A Review Of Ethnic Differences In Risk Factors For Diabetic Foot Ulcers

By Caroline A. Abbott, PhD, and Carine van Schie, PhD

Research in recent years has shown distinct ethnic differences in the prevalence of diabetic complications, including amputation and more recently, foot ulceration. Although the etiology of the diabetic complications among different ethnic groups is not completely understood, preliminary data has highlighted some interesting variations in the presentation of these complications.
Projections of diabetes prevalence indicate the number of people with type 2 diabetes worldwide is set to double over a 25-year period.1 This epidemic of diabetes is due to an aging and increasingly obese population. These factors will particularly affect migrant ethnic populations, given the higher prevalance of obesity and the fact that the cohort of first generation migrants is just attaining retirement age.2,3
Migrant populations of African Caribbean and South Asian descent in the United Kingdom have a prevalence of type 2 diabetes which is three- and four-fold higher respectively than in the general population.2,3 This finding is similar to ethnic differences observed in the United States and other parts of the developed world.4,5
Work from our own and other groups indicates that rates of diabetes complications affecting the lower limb also appear to differ by ethnicity.
Diabetes-Related Amputations: What The Research Reveals
A few studies have described ethnic differences in diabetes-related amputation. Data from the U.S. shows a two- to three-fold elevation in risk for African Americans compared with White Americans.6,7 It’s possible this increased risk may be linked to inequalities in access to health care in the U.S., plus socioeconomic and environmental factors, such as education and smoking.8
In the U.K., paradoxically, amputation risk is actually lower in diabetic African Caribbeans and the risk is reduced by about two-thirds in African Caribbeans in comparison to Europeans.
Low rates of smoking among African Caribbeans could account for part of this, but certainly, the lower prevalence of peripheral vascular disease and neuropathy in this ethnic group were the other key factors accounting for the low rate of diabetes-related amputation in African Caribbean men.
Indeed, the rate of diabetes-related amputation in migrant South Asians (Indian, Pakistani, Bangladeshi origin) living in the U.K. is just one-quarter that of the Caucasian Europeans.10,11 In a very recent population-based case control study of ethnic variations in type 2 diabetes-related amputation risk in Greater Manchester, U.K., the reduced South Asian amputation rate was mostly explained by low rates of PVD and neuropathy, partly associated with low rates of smoking.11
What The Studies Say About Differences In Foot Ulcers
To date, there are few population-based studies of ethnic differences in foot ulcer rates. Existing reports consistently show that foot ulcer rates for diabetic patients of South Asian origin are lower than those for White Europeans. Indeed, lower rates of foot ulceration have been demonstrated for South Asian patients with diabetes compared to White Europeans foot ulcers were twice as prevalent among White European diabetic patients (5.5 percent) compared to their Asian counterparts (2.7 percent).12,13
We have also examined ethnic rates in the Northwest Diabetes Foot Care Study (our population-based investigation of diabetes-related foot problems in the U.K.), in which we screened 9,710 diabetic patients as part of a standardized diabetes footcare and education service in the community.14 The Northwest region of the U.K. has a relatively high proportion of South Asian migrants. The prevalence of past/present foot ulcers in South Asian diabetic patients was only 1.5 percent, significantly lower than the 5.2 percent rate for Caucasian European patients with the same access to healthcare.
The explanation for this data is not entirely clear. The U.K. Prospective Diabetes Study XII (UKPDS) has demonstrated that fewer newly diagnosed Asian and Black diabetic patients have abnormal vibration perception threshold compared to their Caucasian European counterparts. This indicates that ethnic minorities have a lower prevalence of neuropathy, which is a major risk factor for foot ulceration.15 We have confirmed this lower prevalence of neuropathy in South Asian and African Caribbean populations, using vibration and temperature sensation testing for diagnosis.16

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