|
World Health Organisation has laid down the following values for diagnosing Diabetes
Mellitus & differentiatillg it from Impaired Glucose Tolerance (1)
Glucose(mg/dl)
Whole Blood Plasma
Venous Capillary Venous Capillary
Diabetes
a) Fasting >120 >120 >140 >140
b) 2hrs.after >180 >200 >200 >200
glucose load
Impaired
Glucose Tolerance
a) Fasting <120 <120 <140 <140
b) 2 hrs. after 120-180 140-200 140-200 160-200
glucose load
The classification adopted by WHO(l) is as follows: Diabetes Mellitus
1. Diabetes Mellitus
i) Insulin Dependent Diabetes Mellitus (Type 1)
ii) Non-insulin Dependent Diabetes Mellitus (Type 2)
iii) Malnutrition - Related Diabetes Mellitus
iv) Other types (secondary to pancreatic, hormonal, drug induced, genetic & other
abnormalities).
2. Impaired Glucose Tolerance
3. Gestational Diabetes Mellitus
PREVALENCE : There is wide geographic variation in the prevalence of Diabetes Mellitus around the world as determined by various surveys from time to time.(2,3)
| |
Percent Prevalence |
Type |
| Fiji Indians |
13.5 |
NIDDM |
| Indonesia |
1.7 |
NIDDM |
| Iserael |
15.9 |
NIDDM |
| Malta |
7.7 |
NIDDM |
| Naauru |
24.3 |
NIDDM |
| Papua New Guinea |
0.0 |
NIDDM |
| Mexican Americans (U.S.) |
17.0 |
NIDDM |
| Pima Indians (U.S) |
25.5 |
NIDDM |
| U.S.A. |
6.9 |
NIDDM |
| North Europe |
0.211 |
DDM (in children) |
| Sweden |
0.154 |
IDDM (in children) |
| Algeria |
0.027 |
IDDM (in children) |
| Japan |
0.006 |
IDDM (in children) |
| China |
0.009 |
IDDM (in children) |
| UK Whites |
0.099 |
IDDM (in children) |
| UK Asians |
0.054 |
IDDM (in children) |
| Aragon; Spain |
6.1 |
DM |
| Alaska |
1.92 |
DM |
| Elderly Americans |
|
|
| Population (55 yrs)
(The Rotterdam study)
|
11.3 |
DM |
A well organised multi-centre study financed by ICMR showed that in 15 yrs. of age, the
overall prevalence rate for India as a whole was 1.73%. Another aspect which has been unveiled by this and other surveys is the wide difference in prevalence across the country as also between urban and rural areas, being higher in urban areas.(4)
| Place |
Urban |
Rural |
| Multicentre(1979) |
3.00 |
1.30 |
| Ahmedabad |
3.80 |
1.93 |
| Calcutta |
1.78 |
1.48 |
| Cuttack |
2.02 |
0.60 |
| Delhi |
0.95 |
1.53 |
| Pune |
1.86 |
1.10 |
| Trivandrum |
1.83 |
1.00 |
| Madurai |
0.50 |
----- |
| Tenali |
4.70 |
----- |
| Bhadran |
----- |
3.80 |
| Kudremukh |
5.00 |
----- |
| Gangavathi |
---- |
2.20 |
| Eluru |
----- |
1.60 |
| Madras |
8.20 |
2.40 |
| Kottayam |
---- |
3.87 |
Relation with age : Diabetes can start at any age. Cases are on record where diabetes
has been first diagnosed as early as 1 year 2 months or as late as 91 years. However, there is a strong positive association of age with diabetes as determined by various surveys/ (5,6)
| Place |
Percentage |
In Age Group |
| T.N. |
21 |
40 yrs. |
| Lucknow |
9.1 |
30 yrs. |
| Cuttack |
5.5 |
30 yrs. |
| Hyderabad |
3.8 |
30 yrs. |
| Madurai |
1.4 |
30 yrs. |
| Ahmedabad |
16.5 |
60 yrs. |
| Kottayam |
26.09 |
60-64 yrs. |
| France |
8.5 |
65 yrs. |
| Rotterdam |
3.8F |
|
| Study |
5.9M |
55-60 yrs. |
| |
18.9F |
85 yrs. |
| |
19.9 M |
85 yrs. |
Young diabetics are defined as those who get this affection before 25 years of age. IDDM
occurring before 15 years is classified as Juvenile Insulin Dependent Diabetes Mellitus (JIDDM). Krishnaswami C.V. et al, measured the prevalence of JIDDM in South India to be 0.01% which is twenty times lower than the reported prevalence in western countries. (7)
Relation with sex : World wide a greater male preponderance has been observed
generally. However in some areas there has been increased female prevalence. The situation in India follows the general trend world wide of increased male involvement.(4,8,9)
| Place |
Male |
Female |
| Mauritius |
12.1% |
11.7% |
| Aragon, Spain |
7.1% |
5.6% |
| Rotterdam Study |
5.9 - 19.8% |
3.8 -18.9% |
| Burkina Faso (Africa) |
64% of total diabetics |
36% of total diabetics |
| Cameroon diabetics |
62% of total |
38% of total diabetics |
| Madras Urban |
10.36% |
6.1% |
| Madras Rural |
2.7% |
2.10% |
However, in Creoles residing in Mauritius there is increased prevalence in females 13.0%
(Vs 7.7.% in males). In Sahel & Saharan countries too, there is slight increase in female prevalence.(9, 10)
RACE: Certain ethnic populations show a high prevalence of Diabetes Mellitus. Zimmet
PZ classified ethnic groups in three categories on the basis of their genetic susceptibility.
| Low |
Moderate |
High |
| White |
Africans |
American Indians |
| Eskimos |
Chinese |
Micronesians |
| Others |
Melanesians |
Polynesians |
| Japanese |
Asian |
Indians |
| |
|
Mexican Americans
Hispanics
|
The race as a risk factor is independent of environmental influences. This is proved by
the fact that migrant populations have different prevalence rates compared to natives.
Indians are considered as a high ethnic group for diabetes. This has been shown by
various studies comparing prevalence of diabetes in migrant Indians with other ethnic groups.
| Country |
Prevalence(%)
in Indains
|
Other groups |
|
| Trinidad
(1986)
|
19.5
(M) 21.6 (F)
|
Europeans4.3(M)
Africans 8.2(M)-
|
- 10.2(F)
14.8(F)
|
| Fiji (1983) |
21.9 (M)
11.0(F)
|
MelanesianS
|
3.5(M)
7.1(F)
|
|
South Africa
(1983)
|
10.4
|
Africans
Malays
|
3.6
6.6
|
|
Singapore
(1975)
|
6.1
|
Chinese
Malays
|
1.6
2.4
|
|
Coventry, UK
(1989)
|
11.2 (M)
8.9(F)
|
Europeans
|
2.8 (M)
4.3(F)
|
|
Mauritius
(1989)
|
12.4
|
Creoles
Chinese
|
10.4
11.5
|
|
Tanzania
(1989)
|
7.1
|
Africans
|
1.9
|
Heredity & genetic factors : The genetic nature of diabetes is undisputed. The association
is stronger in NIDDM than IDDM. Twin studies showed that in identical twins who developed NIDDM, concordance was approximately 90%. In IDDM it was 50%.(1)
Indians have been shown to have even increased familial aggregation of diabetes
compared with western countries. 45% of Indians compared to 38% of Europeans had positive family history of diabetes.
In Southern India, it was reported that if one parent was diabetic 36% of children would
inherit the disease and if both are diabetic the figure was 50%.(11)
Genetic markers : IDDM is HLA associated while NIDDM is not.(l) IDDM is powerfully
associated with HLA_DR3 & DR4 It is less strongly associated with HLA-B8 & B15.
Though NIDDM is not HLA associated, there are other genes which have a positive
association with it. They are:
1. Insulin gene hvr
2. Apolipoprotein D
3. Glucocorticoid
4. Glucokinase
5. Complement C4 B2.
A high prevalence of mutation in the mitochondrial gene (the 3243 & 8344 bp mutations)
have been found in Japanese diabetic patients but not in Koreans.
Obesity : It is a risk factor for NIDDM but has no role in IDDM. A longitudinal study in
Nauru showed Body Mass Index (BMI) to be a strong predictive factor for NIDDM in women but of marginal predictive nature in men.
The situation in India differs significantly from western population. A significant proportion
of Indian diabetics are non-obese. In Madras, it was found that only 14% of males and 28% of females were obese. Further about 25% of NIDDM's were lean BMI 20/m2). High waist hip ratio (WHR) was present in 46% of male (0.95) and 74% of female (0.8).(12)
Not only obesity but weight variability is also strongly associated with Diabetes.
Diet: Studies indicate that the diet of diabetics do not appear to differ from that of non-
diabetics except in quantity. A study in Sardinia, Italy showed that the type of feeding in infancy has no association with the development of IDDM. There is no protective effect of breast feeding nor do early exposure to cow's milk has any influence on the development of IDDM/ (13)
It has been found that serum magnesium and dietary magnesium were inversely
associated with fasting serum insulin and glucose.
Both over nutrition and under nutrition can cause diabetes. Over nutrition can cause
Diabetes Mellitus by resultant obesity. Undernutrition in early infancy and childhood may result in partial failure of beta cell function.
Socio-economic status : The age at diagnosis of IDDM was delayed in children from the
low income group. Around 80% were diagnosed by 17 years in household income of less than Rs. 2,000 compared to 85% in those having income of more than Rs. 2/000 per month. This may be due to the fact that children from low economic status attain puberty later due to lower nutritional status.
Marital status and parity : The prevalence is more in married females than unmarried
females (probably due to their increased weight gain with pregnancy). No such correlation was found among males.
The prevalence is also more in widows than widowers. This could be due to the fact
widows come under more stress than widowers.
Environmental factors : The environmental factors also undoubtedly play a part in
unmasking of the disease. The prevalence is more in migrant Indians compared to Indians back home. As previously described, it is more in urban areas than rural areas.
Natural disasters may also play a part. A follow-up after the Hanshin -Awaji earthquake
has showed that the diabetic control of out patients became worse after the quake/ '
Viral infections : Viral infections may trigger in immunogenetically susceptible people a sequence of events resulting in beta-cell destruction. The implicated viruses are rubella, mumps & human coxsackie virus 84.
Chemical agents : Chemical agents known to be toxic to beta-cells are alloxan,
streptozotocin, the rodenticide VALAOR, etc. A high intake of cyanide producing foods e.g. cassava and certain beans may also have toxic effect on beta-cells.
ASSOCIATION WITH HYPERTENSION: Hypertension probably causes insulin
insensitivity. In a recent Indian study 36% of the hypertensives were found to be diabetic. The finding is in agreement with those for the western population.
COMPLICATIONS
Macroangiopathy : Atherosclerosis occurs earlier in diabetics compared to general
population. Peripheral Vascular Disease (PVD) in diabetics has a prevalence of 12-15% in western countries. In India/ it is only 4.5% Gangrene is 17 times commoner in diabetics while amputation is 2-4 times more common.
Patients of PVD commonly have coexistent Coroary Artery Disease (CAD). In western
countries, the incidence of CAD in diabetics is 42-74% and female predominance. In contrast, the incidence is 6.6-33%, male predominance & later onset in India.
Clinical manifestations of CAD in diabetics involve pump failure (80-85%), sudden
arrhythmogenic death (10%) and greatly increased incidence of silent myocardial ischaemia. Ahluwalia G et al detected silent myocardial ischaemia in 50% of the diabetic patients on exercise electrocardiography and in 35% on ambulatory electrocardiography compared with 10% and 5% in non-diabetics.(15)
Cerebrovascular Disorders (CVD) in diabetics lead to stroke or multi infarct dementia. The
available data on stroke in diabetics varies widely with reference to time and place of study. But on an average the total incidence is 2-3 times in Diabetes Mellitus as compared to non-diabetics. The situation is similar in India.
The prevalence in India varies from 0.5-9.2% which is relatively high compared to west.
Diabetes has been significantly related to multiple but not single lacunar infarcts.(16)
Retinopathy: The frequency of retinopathy vary with the age of onset as well as the duration of disease, the duration having the most consistent association.
Association with duration:
In yotmg insulin taking Older patients (30 years
patients at time of diagnosis)
17% in <5years 28.8% in <5 years
97.5% in >15 years 77.8% in >15 years
Thus retinopathy appears to develop earlier in older patients. But proliferative retinopathy
is less common in older patients. Approximately 3-6% of diabetics have proliferative retinopathy. It takes an average of 15-20 years in IDDM and 10-15 years in NIDDM to develop.
The relative risk for the presence of diabetic retinopathy in smokers to those who have
never smoked is 1.21.
It is recommended that all diabetics be regularly screened for retinopathy. However in a
shady done in Barcelona it was found that 32.9% of patients were never screened for retinopathy at the primary care level.
Nephropathy : Western literature suggests approximately 35% of patients with IDDM
develop this complication. The prevalence in patients with NIDDM depends on the ethnic background varying from. 15-60%. It is highest in Pima Indians while Europeans have the lowest.
Studies in India found the complication in NIDDM to be varying from 19.7-28.5% while in
IDDM it was 7.9%. The average age at presentation was 53.01-55.9% years.(17,18)
About 21% of patients of Diabetic Nephropathy (DN) reach the end stage an average of
11.85 years after the onset of disease. The manifestation of DN occur earlier in those patients who reach the end stage.
Manifestation % age of Time to Manifestation (in yrs)
Patient Reached end stage Did not
Hypertension 85 8.47 11.36
Oedema 99.7 9.85 12.45
Proteinuria 99.7 9.87 12.96
Azotaemia 76 10.90 13.60
Five year survival rates for renal grafts are only 44% in diabetics compared to 72% in n
on-diabetics. The most common causes of death are myocardial infarction and septicemia.
Neuropathy: Diabetic neuropathy may be somatic or autonomic. In western countries a
prevalence of 59-62% has been noted clinically. When electrodiagnostic procedures are added, neuropathy could be established in up to 82% of the patients.(19)
In India Kar, calculated the prevalence of diabetic neuropathy in 58.3% of patients.(20)
Risk factors for neuropathy are:
(i) Retinopathy and nephropathy
(ii) Tall persons
(iii) Nutritional deficiency
(iv) Stress
(v) Alcohol intake
(vi) Lean persons.
However, there is no role of thiamine deficiency.
The frequency of autonomic neuropathy ranges from 28-40% in various studies. The most
common cause of death in patients with autonomic neuropathy was renal failure followed by sudden unexpected cardiorespiratory arrest.
Cancers : Diabetic patients have an increased incidence of endometrial, breast and pancreatic cancers.
Gall Stones : An altered glucose metabolism may increase the risk of developing cholelithiasis in certain subjects.
Glaucoma & ocular hypertension : The blue mountains eye study in Australia found that Glaucoma prevalence was increased in people with diabetes (5.5% Vs 2.8%). Ocular hypertension was also more common in diabetics (6.7% Vs 3.5%).
Depression : There is an increase prevalence of depression in diabetics varying from 8.5% to 27.3%.
Accidents : It has been shown that diabetic truck drivers have more accidents than drivers in good health.
Mortality : Diabetes is one of the leading cause of death in the developed countries. In the USA, it is the fourth leading cause of death. The following table shows the mortality rates as a result of diabetes across the world.
| Country |
Rate of diabetes mortality (per 100,000) |
| Trinidad |
48.6 |
| Barbados |
48.2 |
| Belgium |
33.3 |
| Greece |
30.8 |
| USA |
14.8 |
| France |
13,1 |
| England |
9.3 |
| Sri Lanka |
9.2 |
| Japan |
7.1 |
REFERENCES
1. WHO Techn Rep Ser 1985; No.727.
2. King H, Reaven M, WHO Ad Hoc Diabetes Reporting Group. Globai estimates for
prevalence of diabetes mellitus and IGT in adults. Diabetes Care 1993; 16: 157- 177.
3. Diabetes Epidemiology Research International Group. Geographic pattern of
childhood insulin dependent diabetes mellitus. Diabetes 1988; 37: 1113-1119.
4. Ramchandran A, Snehlata C, Dharmaraj D, Vishwanathan M. Prevalence of glucose |
