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Mexicans have Increased Risk for Mortality If Diagnosed with Diabetes

Study shows death rate more than five times higher than in those without the disease.

Mexicans who have diabetes are at high risk for all-cause mortality, have markedly poor glucose control, and are under-treated for cardiovascular risk factors, according to a large prospective study.

UK researchers used a cohort of almost 150,000 residents in Mexico City and found that 30% of all deaths were attributed to the excess disease-related mortality, with the largest absolute excess mortality risks coming from cardiac disease, infection and renal disease.

The findings stand in contrast to those from a recent meta-analysis of studies conducted in high-income countries, which found that diabetes less than doubled the rate of death from any cause.

Jonathan Emberson, PhD, of Oxford University in England, and colleagues reported that the all-cause mortality rate was more than five times higher in Mexicans ages 35 to 59 with diabetes than in their non-diabetic counterparts.

The mean glycated hemoglobin level in Mexicans with diabetes was 9.0%, and more than a third had glycated hemoglobin levels higher than 10.0%. Previous studies in affluent countries have shown only about 5% of people with diabetes having levels higher than 10.0%, the researchers said.

Approximately 80% of Mexicans with diabetes were on some type of antidiabetes medication, but only 23% were on blood pressure medication and just 1% were receiving lipid-lowering drugs, the study found.

Emberson added in his presentation that, “In countries such as Mexico, where obesity and diabetes are common and blood sugar control is poor, the most important need is for proper medical management of people who already have diabetes, not just with drugs to control their blood sugar, but also with other widely available, effective, and inexpensive drugs that reduce risk in other ways (e.g. by reducing blood pressure and blood cholesterol).”

In addition to their relevance to Mexico, the results are relevant to many other populations worldwide, including many millions of U.S. Mexican-Americans, among whom the prevalence of diabetes is twice as high as that among U.S. non-Hispanic white persons and glycemic control is worse.

Diagnoses of diabetes were self-reported. Among participants ages 35 to 39, the prevalence of diabetes was 3%, but it rose sharply to more than 20% in those 60 or older.

The prospective study included approximately 150,000 residents of Mexico City age 35 or older. From 1998 through 2004, the researchers visited households; took blood samples for glycated hemoglobin measurements; gathered socioeconomic and lifestyle information; and took clinical measurements such as height, weight, and blood pressure.

Deaths were tracked up to January 1, 2004, through electronic linkage to the death registry in Mexico City. The researchers evaluated the relationship between a diagnosis of diabetes and mortality with a Cox regression model that excluded individuals with chronic diseases such as kidney disease, heart disease, and cancer. The rate ratios for death were adjusted for factors such as age, education level, and smoking.

In participants reporting a diagnosis of diabetes, the excess mortality associated with the disease accounted for 30% of all deaths. The largest absolute excess risks of death were from renal disease, cardiac disease, and infection. In addition, acute diabetic crises accounted for 8% of all deaths among participants with diabetes, Emberson and colleagues reported.

The relative difference in death rates between people with diabetes and people without tapered off with age. For people with diabetes ages 60 to 74, the rate ratio was 3.1, and for those 75 to 84, the rate ratio was 1.9. “This is consistent with previous studies that have looked at the effect of diabetes in high-income countries,” Emberson added.

One limitation of the study was that it did not check self-reports of medically diagnosed diabetes against medical records. However, “the glycated hemoglobin findings (and high rate ratios for deaths from any cause) suggest that such reports were reasonably reliable, with generally normal glycated hemoglobin levels among persons who reported no diabetes,” the investigators said.

The findings highlight the need for national prevention programs in middle-income and low-income countries that target the underlying causes of diabetes, especially obesity.

Practice Pearls:

  • Mexican patients with diabetes are at high risk for all-cause mortality, have markedly poor glucose control, and are under-treated for cardiovascular risk factors.
  • Note that all-cause mortality was more than five times higher in Mexicans ages 35 to 59 with diabetes than in their non-diabetes counterparts, while a recent meta-analysis of high-income countries found that diabetes less than doubled the rate of death from any cause.
  • There is a need for national prevention programs in middle-income and low-income countries that target the underlying causes of diabetes, especially obesity.

Reference:

Alegre-Diaz J, et al “Diabetes and cause-specific mortality in Mexico City” N Engl J Med 2016; 375: 1961-71.