Community Medicine / Fourth Stage / Dr. Ali / Lecture 18
Epidemiology of Diabetes Mellitus
• Diabetes mellitus is a metabolic disorder of multiple etiology characterized by
chronic hyperglycemia with disturbances of carbohydrates, fat and protein
metabolism resulting from a defect in insulin secretion, insulin action or both.
Why diabetes is important?
• Diabetes is a common disease.
• There is evidence that the overall worldwide prevalence of diabetes is gradually
• Diabetes causes great morbidity and early mortality in a large number of people,
since it is associated with many complications.
• The cost of managing the complications of DM is high.
Burden of DM
• Diabetes prevalence is increasing in the developed world due to aging of the
popul ation, and in the developing world due to increased urbanization
accompanied by cultural and socio -economic changes . Experts estimated that the
number of adults with diabetes will reach 300 million in the year 2025, more than
75% of them (i.e. 228 million ) will be in the developing countries.
Global Prevalence Estimates, 2000 and 2030
0.0% 1.0% 2.0% 3.0% 4.0% 5.0%2000
Economic BurdenIt is estimated that the cost of caring for people with diabetes is 2 -4 times the cost of
caring for non -diabetic people in most health care systems . In 1992 a study in the US
concluded that more than US $ 100 billion was spent on overall health care of people
Types of DM
Type 1 DM
- Accounts for 10% of all patients
- Destruction of B -cells
- Absolute insulin deficiency
- Mostly at ages <30 years (it can occur at any age)
• Forms of Type 1 :
A- Autoimmune :
- Presence of autoimmune markers ( ICAs, IAAs, Autoantibodies to GAD65)
- Strong HLA association
- There is a genetic element
B-Idiopathic : (no known cause)
- Only minority of patients fall in this group
- Occurs in individuals of African& Asian origin
Developing countries Developed countries
Number of persons with diabetes in 2007
- Strongly inherited
- Lacks autoimmune markers
- No HLA associated
- Most common (90%)
- After age of 40 years
- Predominant insulin resistance with relative insulin deficiency, ultimately loss of B-
cells mass can lead to insulin dependency
- Onset is insidious
- Due to genetic factors, environmental factors or both.
Other specific types:
- Genetic defects of Beta -cells: onset at early age (<25 years). Inherited as an
autosomal dominant pattern. Previously known as maturity onset diabetes of
- Diabetes secondary to diseases of the pancreas or endocrinal diseases & drugs.
• Gestational diabetes
Complications of DM
Cardiovascular disease (i.e. macrovascular complications) is the cause of death in 75 -80%
of patients with type 2 DM)
Diagnosis of DM• Fasting plasma glucose >126mg/dl (7mmol/l)
• 2 hours postprandial plasma glucose >200mg/dl
• Any random plasma glucose >200mg/dl ( 11.1 mmol/l) , together with polyuria,
polydypsia, weight loss, and visual blurring
• Must confirm diagnosis with two abnormal plasma glucose results on separate
• Glycosylated hemoglobin (HbA 1c)
- reflection of how well the glucose has been controlled.
- hyperglycemia causes an increase in HbA 1c
- values expressed in percentages,
* with non -diabetic 5.5 to 7%,
* diabetic with good control 7.5 to 11.4%
* diabetic with moderate control 11.5 to 15%
*dia betic with poor control greater than 15%
Impact of Diabetes Mellitus
A 2-to 4-
in working -
cause of non -
Diagnosis of Impaired Glucose Tolerance
• Impaired glucose tolerance was defined by the Expert Committee as:
– Fasting Plasma glucose of 110 -125mg/dl
– 2-hour post glucose load 140 -199mg/dl
• Genetic factors
- Twin studies indicate a very strong genetic component to the etiology of type 1
DM. It is more common in those with certain HLA types.
- Twin studies also demonstrate a greater than 30% concordance among
monozygotic twins pairs in the expression of type 2 DM.
- Certain racial groups , as African Americans, Hispanics, and Native Americans, are
at increased risk for type 2 diabetes.
• Age : Incidence of type 2 DM increases with increasing age.
• Physical inactivity : Lack of exercise may alter the interacti on between insulin and
its receptors and subsequently leads type 2 DM.
– Vigorous exercise > 1/week, 25% risk reduction (Manson & al, Lancet 1991,
338; 774 -8., JAMA, 1992, 268,63 -7)
– Looking TV 2 -10 hours per week: RR 1.66 of having DM compared with 0 -1
hour per week
( HU et al; Arch Intern Med 2001;161: 1542 -1548)
• Obesity : Incidence of type 2 DM increases with increasing body mass index.
Obesity can induce resistance to the action of insulin.
– RR risk of DM in females (ref. BMI < 22)
• 22 -23 3.0
• 24 -25 5.0
• > 31 40
(Colditz & al, Ann Int Med, 1995, 122; 481 -6)
• Drugs & hormones: Long list of drugs that affect carbohydrate metabolism had
been identified. e.g. Phenytoin, diuretics (thiazide type), corticosteroids. Oral
contraceptives, and beta -adrenergic blocking agents.
• Pancreatic disorders: Inflammatory, neoplastic, and other disorders of the
pancreas e.g. cystic fibrosis, and pancreatectomy.
• History of gestational diabetes or delivery of large babies.
Diabetes Mellitus Treatment
Maintain quality of life.
Prevent further complications.
• Primary prevention: Primary prevention of type 2 DM can be achieved by:
- Promotion of healthy nutrition: Encourage low saturated fat, high fiber diet .
- Smoking cessation
- Correction of obesity: Encourage weight loss to keep BMI<30
There are two approaches for primary prevention:
• The high risk approach:
This is directed to high risk people such as those with family history of type 2 DM,
obes e individuals, and those with previous abnormalities of glucose tolerance including
• The population approach:
This is based on altering the environmental risk factors and determinants of type 2 DM
in the whole population through public education
This level of prevention aims at early detection of asymptomatic cases
• Early detection and treatment
• Screening for gestational diabetes
• Screening for susceptible groups
Screening for diabe tes:
- Screening all adults over 40 years of age with fasting plasma glucose every 2 -3
- Begin screening at earlier age with a positive family history, obesity, or symptoms
The community should be involved in diabetes awareness and screening
Tert iary prevention
• This involves treatment of already established cases of diabetes
• What are the objectives of treatment of diabetes?
- To relieve symptoms
- To reduce mortality and economic costs of diabetes
- To prevent as much as possible acute and long term complications and to monitor
the development of such complications and to provide timely intervention
- To improve the quality of life and productivity of the individual with diabetes
Goals of diabetes management
Goal s for chronic diabetes may be somewhat different for good control, not ideal goals
which are normal for a non -diabetic
Acceptable Ideal (normal) intervention
<140 mg/dl <125 mg/dl FPG
< 7 < 6 HbA1C
< 140/90 < 130/80 Blood pressure
< 240 mg/dl < 200mg/dl S. Cholesterol
< 130 mg/dl < 100 mg/dl LDL cholesterol
No smoking No smoking Stop smoking
BMI <30 BMI <25 Decrease weight
Daily 30 min. Daily 30 -60 min. Daily exercise
Patient and family counseling
Patients and their families should be aware of the following:
• The disease is permanent, life -long treatment is required
• Control of blood sugar to delay appearance of microvascular complications
• Importance of foot care
- Wash & dry feet daily
- Soften & gently reduce calluses
- File (but not cut) nails
- Wear shoes that are soft and well fitting
- Never walk barefoot
- Notice & deal with small injuries or signs of pressure
• Management of hypoglycemic attacks• Injection technique (when insulin used) and rotation of sites
• Counseling in family planning if poss ible
• Lifestyle modification:
- smoking cessation
- Diet control
- Weight loss
- Increase Physical activity
- Social and psychological factors