I.Introduction: Definition of Obesity and Types of Diabetes
II.Type Two Diabetes: Symptoms and Consequences
III.Intense Link between Type Two Diabetes and Obesity
IV.Obesity and Type Two Diabetes in Modern Society
V.Prevention and Treatment of Type Two Diabetes
I.Introduction: Definition of Obesity and Types of Diabetes
To date, obesity and diabetes are two concepts that are often juxtaposed inpathological discussions. The first record of the discussions about obesity can be traced back to the Paleolithic Stone Age which was an epoch of about 25 thousand years ago from today. Obesity was not considered a problematic condition of sickness until 2013 when the American Medical Association listed it among the most common and serious health problems in the modern American Society. The widespread phenomenon of obesity has continued to grow increasingly epidemic across the globe at a rate that was unprecedented, as the lifestyle and the eating habit of people were increasingly unbalanced.One key reason is that obesity increases the possibility of other more serious diseases, such as heart disease, acertain type of cancers and type 2 diabetes (which we will discuss it further). Another reason is the prevalence speed of obesity is accelerating around the world at an unprecedented rate as an epidemic disease, based on a research conducted by Joint Health Surveys Unit onbehalf of the Department of Health in 1999 (Figure 1). we can observe that the explosive speed of obesity prevalence and more women than men become obese. More recently, in the 21 century, there was another study in The Lancet demonstrated the global trend of obesity prevalence. It emphasized that just in one year back in 2010, the negative impact of both diseases were so fatally that they contributed to a lot of the deaths of many. In fact it was estimated that the two were responsible for over 3.5 million patients passing away, and the number of death cases was about 3-9% in proportion to the total number of patients that had diabetes and obesity. About 3 to 8% of the global patients develop disability-adjusted-life-years, which showcasedthe aftermath of obesity and overweight on patients that did not eventually decease.
Figure 1Increase of obesity in the UK (1980 -1997).
Obviously, the feature of obesity is over-weight, that is why the definition of obesity generally is a therapeutic situation where the accumulated excess amount of body fat might be detrimental to human health.Body mass index (BMI), (Table 1)using anequation dividing a person's weight by the square of the person's height, is a standard value to classify the obesity. Some East Asian countries like China and Japan use lower standard.
Table 1. World Health Organization classification of obesity.
The spread of obesity has been increased by many factors as indicated in the table, at a rate that was much faster compared to that of the last century.One of the hypothesis of the increase in patients’ diabetes was attributed to errors of bodily functions in particular to metabolism.The person that introduced such hypothesis also challenged long-established idea that kidney deposit is one of the major causative factor of obesity. Type 1 diabetes usually means that the state of the patient's body cannot produce sufficient insulin because of failure in the immune system, which mistakenly eliminated insulin-producing cells, meaningthat their bodies cannot defend patients from the harm of viruses, invasive substances and bacteria that are incongruent with the functioning of human body.
The spread of obesity has been increased by many factors as indicated in the table, at a rate that was much faster compared to that of the last century. One of the hypothesis of the increase in patients’ diabetes was attributed to errors of bodily functions in particular to metabolism. In the meanwhile, the diabetes was hard to be diagnosed since their characterizations are not so obvious.In the history, Thomas Sydenham,the person that introduced such hypothesis also challenged the long-established idea that kidney deposit is one of the major causative factor of obesity, as well as another epidemic disease, diabetes.That is true since diabetes is such a situation wherethe glucose in your blood, also called blood sugar, is too high.
Besides some special cases, there are mainly three types of diabetes: type 1 diabetes, type 2 diabetes, and gestational diabetes. (A) Type 1 diabetes used to be called juvenile diabetes.Type 1 diabetes usually means that the state of the patient's body cannot produce sufficient insulin because of failure in the immune system, which mistakenly eliminated insulin-producing cells, meaning that their bodies cannot defend patients from the harm of viruses, invasive substances and bacteria that are incongruent with the functioning of human body. (B) Type 2 diabetes is the most common type of diabetes to date. In type 2 diabetes, however, the body still can produce insulin at a normal stage. The problem here is either insulin is not sufficient or our body fails to respond it (insulin resistance), resulting in the high level of glucose in the blood. In contrast to type 1 diabetes, the most of type 2 diabetes patients don’t have to take adaily dose of insulin to control the level of glucose. The number of people who get type 2 diabetes is rapidly increasing worldwide which can’t be ignored anymore.(C) As the name suggests, gestational diabetes is defined as diabetes that happens forthe first time in pregnancy. Women who get this type of diabetes will develop a resistant to insulin thus to have a build-up glucose.
II. Type Two Diabetes: Symptoms and Consequences
The commonest symptoms of type 2 diabetes areinsidious onset oftiredness, thirst, polyuria,weightloss, pruritus vulvae or balanitis; the patients are usually overweight or obeseand C-peptide detectable while havingno ketoacidosis.The diagnosis of type 2 diabetes have been subjected to failure for years, and there has been a lot of cases of under-diagnosis as well as complete inability to diagnose this disease among patients,even though they may be carrying such a serious problem. It was because the patients themselves were inclined to disregard insidious symptoms of this disease. 
Figure 2.Glycated hemoglobin(in %) and cardiovascular diseasequantitative data based on 4662 males (EPIC-Norfolk StudyFrom Khaw et al BMJ 2001; 322:15 – 18.)
Same as all the types of diabetes, the consequences of type 2 diabetes generally arediabetic complications.The mostfatal complication is cardiovascular disease.A considerable amount of epidemiological studies have claimed that there were apparently objective evidence of the positive correlation between glycemiaand macrovascular disease in a community (Figure 2).There are many other serve diseases such as kidney disease (caused by damaging small blood vessels), eye disease (can damage vision even provoke blindness), nerve damage (causing troubles in digestion and urination) and so on.
The serious consequences are promoting people to pay more and more attention to this chronic type 2 diabetes.
III. Intense Link between Type Two Diabetes and Obesity
As one of thesymptoms of type 2 diabetesis that the patients are usually overweight or obese, some questions should be naturally raised that whether diabetes are connected to cases of obesity? If so, is there any valid evidence?
The Answers are yes.
Firstly, there is a lot of data evidence. As early as 1978, West has demonstrated that the upsurge of popularity of type 2 diabetes have been associated with a strong trend of obesity that was increasingly prevalent in a group of peopleAmongthe same populations,there's also been clear evidence that the risk of getting diabetes will be higher among patients whose problems of obesity were already well proven. The data-value from Health Professionals follow-up study regarding men and the data of women from the Nurses’ Health Study have graphically represented how the increasing propensity of type 2 diabetes Is followed by the increased popularity of obesity Showing a positive correlation between them (Figure 3). At the meanwhile, the data curve showed that for women, the risk of diabetes increases faster than men when the BMI is at the same stage. So obese women are more sensitive to getting type 2 diabetes.
Figure 3.Relative risk of type 2 diabetes with increasing BMI.
Secondly, there is also a biological link, which is the fundamental reason, between the type 2 diabetes and obesity. In 2001, Lazar reported on Nature that resistin is a potentialhormone linking obesity to type 2 diabetes,which was a major breakthrough in the relationship between type 2 diabetes and obesity. After 15 years’ development, the pathophysiology of obesity-inducedtype 2 diabetes has shown the complicated mechanismsin a clearer manner. Among different hypothesis, there have been two major theories that expounded on the causative relationship between excessive amount of fat and its consequential impact on the function of metabolism related to impaired glucose. The first one is ‘Randle’s cycle’,whichelucidates the reversibly application of the associable correlation between glucoseoxidation and fatty acid oxidation. Another one is the ‘ectopic fat storage hypothesis’, which is based on the impairedinsulin effect as a result of deposition of lipids that takes place in insulin-target tissues. Both researchers coinedthe well-known ‘lipotoxicity theory’ and propose a realisticframework of metabolic mechanism in whichlong termstorage of excessive fat increases with lowering ofinsulin secretory capacity of beta cells and insulin resistance.