An Update on the Etiology and Epidemiology of Diabetes Mellitus

Abstract

Diabetes mellitus is one of the most common endocrine disorders affecting almost 6% of the world's population. The number of diabetic patients will reach 300 million in 2025 (International Diabetes Federation, 2001). More than 97% of these patients will have type II diabetes. The projected increase in the number of diabetic patients will strain the capabilities of healthcare providers the world over. Thus it is of paramount importance to revisit the causes and epidemiology of diabetes mellitus. Diabetes mellitus is caused by both environmental and genetic factors. The environmental factors that may lead to the development of diabetes mellitus include physical inactivity, drugs and toxic agents, obesity, viral infection, and location. While type I diabetes is not a genetically predestined disease, an increased susceptibility can be inherited. Genetic susceptibility plays a crucial role in the etiology and manifestation of type II diabetes, with concordance in monozygotic twins approaching 100%. Genetic factors may have to be modified by environmental factors for diabetes mellitus to become overt. An individual with a susceptible gene may become diabetic if environmental factors modify the expression of these genes. Since there is an increase in the trend at which diabetes prevail, it is evident that environmental factors are playing a more increasing role in the cause of diabetes mellitus. The incidence of type I diabetes ranged from 1.9 to 7.0/100,000/yr in Africa, 0.13 to 10/100,000/yr in Asia, approximately 4.4/100,000/yr in Australasia, 3.4 to 36/100,000/yr in Europe, 2.62 to 20.18/100,000/yr in the Middle East, 7.61 to 25.7/100,000/yr in North America, and 1.27 to 18/100,000/yr in South America. The epidemiology of type II diabetes is equally bleak. The prevalence of type II diabetes ranged from 0.3 to 17.9% in Africa, 1.2 to 14.6% in Asia, 0.7 to 11.6% in Europe, 4.6 to 40% in the Middle East, 6.69 to 28.2% in North America, and 2.01 to 17.4% in South America.

Mechanisms by which diabetes increases cardiovascular disease

“…The incidence of diabetes and diabetes-related atherosclerosis has dramatically increased over the past years [3]. Even though prevention of diabetes by a reasonable life style should be the first step in fighting this epidemic, it is unlikely to be sufficient [4].…”

“…Even though prevention of diabetes by a reasonable life style should be the first step in fighting this epidemic, it is unlikely to be sufficient [4]. Considering the overlap of pathogenetic mechanisms of diabetes and atherosclerosis, it seems promising to identify therapeutic targets shared by both diseases [2,3].…”

“…Different molecular mechanisms associated with hyperglycemia have been identified including 1. increased glucose flux through the polyol pathway [5], 2. formation of advanced glycation end products (AGE) [5], (3) activation of protein kinase C (PKC) [5,6], 4. increased glucose flux through the hexosamine pathway [5], and activation of the 12/15-lipoxygenase (12/15-LO) pathway [7,8]. All these mechanisms finally lead to increased superoxide formation [5] (Figure 1).…”

“…The majority of diabetic patients (>90%) suffer from type 2 diabetes [3], a progressive insulin secretory defect on the background of insulin resistance [4]. Type 1 diabetes is an autoimmune disease associated with progressive and often complete β cell destruction [3], lacking insulin production due to autoimmune destruction of pancreatic β-cells [4]. Type 1 diabetics require treatment with insulin [4].…”

Menopausal hormone therapy and new-onset diabetes in the French Etude Epidemiologique de Femmes de la Mutuelle Générale de l’Education Nationale (E3N) cohort

“…Diabetes mellitus is one of the most common chronic diseases in the industrialised world [1]. In France, the prevalence of treated diabetes was estimated to be 3.6% in 2005 [2].…”