferentially in genetically predisposed populations, which suggests that the effects of preexisting susceptibility genes have been triggered by recent shifts in nongenetic factors [16]. The environment has great biological impact on human health and disease. There is a growing body of literature suggesting a role for epigenetic factors in the complex interplay between genes and the environment, particularly in common complex disorders, like T2DM [16]. Studies have demonstrated that nutrients can reverse or change epigenetic phenomena such as DNA methylation and histone modifications, thereby modifying the expression of critical genes associated with physiologic and pathologic processes [17].

An improper diet (high in sugar, carbohydrates and fats) and inadequate exercise are contributing factors in the onset of T2DM. The common use of high-fructose corn syrup in foods over the past hundred years has correlated closely with the increasing prevalence of metabolic syndrome, obesity and T2DM, possibly because fructose can alter satiety and lead to the urge to eat more than one ordinarily would [18]. Fructose may also lower metabolism and alter how fat is stored and give rise to the buildup of visceral fat [18]. Fat distribution in the body is important; if fat is stored primarily in the abdomen as opposed to the hips and thighs, there is a higher risk of developing fatty liver, insulin resistance and T2DM [8, 9, 19]. Fatty liver is associated with metabolic syndrome and insulin resistance [9, 19]. One can have fatty liver and not be overweight. If one is overweight and has acquired insulin resistance, losing weight and lowering blood glucose levels through exercise and dietary changes can improve insulin resistance [9, 19]. Exercise is important for regulating one's body weight. Physical activity acts like insulin in that it uses up glucose. Physical activity also makes the body's cells more sensitive to insulin [8].

Obesity is a major risk factor in T2DM because obesity can lead to metabolic disorder and insulin resistance [14]. Many obese people do not develop diabetes, but most people who have T2DM are obese. It is important to point out that people who are not overweight can develop T2DM [11, 15]. Sometimes people who do not appear to have noticeable symptoms may have T2DM and be undiagnosed for many years until complications arise [8]. A high body mass index (BMI) and insulin resistance are primary cofactors in T2DM, but some researchers suggest that the disease could be linked to the pancreatic beta cells themselves, whether due to a reduction in the number of insulin-secreting cells or due to an impairment of beta cell function [15]. In a healthy person, the pancreatic beta cells secrete insulin into the bloodstream and the insulin circulates and enables sugar to enter into the body's cells for the production of energy [8]. Insulin lowers the amount of sugar in the bloodstream and as the sugar level drops, the pancreas also decreases insulin secretion [8]. In T2DM, this process is impaired because as sugar builds up in the bloodstream the pancreatic beta cells release more insulin but over time the beta cells cannot manage the high levels of blood sugar and they start to lose their function [8].

Excess sugar in the blood can affect nerve conductivity by impairing the tiny blood vessels that nourish the nerves leading to neuropathy or sensations of tingling, numbness, burning or pain, especially in the extremities. Over time it can lead to the loss of blood flow to the extremities and develop into gangrene [8]. One of the early signs of nerve and blood vessel damage from T2DM in men is erectile dysfunction [8, 9, 20]. The damage to tiny blood vessels can also lead to retinopathy, blurry vision, eye damage and even blindness [8, 9]. Similarly, high blood glucose levels can injure the delicate blood vessels that make up the filtration system of the kidneys which can lead to irreversible damage and end-stage kidney failure that requires dialysis or a kidney transplant [8, 9].
