Diabetes Increases Stroke Risk, Particularly in Under 65s

May 06, 2013

Patients with diabetes remain at greatly increased risk for ischemic stroke at all ages, but especially in the under-65 age group, a new study shows.

"Our results suggest that diabetics aged under 65 have up to a 12-fold increased risk of stroke compared to people of a similar age who do not have diabetes," lead investigator Jane C. Khoury, PhD, Cincinnati Children's Hospital Medical Center, Ohio, commented to Medscape Medical News. "In the over 65s, there was still an increase in stroke of about 2- to 3-fold in diabetic patients."

Dr. Khoury suggested that the reason for the larger increase in younger patients is that these individuals do not have as many other risk factors for stroke, so the presence of diabetes makes a big difference. "By the time patients get to their 70s, more other risk factors come into play so the individual effect of diabetes may not be so great," she added.

The data also suggest a race difference, with evidence of higher ischemic stroke risk in whites than blacks conferred by diabetes at almost all ages.

Noting that diabetes has previously been shown to be an important risk factor associated with poor post-stroke outcomes and disability, the researchers point out that the higher rates of stroke in patients with diabetes, especially in younger patients, may be associated with a higher burden of disability, productive life-years lost, and higher cost to society.

Dr. Khoury said her take-home message is: "We need to look out for patients susceptible to stroke and treat their risk factors. Our data show that diabetes is a very important preventable ischemic stroke risk factor. We need to make sure diabetics are well monitored, especially younger diabetics, and any other risk factors for stroke, such as hypertension, smoking, and AF [atrial fibrillation], are corrected in these patients. And this is another reason to be vigilant on diabetic control."

The population study was published online April 25 in Stroke.

Increasing Prevalence of Diabetes

For this study, the researchers focused on the epidemiology of stroke in the Greater Cincinnati Northern Kentucky region at various time periods. The current analysis looked at first ischemic strokes among black and white residents of the area in diabetic patients vs patients without diabetes for three 1-year periods: (1) mid-1993 to mid-1994, (2) 1999, and (3) 2005. Incidence rates were adjusted for sex, race, and age, as appropriate, to the 2000 US population.

Results showed that 28% those sustaining a first ischemic stroke in 1993-1994 had diabetes, compared with 29% in 1999 and 33% in 2005. "Our data highlight the increasing prevalence of diabetes mellitus among stroke patients over time in line with the epidemic of diabetes mellitus seen in the general population," the authors write.

The data also show an excess risk for stroke in diabetic patients of any age in both whites and blacks. However, the excess stroke risk associated with diabetes appears to be decreasing over time in the black population, whereas it is remaining stable among whites.

Age-specific risk ratios by race also show a significant decrease over time in the black population older than age 65 years but not for those under 65 years. In the white population, those younger than 65 appear to have a 12- to 14-fold increase in stroke incidence if they have diabetes; the excess risk is less than 3 in the older age group but does not change significantly over time in either age group.

Table 1. Risk Ratios for Ischemic Stroke in White Patients With Diabetes vs No Diabetes

Group 1993-1994 1999 2005
All ages 3.8 4.0 3.8
<65 y 12.4 14.2 12.0
≥65 y 2.8 2.5 2.7



Table 2. Risk Ratios for Ischemic Stroke in Black Patients With Diabetes vs No Diabetes

Group 1993-1994 1999 2005
All ages 5.6 2.8 3.2
<65 y 8.4 9.8 5.2
≥65 y 5.9 1.2 2.1


Dr. Khoury said the race differences are not understood and require further study.

This study was funded by the National Institutes of Health, National Institute of Neurological Disorders and Stroke. Dr. Khoury and several coauthors receive research support from the National Institutes of Health.

Stroke. Published online April 25, 2013. Abstract