Distribution and Incidence
Many methods have been used to ascertain the prevalence of DM. Methods have ranged from telephone and household surveys, reviews of hospital records, to screenings using urine and blood determinations of glucose concentrations.
Because of its acute onset and obvious symptoms, type I diabetes is readily identified and, therefore, permits a more accurate picture of worldwide prevalence. Data from the 1960s through the 1980s indicated that populations with prevalence rates of insulin-dependent DM of at least 1.0 per 1,000 include Finland, Sweden, the United States, England, France, and Australia. Intermediate prevalence rates of 0.5 to 0.9 per 1,000 are found in Scotland, Switzerland, East Germany, and Denmark. Rates below 0.5 per 1,000 occur in Italy, Japan, India, Taiwan, Vietnam, Libya, China, the South Pacific, Ethiopia, and the West Indies. Type II DM is a chronic disease with generalized symptoms; therefore, many cases are not diagnosed. The American Diabetes Association estimates that 40 to 50 percent of Americans with type II DM have not been diagnosed. On the whole, however, rates of type II do appear to be increasing in developing nations. Table VIII.34.2 lists the prevalence rates of diabetes in 1960-85 for 28 countries.Most surveys on the annual incidence of insulindependent DM include individuals in the age range 0 to 14 or 0 to 16 years. High rates of 15 to 30 per 100,000 are reported for Finland, Sweden, Scotland, Norway, and Yugoslavia; intermediate rates of 10 to 14.9 per 100,000 for Denmark, the United States, the Netherlands, and New Zealand; and low rates of 0 to 9.9 per 100,000 for Israel, Japan, Great Britain, France, Canada, India, Italy, Ghana, and Nigeria. The incidence data from Sweden also indicate an increase in the number of cases of type I diabetes from 19.6 per 100,000 (1970-5) to 24.9 per 100,000 (1980-2) for children age 0 to 14 years.
Generally, investigators have been cautious in interpreting the rates as an actual increase in the incidence of insulin-dependent DM. Prevalence rates continue to Table VIII.34.2. Prevalence of diagnosed diabetes in representative populations, 1960—85| Country | Population description | Rate (%) |
| United States | American Indians (multitribal adults) | 10.0 |
| United States | >20 | 6.2 |
| Canada | all ages | 2.0 |
| Argentina | adults | 2.9 |
| Costa Rica | >30 years | 5.4 |
| El Salvador | >30 years | 3.2 |
| Guatemala | >30 years | 4.2 |
| Jamaica | ≤25 years | 8.0 |
| Panama | >30 years | 2.5 |
| Trinidad | ≥20 years | 4.5 |
| Uruguay | >30 years | 6.9 |
| Venezuela | >30 years | 7.0 |
| England | all ages | 0.6 |
| Germany | all ages | 1.3 |
| Italy | all ages | 2.5 |
| Scotland | all ages | 0.6 |
| Spain | all ages | 1.3 |
| Sweden | all ages | 2.0 |
| Yugoslavia | ≥15 years | 1.1 |
| Australia | adults | 0.9 |
| India | rural ≥ 15 years | 1.3 |
| urban≥15 years | 3.0 | |
| Japan | all ages | 0.4 |
| Malaysia | ≥30 years | 4.2 |
| Singapore | ≥15 years | 6.1 |
| South Africa | whites≥15 years | 3.6 |
| South Africa | Bantu≥15 years | 4.1 |
| Zambia | urban all ages | 0.3 |
| Fiji | ≥20 years | 11.8 |
| Samoa | urban≥20 years | 10.1 |
| Tonga | urban≥20 years | 9.9 |
Sources: Hamman (1983), Bennett (1983), Taylor and Zimmet (1983), West (1978: 132-4).
rise because of increased longevity of individuals with type I diabetes.
The incidence rates for type II diabetes vary extensively by age and sex for different populations. In general, the incidence increases with age for both males and females until the sixth or seventh decade of life. The incidence of diabetes in the United States, or the number of newly diagnosed cases per 10,000 population per year, has risen 7-fold since the first large-scale survey in 1935—6, when the rate was 3.8 per 10,000. The highest incidence was reported in 1973 (29.7 per 10,000) and the information from 1979 to 1981 reveals a rate of 22.7 per 10,000. Approximately 95 percent of these cases are type II diabetes.
Incidence rates of greater than 200 per 100,000 population of adults or total population are found in the United States, Israel, Finland, England, Denmark, Saudi Arabia, the South Pacific islands, and Australia. Intermediate rates between 100 and 200 per 100,000 population per year have been found in Scotland, Germany, Spain, Yugoslavia, Czechoslovakia, and Romania, and lower rates have been found in Canada, India, Southeast Asia, and some African countries.