This document provides an overview of diabetes mellitus, including the different types of diabetes, diagnostic criteria, epidemiology, natural history, screening, and prevention. It describes Type 1 diabetes as immune-mediated and requiring insulin treatment, while Type 2 is more common and often associated with obesity and aging. India has a high prevalence of diabetes, accounting for many children with Type 1. Risk factors include genetics, obesity, physical inactivity, and various infections or chemicals that can damage pancreatic beta cells. Screening high-risk groups and early treatment aim to prevent complications through managing blood glucose and self-care.

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DIABETES MELLITUS – AN
EPIDEMIOLOGICAL OVERVIEW
- DR. SOMAK MAJUMDAR
M.D,
DEPTT. OF CFM, AIIMS PATNA

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INTRODUCTION
Definition - It is a heterogeneous group of
disorders characterized by hyperglycemia,
and disturbances of carbohydrate, fat and
protein metabolism with absolute or relative
deficiency of insulin action and or secretion
a number of complications - cardiovascular,
renal, neurological, ocular and others such
as intercurrent infections.

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INSULIN PRODUCTION AND ACTION

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TYPE 1 DIABETES
 Aka Insulin-dependent diabetes mellitus
 most severe form of the disease.
 onset is typically abrupt
 usually seen in individuals less than 30 years of age
 immune-mediated in over 90 per cent of cases and idiopathic in less than
10 per cent cases.
 associated with ketosis in its untreated state.
 occurs mostly in children, the incidence is highest among 10-14 year old
group, but occasionally occur in adults.
 catabolic disorder in which circulating insulin is virtually absent, plasma
glucagon is elevated, and the pancreatic cells fail to respond to all
insulinogenic stimuli.
 Exogenous insulin is therefore required to reverse the catabolic state,
prevent ketosis, reduce the hyperglucagonaemia, and reduce blood glucose

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TYPE 2 DIABETES
 much more common than type 1.
 often discovered by chance.
 gradual in onset
 occurs mainly in the middle-aged and elderly,
 frequently mild, slow to ketosis
 compatible with long survival if given adequate
treatment.
 clinical picture is usually complicated by the presence
of other disease processes.

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8. + THE WHO RECOMMENDATIONS FOR THE DIAGNOSTIC
CRITERIA FOR DIABETES AND INTERMEDIATE
HYPERGLYCAEMIA

9. + SYNDROME X

10. + CUT-OFFS FOR SYNDROME X

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EPIDEMIOLOGY

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TOP 10 COUNTRIES BY PREVALENCE %
OF DIABETES

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DIABETES IN INDIA
 The population in India has an increased susceptibility to diabetes
mellitus.
 The rates of diabetes in migrants from the Indian subcontinent have
consistently shown to exceed those of the local population
 Current estimates indicate that 8.2% of the adult population, or 72.1
million people, have diabetes, 65.1 million of whom live in India.
 Prevalence of diabetes in India-9.1%
 India accounts for the majority of the children with type 1 diabetes.

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NATURAL HISTORY - AGENT
 The underlying cause of diabetes is insulin deficiency which is
absolute in type 1 diabetes and partial in type 2 diabetes. This
may be due to a wide variety of mechanisms:
1. pancreatic disorders - inflammatory, neoplastic and other
disorders such as cystic fibrosis,
2. defects in the formation of insulin, e.g., synthesis of an abnormal,
biologically less active insulin molecule;
3. destruction of beta cells, e.g., viral infections and chemical
agents,
4. decreased insulin sensitivity, due to decreased numbers of
adipocyte and monocyte insulin receptors.
5. genetic defects, e.g., mutation of insulin gene; and
6. autoimmunity.

21. + NATURAL HISTORY - HOST
AGE • May occur at any age.
• prevalence rises steeply with age.
• Malnutrition related diabetes - young people.
• prognosis is worse in younger diabetics, earlier complications
SEX • Some countries (UK) – male = female
• South-east Asia – male > female
GENETICS • Type 1 diabetes = 50% concordance, not totally genetic but
associated with HLA- DR3, DR4, B8, B15
• Type 2 diabetes = 90% concordance, genetically strong but not
HLA associated.
IMMUNITY Evidence of both cell mediated and humoral immunity
OBESITY Central obesity, duration and degree of obesity, waist circumference,
waist-to-hip ratio, insulin resistance.
MATERNAL
DIABETES
• develop obesity in childhood,
• at high risk of developing type 2 diabetes at an early age.
• Increased risk of subsequent diabetes in the child

22. + NATURAL HISTORY - ENVIRONMENT
SEDENTARY LIFESTYLE – lack of exercise leads
to altered interaction between insulin and its
receptors.
HIGHER SATURATED FAT INTAKE – higher
insulin resistance, lower insulin sensitivity, higher
fasting insulin levels.
DIETARY FIBRES – minimum intake of 20 gm/day,
reduced glucose and insulin levels.
MALNUTRITION – partial failure of β cell function,
ALCOHOL – damages pancreas and liver,
promotes obesity.

23. + NATURAL HISTORY - ENVIRONMENT
VIRAL INFECTIONS - rubella, mumps, and
human coxsackie virus B4, destroy βcells.
CHEMICALS - alloxan, streptozotocin,
VALCOR, cyanide producing foods (e.g.,
cassava and certain beans) toxic to β cells.
STRESS - Surgery, trauma, and stress of
situations, internal or external, may "bring
out” the disease.
OTHER FACTORS - occupation, marital
status, religion, economic status, education,
urbanization and changes in life style which
common in the lower social classes

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25. SCREENING OF DIABETES

26. URINE EXAMINATION –
commonly used but yields many
false negatives, PPV – 10-50%,
sensitivity  but specificity 
(90%), not useful for
epidemiological surveys.
BLOOD SUGARTESTING –
considered more appropriate, used
for epidemiological surveys,
random, fasting and PP sugar
done, PP sugar after 75g oral
glucose considered best either
alone or with fasting sugar.

27. RIGHT POPULATION FOR SCREENING
“HIGH RISK GROUPS”
1. those in the age group 40 and over
2. those with a family history of diabetes
3. the obese
4. women who have had a baby weighing more than 4.5
kg (or 3.5 kg in constitutionally small populations)
5. women who show excess weight gain during
pregnancy, and
6. patients with premature atherosclerosis.

28. PREVENTION OF DIABETES

29. PRIMARY PREVENTION
POPULATION STRATEGY –
• Primordial prevention
• Maintenance of normal body
weight through adoption of
healthy nutritional habits and
physical exercise.
• An adequate protein intake,
• A high intake of dietary fibre and
avoidance of sweet foods.
• Elimination of other less well
defined factors such as protein
deficiency and food toxins.
• education of patients and their
families to optimize the
effectiveness of primary health
care services.
HIGH-RISK STRATEGY –
• no special high-risk strategy for
type 1 diabetes.
• Genetic counselling may be done
but not feasible at present.
• Correction of sedentary lifestyle,
over-nutrition and obesity for
NIDDM.
• Avoidance of Alcohol, diabetogenic
drugs like oral contraceptives.
• Reduction of factors that promote
atherosclerosis, e.g., smoking, high
blood pressure, elevated
cholesterol and high triglyceride
levels.
• May be directed at target
population groups.

30. SECONDARY PREVENTION
EARLY DIAGNOSIS –
a) Proper screening
b) Routine checking of blood sugar, of urine for proteins and
ketones, of blood pressure, visual acuity and weight
should be done periodically.
c) The feet should be examined for any defective blood
circulation (Doppler ultrasound probes are advised), loss
of sensation and the health of the skin.
d) Primary health care – of utmost importance.

31. SECONDARY PREVENTION (cont.)
MANAGEMENT –
• Proper management of the diabetes is most
important to prevent complications.
• Investigations used for early diagnosis should be
done.
• Treatment is based on (a) diet alone - small balanced
meals more frequently, (b) diet and oral anti diabetic
drugs, or (c) diet and insulin.

32. SECONDARY PREVENTION (cont.)
Glycosylated haemoglobin :
• estimation at 6 monthly intervals.
• long-term index of glucose control.
• rationale: glucose in the blood is complexed to a
certain fraction of haemoglobin to an extent
proportional to the blood glucose concentration.The
percentage of such glycosylated haemoglobin reflects
the mean blood glucose levels during the red cell life-
time (i.e., about the previous 2-3 months)

33. SECONDARY PREVENTION (cont.)
Home blood glucose monitoring :
• Glucometers - immediate, reasonably accurate, capillary blood glucose
measurements
• the direct reading Haemoglukotest strips .
Self-care :
• adherence to diet and drug regimens,
• examination of his own urine
• blood glucose monitoring
• self administration of insulin,
• abstinence from alcohol,
• maintenance of optimum weight,
• attending periodic check-ups,
• recognition of symptoms associated with glycosuria and hypoglycaemia, etc.

34. TERTIARY PREVENTION
• Diabetes is major cause of disability through its complications, e.g.,
blindness, kidney failure, coronary thrombosis, gangrene of the lower
extremities, etc.
• The main objective at the tertiary level is to organize specialized clinics
(Diabetic clinics) and units capable of providing diagnostic and
management skills of a high order.
• The tertiary level should also be involved in basic, clinical and
epidemiological research.
• local and national registries for diabetics should be established.