Study: Black People No Greater Predisposition to Diabetes

Geschatte leestijd: 6 minuten The title may not sound very positive, but the conclusion can be encouraging. If a higher weight is the only reason why black Americans have diabetes more often than others, there is more that can be done. In theory, at least. In practice, there is a reason for the higher weight.

“Blame it on African genes”

When I have to admit to someone again that I actually do nothing for a low body fat percentage, the reaction is often: “Blame it on the African genes”. These “African genes” often fit a number of stereotypes such as “lean”, “muscular”, “well-endowed”, and “good dancer”. Personally, I can say that such a stereotype for “the African” is not accurate. After all, I’m a terrible dancer and I find it unfair to blame only that lesser trait on my Dutch genes. But statistically, a number of other stereotypes don’t hold up either (although Nigeria, according to some, does indeed fall in the zone for the greatest average penis length) [1]. I have no idea about the supposed big buttocks of women. If that is demonstrable in numbers, it wouldn’t surprise me, for the same reason that the image of “lean” African genes is becoming increasingly inaccurate. Their average weight is increasing more rapidly. At least in the case of the U.S., where black people apparently have gained weight more quickly than white people.

Dark-skinned people more likely to have diabetes

It is a well-known fact that people with darker skin tones are more likely to have diabetes. The cause for this is attributed to both genetic and environmental factors. As we read on the website of the Diabetes Fund [2]:

People of Surinamese-Hindustani, Turkish, and Moroccan descent are more prone to diabetes, according to research.

A link is also provided to a source (‘kijkopdiabetes.nl’) although I cannot find any studies there. Instead, I found the following text [3]:

Research has shown that Surinamese people in the Netherlands, like other migrant groups, are at greater risk of getting diabetes. Sensitivity to the disease plays a role, but also overweight due to a different lifestyle is an important cause. Type 2 diabetes mainly occurs in people over 45, but in Hindu people, the risk age is already at 35.

These conclusions might come from the HELIUS study which revealed that population groups with a migration background have a higher prevalence of diabetes [5]. In that study, data from 202 native Dutch, 206 Surinamese-Hindustanis, 205 Surinamese of African descent, 215 Turks, and 213 Moroccans were analyzed. A similar conclusion is made in the U.S. regarding the African-American population. In that group too, a higher prevalence of diabetes is observed compared to, for example, the white population in America. This is normally attributed to a combination of genetic and environmental factors. However, recent research shows that only environmental factors explain these higher figures and that black people do not actually have a higher, biological predisposition for diabetes. Worse conditions would lead to poorer eating habits and less exercise. As a result, black people in the U.S. have gained weight more quickly than the white population. According to the study, this difference in overweight is enough to explain the difference in diabetes prevalence.

Higher weight the only explanation

The research from Northwestern University comes to the surprising conclusion that black and white people have an equal chance of having diabetes when all biological risk factors are taken into account [3]. The findings contradict the long-standing belief that there must be an (unexplained) genetic reason why middle-aged black Americans have diabetes twice as often as white Americans. The study was published last month in JAMA (The Journal of the American Medical Association) [4].

Obesity is driving these differences. The findings surprised us, because for the past 20 years there was a narrative that there must be something we haven’t found that was causing this higher rate. Mercedes Carnethon, associate professor preventive medicine, Northwestern University Feinberg School of Medicine

Previous studies that did show higher diabetes rates in the black population took into account factors such as overweight and socioeconomic status. The researchers at Northwestern University went further by considering more biological factors such as BMI, waist fat, blood sugar, lipids, blood pressure, and lung function. When all these factors were adjusted for, the likelihood of diabetes was the same between black women and white women. If not corrected for these factors, the likelihood of black women having diabetes was three times higher.

Blacks gained more weight over time. It was the accumulation of this and other risk factors that eliminated the so-called mysterious cause of the disparity.

The reason why other studies would come to the wrong conclusion, despite adjusting for factors such as overweight, diet, and physical activity, is that these were measured at one moment. These factors can change over time and these changes can vary in size by race, according to the researchers at Northwestern. The importance of the study would therefore be significant, especially in the U.S. where diabetes is becoming increasingly common in young black people between the ages of 10 and 19. The researchers refer in this context to earlier studies showing that in this group, the number of people with diabetes increases annually by 6 percent. In the white population of the same age, this remained constant.

“Just” work on the overweight

So, while the good news is that black people do not have an inherent increased risk of diabetes, it does not mean that the solution is easy. All the circumstances that cause some socio-economic and cultural groups to have less access to healthy food and opportunities for more exercise are not easy to change. The research shows that it makes little sense to further investigate biological differences that explain the higher numbers of diabetes patients in black people. It shows that the usual efforts to bring people to a healthier lifestyle and weight can also meet the same goal in this target group to reduce the risk of diabetes to the same extent. However, these efforts must be successful, and that proves to be more difficult in some groups.

Overweight or different weight?

In addition to circumstances that make it difficult for you to achieve a healthy weight, you can also consider a different definition for ‘a healthy weight’. The difference in weight gain was greater between black and white women than between black and white men in the Northwestern study. This raised the question for me to what extent the ideal of beauty can play a role. For example, what about the cliché that black men like a big butt, which logically would be related to a higher weight? According to a 2007 study, that cliché turned out not to be true [6]. For clarity, “Baby Got Back” by Sir Mix-a-lot was released in 1992. According to the study from the American University in Washington, black men do not necessarily like a big butt, but a well-shaped one. In the study, black men attached more importance to a low waist-to-hip ratio than white men. A ‘well-shaped butt’ can result from either a narrow waist with ‘normal’ buttocks, or a larger waist with larger buttocks. Black men preferred the first option. Although they attached more importance to the waist-to-hip ratio, they, like white men, preferred women with a normal or low weight. It may be an example of independent ladies because various studies show that African-American women generally worry much less about their weight than white women [6,7]. Studies, for example, show that African-American women see a slightly higher weight in their beauty ideal [8,9]. Other examples are studies showing that they worry less about their diet, weight fluctuations, and body fat [10]. That has many positive aspects, of course. According to a 2008 study, African-American women are less likely to associate ‘the beauty ideal’ with themselves [8]. So, less pressure to meet a certain ideal. Moreover, it turned out that black women with a higher weight were more satisfied with specific body parts [11]. So, there are different paths that can lead to overweight. The familiar cycle of eating – feeling guilty – eating more might be less expected among black (American) women. On the other hand, one could wonder to what extent it is an advantage if you don’t worry about your weight while your doctor may think differently.

References

1. targetmap.com/viewer.aspx?reportId=42254
2. diabetesfonds.nl/over-diabetes/heb-ik-diabetes/wie-loopt-meer-risico-op-diabetes
3. kijkopdiabetes.nl/publiek/index.php/info-voor-surinamers
4. Michael P. Bancks, Kiarri Kershaw, April P. Carson, Penny Gordon-Larsen, Pamela J. Schreiner, Mercedes R. Carnethon. Association of Modifiable Risk Factors in Young Adulthood With Racial Disparity in Incident Type 2 Diabetes During Middle Adulthood. JAMA, 2017; 318 (24): 2457 DOI: 10.1001/jama.2017.19546
5. M Muilwijk, C Celis-Morales, M Nicolaou, MB Snijder, JMR Gill, IGM van Valkengoed. Plasma cholesteryl ester fatty acids do not mediate the association of ethnicity with type 2 diabetes: results from the HELIUS study. Mol Nutr Food Res 2017 Oct 5 [Epub ahead of print].
6. Freedman REK, Carter MM, Sbrocco T, Gray JJ. Do men hold African-American and Caucasian women to different standards of beauty? Eating behaviors. 2007;8(3):319-333. doi:10.1016/j.eatbeh.2006.11.008.
7. Cultural body shape ideals and eating disorder symptoms among White, Latina, and Black college women. Gordon KH, Castro Y, Sitnikov L, Holm-Denoma JM Cultur Divers Ethnic Minor Psychol. 2010 Apr; 16(2):135-43.
8. Bulimic symptoms and body image dissatisfaction in college women: more affected by climate or race? Lokken KL, Worthy SL, Ferraro FR, Attmann J J Psychol. 2008 Jul; 142(4):386-94.
9. Cash TF, Pruzinsky T. Body Image: A handbook of theory, research, and clinical practice. New York, NY: Guilford Press; 2002
10. Rucker CE, Cash TF. Body image, body-size perceptions, and eating behaviors among African American and White college women. International Journal of Eating Disorders. 1992;12:291–299.
11. Falconer JW, Neville HA. African American college women’s body image: An examination of body mass, African self-consciousness, and skin color satisfaction. Psychology of Women Quarterly. 2000;24:236–243.