A study, conducted by researchers associated with the Division of Diabetes Translation within the Centers for Disease Control and Prevention (CDC), was recently published in the Journal of the American Medical Association (JAMA), and it addresses the prevalence and incidence of diabetes in the U.S.
From 1980 to 2012, the researchers investigated the prevalence and incidence trends of diagnosed Types 1 and 2 diabetes mellitus. The study was performed by analyzing data from 649,969 adults between the ages of 20 and 79 from the National Health Interview Survey over the course of 32 years. The sample included demographic details such as age, sex, education level and race/ethnicity.
With the rise of fast food restaurants and the incorporation of various artificial ingredients and processed foods, obesity and diabetes rates have risen dramatically in the U.S. Over the course of the 32-year study, the authors found that both the prevalence and the incidence of diabetes have risen sharply since the study’s inception, but recent reports analyzed by the study indicate that the growth in obesity rates is beginning to plateau, which corresponds with a deceleration in the rate of diabetes diagnoses.
The study defined prevalence of diabetes as the number of participants diagnosed with the disease per 100 participants. Meanwhile, those diagnosed within the last 12 months of the annual survey were reported as incidence cases. The incidence of diabetes refers to the number of participants at risk per 1,000 persons per year. Both of these categories showed increasing trends for the majority of the study.
Age was one demographic factor that showed a particularly strong upward trend in diabetes prevalence as the age of the participant increased. While younger age groups maintained a low level of prevalence for diabetes, older age divisions, or those above 44 years old, showed dramatic increases in prevalence of diabetes. The incidence showed a similar trend with the exception of the top two age groups, 44 to 64 years old and 64 to 79 years old. While the highest rate of incidence occurred in the 64 to 79 cohort, in the last 12 years of the study the second age group rose to a nearly equal level but plateaued at 12 persons per 1,000.
Sex differences showed a trend in which men displayed a higher prevalence of diabetes, specifically from 2000 to 2012. The prevalence of diagnosed diabetes in women, on the other hand, appeared to plateau over the last two years of the study. In terms of gender, however, the incidence of diagnosed diabetes tells a difference story. Men and women had approximately equal, and increasing, risk for diabetes from 1980 to 2006, but between 2007 and 2008 the incidence of male diagnoses declined sharply. The authors of the study provided no possible explanation for this discrepancy.
Education levels played an astonishing role in both the prevalence and the incidence of diabetes. The study found that individuals with at least a high school degree had lower levels of both prevalence and incidence for the disease. While the trend for both categories steadily increased for the duration of the study, one sub-group remained clearly on top. Possessing no high school degree coincided with both a higher prevalence and incidence of diabetes.
The last demographic subpopulation was race/ethnicity of the participants. The study divided the participants into three groups: non-Hispanic white, non-Hispanic black and Hispanic. For both prevalence and incidence, the group with the highest value and increasing trend was the non-Hispanic black group. The Hispanic group followed suit with slightly lower values in both categories. In both prevalence and incidence, these groups shared very close values; however, in recent years, the Hispanic group surpassed the non-Hispanic black group in the incidence of diabetes, reaching around 12 out of 1,000 persons per year. In both cases of incidence and prevalence, non-Hispanic whites maintained a much lower value but still strongly indicated an upward trend.
In the end, the researchers unsurprisingly concluded that in the U.S. from 1980 to 2012, there was a strong increase in both prevalence and incidence of diabetes. The strongest of these growths occurred in the 1990s. This sudden growth in incidence may have been caused by a change in the criteria needed to be considered as having diabetes; however, it is unlikely that this was the only factor affecting incidence at the time. Furthermore, the study reached the positive conclusion that both prevalence and incidence are plateauing in the U.S. However, this trend is not represented equally in all population subgroups. Those of non-Hispanic black and Hispanic ethnicities and those with less education continue to experience an upward trend in the incidence and prevalence of diagnosed diabetes.