Diabetes: CVD Deaths Drop, but More Kids Being Diagnosed

Miriam E. Tucker

April 13, 2017

New diabetes statistics include both good and bad news. Deaths from cardiovascular disease (CVD) among people with type 1 and type 2 diabetes are declining, but the rates remain high. Meanwhile, increasing numbers of children and adolescents are being diagnosed with both diabetes types.

The findings come from two studies published online April 12 in the New England Journal of Medicine. In one, Aidin Rawshani, MD, of the University of Gothenburg, Sweden, and colleagues report that in Sweden from 1998 through 2014, both mortality and cardiovascular events declined substantially among people with diabetes. However, the decline was less among those with type 2 diabetes than among control persons, and the event rates for all outcomes studied remained significantly higher overall among patients with diabetes, compared with the general population.

In the other study, Elizabeth J Mayer-Davis, PhD, of the University of North Carolina, Chapel Hill, and colleagues found that the incidences of both type 1 and type 2 diabetes among persons aged 0 to 19 years increased significantly in the United States between 2002 and 2012. There was a particularly dramatic increase in type 1 diabetes among youths of minority racial and ethnic groups.

The type 1 diabetes finding, Dr Mayer-Davis and colleagues write, "suggests a growing disease burden that will not be shared equally. Studies have shown substantial differences among racial and ethnic groups in the methods of treatment and in clinical outcomes, as well as barriers associated with processes and quality of care."

In an editorial that accompanies the two articles, NEJM deputy editors Julie R Ingelfinger, MD, and John A Jarcho, MD, point out that the two studies together paint a concerning picture. "The incidence of diabetes is increasing among young persons....As a consequence of this trend and of the aging and growth of the population, even though mortality and the rate of cardiovascular disease are decreasing among persons with diabetes, the overall adverse effect of diabetes on public health is actually increasing."

CVD Rates Down

For the study on CVD and mortality rates, Dr Rawshani and colleagues identified 36,869 patients with type 1 diabetes and 457,473 with type 2 diabetes who were included in the Swedish National Diabetes Register between 1998 and 2012 and who were followed through 2014. Each patient was matched by age, sex, and county with a randomly selected adult from the general population. Mean duration of follow-up was 11.2 years for patients with type 1 diabetes and 6.5 years for those with type 2 diabetes.

For type 1 diabetes, the all-cause mortality rate declined by 29% in the patients vs 23% in the matched population. Among patients with type 2 diabetes, the decline for all-cause mortality was 21%, compared with 31% among the matched population (P < .001).

Deaths due to CVD dropped by 42% in the type 1 diabetes group and by 38% among the matched population, which was not a statistically significant difference.

For patients with type 2, deaths due to CVD dropped by 46%; the reduction among the control participants was 50% (P = .004).

Hospitalizations for CVD dropped by 36% among the type 1 diabetes patients and by 44% among those with type 2 diabetes. For both groups, the declines were significantly greater than those seen for the respective matched control groups.

Dr Rawshani and colleagues say that the changes seen in the study most likely reflect a combination of advances, including increasing emphasis on integrated care of patients with chronic disease, improved patient education in disease management, and advancements in clinical decision-making support. Advances in revascularization and an increase in the use of glucose-monitoring systems may also have played a role.

"Perhaps most important, improved management of risk factors such as hypertension, elevated levels of LDL cholesterol and glycated hemoglobin, and macroalbuminuria, and the associated higher frequency of treatment with statins and antihypertensive medications have transformed cardiovascular risk reduction."

Diabetes Rising in Youth

For the study on diabetes rates in youths, Dr Mayer-Davis and colleagues analyzed data from surveillance networks from 2002 through 2012. They identified 11,245 patients aged 0 to 19 years who had been diagnosed with type 1 diabetes and 2846 youths aged 10 to 19 years with type 2 diabetes from denominators of 54,239,600 and 28,029,000 person-years, respectively.

After adjustment for age, sex, and race/ethnic group, there was a significant 1.8% relative annual increase in the incidence of type 1 diabetes (P < .001). Significant increases were seen in all age groups except those aged 0 to 4 years and also among both boys and girls and in each racial/ethnic group except Asian or Pacific Islanders and Native Americans.

The adjusted incidence of type 1 diabetes increased significantly more among Hispanic youths (annual increase, 4.2%) than among non-Hispanic white youths (annual increase, 1.2%; P < .001).

The adjusted annual relative increase in the incidence of type 2 diabetes was 4.8%.

Pairwise comparisons of adjusted annual increases showed that the increases were significantly smaller for non-Hispanic whites (0.6%) than for blacks (6.3%), Hispanics (3.1%), Asians or Pacific Islanders (8.5%), and Native Americans (8.9%: P < .05 for all comparisons).

"These findings highlight the critical need to identify approaches to reduce disparities among racial and ethnic groups," Dr Mayer-Davis and colleagues say.

Dr Ingelfinger and Dr Jarcho write, "Although it is not surprising that the incidence of type 2 diabetes among youths is increasing, the differing rates among racial and ethnic groups is somewhat unexpected. The authors note that some subgroups of youths in the United States have had a significant increase in the prevalence of obesity, which may be a contributing factor. Of even more concern is the fact that the incidence of type 1 diabetes appears to be increasing, with apparent disparities among ethnic groups that are not likely to be explained by the obesity epidemic."

The editors conclude, "It is clear that we are far from controlling the negative effects of diabetes on health worldwide. As the prevalence increases, we clearly need new approaches to reduce the burden of this disease on public health."

The CVD study was supported by grants from the Swedish Association of Local Authorities and Regions, the Swedish State, Region Västra Götaland, the Swedish Diabetes Foundation, the Swedish Heart and Lung Foundation, the Swedish Research Council, Diabetes Wellness Sweden, and the Swedish Council for Health, Working Life, and Welfare. The youth study was supported by a grant from the National Institute of Diabetes and Digestive and Kidney Diseases, the National Institutes of Health, and by the US Centers for Disease Control and Prevention. Dr Rawshani and Dr Mayer Davis have disclosed no relevant financial relationships. Dr Ingelfinger and Dr Jarcho are NEJM employees.

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N Engl J Med. Published online April 12, 2017. Rawshani et al abstract, Mayer-Davis et al abstract, Editorial

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