Introduction
According to the World Health Organization, 5% of the total world population has diabetes. The global mortality rate for diabetes in 2004 was .5%, more than 80% of the deaths occurred in developing countries, and the death rate is projected to double by the year 2030. A healthy diet, regular exercise, low BMI, and avoiding tobacco can prevent the incidence, morbidity and mortality of diabetes (World Health Organization).
Diabetes is a chronic metabolic disorder that affects the way the body produces or uses insulin and that results in high levels of glucose circulating in the blood.
The pathogenesis of the disease differs according to aetiology, and the disease has been classified accordingly. Type 1 diabetes is an autoimmune disease where the pancreas cannot produce insulin; its onset is severe and acute and it is fatal unless treated with insulin. Symptoms include frequent urination, increased thirst and hunger, and weight loss. Type 1 diabetes used to be called juvenile or childhood-onset diabetes because it was associated with this group of patients. Type 2 diabetes mellitus (T2DM), develops when the body is not able to use insulin effectively; its onset is mild-severe and is often insidious (World Health Organization).
Some of the symptoms of T2DM overlap with those of Type 1 diabetes and as a result may escape diagnosis until it has advanced to critical stages. T2DM has been linked to obesity and physical inactivity. It also used to be linked to age, appearing only in adults, but the disease is now seen in more and more children. The incidence of Type 2 diabetes is much lower than that of Type 1 diabetes; however, it is a great health concern because of the dramatic increase in the global incidence of T2DM. This phenomenon may be explained by the aetiology of the disease (World Health Organization).
Discussion
As with most other disease, the pathogenesis of diabetes is closely linked with its aetiology; and although these will be discussed separately, the connection remains.
Pathogenesis of T2DM
The consequences of diabetes can lead to a number of life-threatening or crippling diseases. Major pathologies associated by diabetes include cardiovascular, eye, neurological, and kidney diseases.
Cardiovascular disease. Heart disease and stroke are the main cause of death for people with T2DM, accounting for half the deaths of people with diabetes. (Janghorbani, 2012). A Japanese study found a strong association between Type 2 diabetes and ischemic stroke events. Individuals with impaired glucose tolerance also showed an increased risk of a cardiovascular event (Saito, 2012).
Diabetic retinopathy. Chronic diabetes damages the eyes and results in blindness or severely impaired vision in 12% of patients (World Health Organization).
Neuropathy. Diabetes damages the nerves causing pain and weakness in the hands and feet; which combined with poor blood circulation may cause foot ulcers and may require amputation if left untreated (World Health Organization).
Nephritic disease. The second major cause of death for people with diabetes is kidney failure in 10-20% of patients (Saito, 2012).
Diabetes is a deadly disease with a very complicated pathophysiology. But knowing the pathology of a disease is one thing, understanding the aetiology is another.
Aetiology of T2DM
A strong correlation has been found between diet, BMI, and exercise, and the onset of Type 2 diabetes mellitus (Saito, 2012). A correlation has also been shown between T2DM and a variety of other factors, including social, ethnic, and genetic factors (Gangwisch, 2007)
Obesity. The world is getting fat. Obesity has been associated with Type 2 diabetes mellitus and is the number one factor associated with obesity in children (5-19 yr). Some factors that are driving obesity in children include socioeconomic status, poor nutrition, western diets, stress, and lack of exercise. The best approach to combat this disease is to get parents and schools involved. Parents have control of diets, and schools have control of health and physical education programs. Aggressive screening programs are also recommended to identify those at risk; for example, children with obese parents (Gupta, 2012). Glucose levels have been found to be significantly higher in the breast milk of mothers diagnosed with T2DM (Whitmore, 2012).
Diet. Diet and obesity are strongly linked, so it is natural to find a correlation between diet and T2DM. A study in an African American urban population found a link between the high prevalence of obesity and T2DM in this population, and low levels of exercise and intake of nutrients. There was a lack of fruits, vegetables and grains in their diets, and their consumption increased with socioeconomic status (Jen, 2007).
Morbidly obese patients who undergo bariatric surgery have been able to resolve T2DM. However, the disease sometimes reappears in a number of patients. A study in rats with T2DM showed that a high fat diet revered the therapeutic effect of bariatric surgery. Patients who wish to retain the therapeutic effect of bariatric surgery should avoid a high fat diet (Liu, 2012).
Exercise. Patients with the highest BMI also have the lowest rate of activity; and a strong inverse relationship has been shown between exercise and T2DM (Stefanov, 2011).
Social factors. Socioeconomic position (SEP) may be the most strongly correlative factor in the prevalence of T2DM and mortality, and it impacts women more than in men (Espelt, 2011; and Thomas, 2012). Inadequate SEP prevents access to proper food, health services, and limits time for physical activities.
On the other hand, social support has been shown to help diabetic patients adhere to their treatment protocol (Gomes-Villas Boas, 2012). Furthermore, an interesting study found that religious Moslem and Christian had better glycaemic control than patients who practiced other religions (How, 2011).
Ethnicity. People from India who immigrate to Singapore tend to be at higher risk of developing diabetes (Zheng, 2012). This may be attributed to a combination of social and dietary factors.
Summary
We have evaluated a number of factors associated with Type 2 diabetes mellitus: nutrition, exercise, obesity, SEP, ethnicity, and religion. However, as studies on the aetiology of T2DM continue, new factors are being uncovered that underscore the complexity of this disease.
A study by Millar and Dean (2012) on the origin of T2DM in Canadian children helps illustrate just this. The Aboriginal Oji-Cree people have one of the highest incidences of T2DM in the world. The study found a strong connection between the intrauterine environment and subsequent development of diabetes: babies with obese mothers, or whose mothers had Type 2 or gestational diabetes, tended to be at higher risk of developing T2DM later in life. However, the study also discovered that people of Oji-Cree heritage have a unique gene mutation that causes those affected to secrete less insulin.
This gene mutation poses a higher risk factor for the development of T2DM in the Oji-Cree people than any other known risk factors, including obesity, nutrition, and exercise.
It is clear that Type 2 diabetes mellitus is a complex disease that merits more study.
References
Espelt A, L Arriola, C Borrell, I Larrañaga, M Sandín, et al. “Socioeconomic position
and type 2 diabetes mellitus in Europe 1999-2009: a panorama of inequalities.” Curr Diabetes Rev. 7.3 (2011):148-58. Print.
Gangwisch JE, SB Heymsfield, B Boden-Albala, RM Buijs, F Kreier, et al.
“Sleep duration as a risk factor for diabetes incidence in a large U.S. sample.” Sleep 30.12 (2007): 1667-73.
Gomes-Villas Boas, LC, MC Foss, MC Freitas, and AE Pace. “Relationship among social
support, treatment adherence and metabolic control of diabetes mellitus patients.” Rev Lat Am Enfermagem. 20.1 (2012):52-8.
Gupta N, K Goel, Shah P, and A Misra.“Childhood obesity in developing countries:
epidemiology, determinants, and prevention.” Endocr Rev. 33.1 (2012):48-70.
How CB, KE Ming, and CY Chin. “Does religious affiliation influence glycaemic control
in primary care patients with type 2 diabetes mellitus?” Ment Health Fam Med.
8.1 (2011):21-8.
Janghorbani M, and M Amini. “Incidence of Metabolic Syndrome and Its Risk Factors
among Type 2 Diabetes Clinic Attenders in Isfahan, Iran.” SRN Endocrinol.
(2012):2012-167318. Epub 2012 Mar 15.
Jen, KL, K Brogan, OG Washington, JM Flack, and NT Artinian. “Poor nutrient
intake and high obese rate in an urban African American population with
hypertension.” J Am Coll Nutr. 26.1 (2007):57-65.
Liu, SZ, D Sun, GY Zhang, L Wang, Liu, et al. “A high-fat diet reverses improvement in glucose tolerance induced by duodenal-jejunal bypass in type 2 diabetic rats.”
Chin Med J (Engl). 25.5 (2012): 912-9. Print.
Millar K, and HJ Dean.“Developmental origins of type 2 diabetes in aboriginal youth in
Canada: it is more than diet and exercise.” J Nutr Metab. (2012):2012-127452.
Saito, I. “Epidemiological Evidence of Type 2 Diabetes Mellitus, Metabolic Syndrome,
and Cardiovascular Disease in Japan.” Circ J. (2012) Mar 27. [Epub ahead of
print]
Stefanov TS, AM Vekova, DP Kurktschiev, and TS Temelkova-Kurktschiev.
“Relationship of physical activity and eating behaviour with obesity and type 2
diabetes mellitus: Sofia Lifestyle (SLS) study.” Folia Med (Plovdiv) 53.1
(2011):11-8.
Thomas C, CM Nightingale, AS Donin, AR Rudnicka, CG Owen, et al. “Socio-economic
position and type 2 diabetes risk factors: patterns in UK children of South Asian, black African-Caribbean and white European origin.”PLoS One. 7.3 (2012): e32619. Epub 2012 Mar 7.
Whitmore TJ, NJ Trengove, DFGraham, and Hartmann PE. “Analysis of insulin in
human breast milk in mothers with type 1 and type 2 diabetes mellitus.”
Int J Endocrinol. (2012): 2012-296368. Epub 2012 Mar 5.
World Health Organization. “Diabetes Fact Sheet No312.” http://www.who.int/mediacentre/factsheets/fs312/en/
Zheng Y, EL Lamoureux, MK Ikram, P Mitchell, JJ Wang, et al . “Impact of migration and acculturation on prevalence of type 2 diabetes and related eye complications in indians living in a newly urbanised society.“ PLoS One. 7.4 (2012):e34829. Epub 2012
