Diabetes Mellitus is defined as a metabolic abnormality characterized by hyperglycaemia and disturbances of carbohydrate, fat and protein metabolism that are associated with absolute or relative deficiency in insulin secretion and /or insulin action .
When fully evolved, it is characterized by fasting hyperglycaemia but it can also be characterized in the less overt stages and before fasting hyperglycaemia appears,most usually by the appearance of glucose intolerance.
Most often, it tends to be asymptomatic (“silent killer”) in which case the diagnosis depends on biochemical investigations
The two most important determinants of diabetes are
- firstly genetic background (family history) and
- secondly obesity.
It has been very aptly said that for diabetes, “genetics loads the cannon and obesity finally fires it”.
As for IHD, the risk factors may be grouped as “ Non Modifiable ” (Age, Sex, Genetic and Racial factors) and “ Modifiable ” (Obesity, physical activity,nutritional factors, stress, drugs, infections and chemical toxins, etc).
Race :South Asian populations including Indians may be at high risk.One hypothesis is that this may be due to the effect of “ thriftygenes ”. These genes developed as a part of nature’s protective mechanisms, among populations who were for many centuries exposed to starvation, famines and lack of food. The thrifty gene was developed by nature to conserve whatever small amount of energy, which was available to such populations, in the form of body fat stores. However, with economic improvements in such populations, the food supply improves greatly but the protective effect of thrifty gene also continues resulting into excessive levels of obesity and consequent diabetes.
Obesity : Obesity has been proven to be a very strong risk factor for diabetes type 2. The estimates of risk vary from RR of 1.8 to 3.2 in different populations. The role of obesity is independent of racial factors. In addition, central distribution of body fat (referred to as central, abdominal, visceral, apple - shaped or android type of fat distribution and measured in terms of Waist Circumference or Waist Hip ratio) is upheld to be an important risk factor, independent of total body weight.
Physical inactivity : It has been clearly demonstrated that physical activity increases insulin sensitivity. The risk of diabetes due to physical inactivity has been estimated to be as high an RR of 4.31 in some large scale studies. The protective effect of physical activity is independent of obesity; this means that an obese person who is physically active and fit would have lower risk of diabetes (as well as lower risk of other lifestyle diseases)
Nutritional Factors : There is increasing evidence from both epidemiological as well as laboratory studies that increased dietary intake of saturated fat and decreased intake of fibre can result in lowered insulin sensitivity and impairment of glucose tolerance. In general, reduction in the overall calories,reduced intake of saturated fats & refined sugars and increased intake of grains, fruits and vegetables would be of utility in preventing diabetes.
Foetal and Early Childhood Influences : poor maternal nutrition during pregnancy, and malnutrition during early infancy may be associated with insulin resistance, obesity, impaired glucose tolerance, raised blood pressure and occurrence of metabolic syndrome in the same person during his / her adult life.
Metabolic syndrome represents a set of risk factors that predispose individuals to both cardiovascular disease and diabetes.
Metabolic syndrome factors include abdominal obesity, atherogenic dyslipidemia (elevated triglyceride levels, smaller LDL particle size, and low HDL cholesterol), raised blood pressure, insulin resistance (with or without glucose intolerance) and prothrombotic and proinflammatory states
Primary Prevention : This would basically utilize the Information, education and Communication (IEC) strategy to educate and motivate the community and individuals
Population strategy- educating both, the general community ( mass approach ) and specific groups ( group approach )
Individual high risk strategy- focusing on individuals who have strong family history of diabetes mellitus, who are changing from active to more leisurely lifestyle (as the newly rich), are obese, have evidence of IFG or IGT, have other cardiovascular risk factors as hypertension and dyslipidaemia, and women who have history of Gestational DM or history of giving birth to babies weighing > 4kg.
Secondary Prevention : This would be through early diagnosis and prompt treatment, mainly by way of screening programmes
Population screening by screening the entire population or a selected random sample,which is fruitful only if the prevalence of diabetes is very high or else for research or health planning purposes.
Selective screening undertaken in groups of people known to be at high risk, as those with family history, obese persons (BMI > 25), aged more than 40 years in high prevalence populations, women giving history of GDM, those with history of IGT / IFG, or those with hypertension or dyslipidaemia.
Opportunistic Screening employed when high risk individuals come in contact with the Doctor, e.g. obese person, hypertensive, having IHD, having family history, etc. once such a person reports sick.
Similarly, in clinical settings, all opportunities should be utilized to undertake screening for known end organs as ophthalmoscopy, urine testing, etc., to detect any evidence of such end organ damages which could have occurred and may have escaped detection till now.
Tertiary Prevention : The role of Doctors as well as paramedical personnel assumes importance in context of tertiary prevention
- to follow up the patient,
- to advocate continuous treatment,
- to educate the patient about importance of treatment and
- the various precautions to be taken by them.
Presence of diabetes is considered to be a major risk factor for development of IHD and other CVD and hence the need to have a tight control on blood sugar levels for prevention of IHD/CVD.
Moreover, the complications of diabetes particularly CVD are much higher if concomitant hypertension is also present and hence the need of monitoring and adequate control of blood pressure in all diabetics as a part of tertiary prevention.