Racial Disparities in the Pathogenesis of Type 2 Diabetes and its Subtypes in the African Diaspora: A New Paradigm

An Intersectional Approach to Examining Breast Cancer Screening among Subpopulations of Black Women in the United States

This study examines breast cancer screening behavior among subpopulations of Black women in the United States. Binary logistic regression was used to analyze breast cancer screening among a nationally-representative sample (n = 9,783) of Black women-US-born, non-US-born Caribbean, and non-US-born African-from the 2011-2017 National Health Interview Survey dataset. Non-US-born African Black women were less likely to have breast cancer screening, compared to US-born Black women. Among non-US-born Black women, non-US-born Caribbean Black women were more likely to have had breast cancer screening. Differential healthcare access associated with nativity differences among Black women can be informing their breast cancer screening behaviors. Efforts to improve breast cancer outcomes among Black women can benefit from interventions that account for differential access to healthcare and breast cancer screening behaviors among subgroups of Black women.

Changes in the Microbiota and their Roles in Patients with Type 2 Diabetes Mellitus

An association between type 2 diabetes mellitus (T2DM) and gut microbiota is well established, but the results of related studies are inconsistent. The purpose of this investigation is to elucidate the characteristics of the gut microbiota in T2DM and non-diabetic subjects. Forty-five subjects were recruited for this study, including 29 T2DM patients and 16 non-diabetic subjects. Biochemical parameters, including body mass index (BMI), fasting plasma glucose (FPG), serum total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL), and hemoglobin A1c (HbA1c), were analyzed and correlated with the gut microbiota. Bacterial community composition and diversity were detected in fecal samples using direct smear, sequencing, and real-time polymerase chain reaction (PCR). In this study, it was observed that indicators such as BMI, FPG, HbA1c, TC, and TG in T2DM patients were on the rise, concurrent with dysbiosis of the microbiota. We observed an increase in Enterococci and a decrease in Bacteroides, Bifidobacteria, and Lactobacilli in patients with T2DM. Meanwhile, total short-chain fatty acids (SCFAs) and D-lactate concentrations were decreased in the T2DM group. In addition, FPG was positively correlated with Enterococcus and negatively correlated with Bifidobacteria, Bacteroides, and Lactobacilli. This study reveals that microbiota dysbiosis is associated with disease severity in patients with T2DM. The limitation of this study is that only common bacteria were noted in this study, and more in-depth related studies are urgently needed.

Pathophysiology of type 2 diabetes in sub-Saharan Africans

Sub-Saharan Africa (SSA) is the region with the highest projected rates of increase in type 2 diabetes (129% by 2045), which will exacerbate the already high prevalence of type 2 diabetes complications and comorbidities in SSA. In addition, SSA is grappling with poverty-related health problems and infectious diseases and is also undergoing the most rapid rates of urbanisation globally. These socioenvironmental and lifestyle factors may interact with genetic factors to alter the pathophysiological sequence leading to type 2 diabetes in sub-Saharan African populations. Indeed, current evidence from SSA and the diaspora suggests that the pathophysiology of type 2 diabetes in Black Africans is different from that in their European counterparts. Studies from the diaspora suggest that insulin clearance is the primary defect underlying the development of type 2 diabetes. We propose that, among Black Africans from SSA, hyperinsulinaemia due to a combination of both increased insulin secretion and reduced hepatic insulin clearance is the primary defect, which promotes obesity and insulin resistance, exacerbating the hyperinsulinaemia and eventually leading to beta cell failure and type 2 diabetes. Nonetheless, the current understanding of the pathogenesis of type 2 diabetes and the clinical guidelines for preventing and managing the disease are largely based on studies including participants of predominately White European ancestry. In this review, we summarise the existing knowledge base and data from the only non-pharmacological intervention that explores the pathophysiology of type 2 diabetes in SSA. We also highlight factors that may influence the pathogenesis of type 2 diabetes in SSA, such as social determinants, infectious diseases and genetic and epigenetic influences.

Racial and Ethnic Disparities in Comorbidities in Youth With Type 2 Diabetes in the Pediatric Diabetes Consortium (PDC)

BACKGROUND

Type 2 diabetes in the U.S. is more prevalent in youth of minority racial-ethnic background, but disparities in health outcomes have not been examined in this population.

RESEARCH DESIGN AND METHODS

We examined racial-ethnic differences in the initial presentation and subsequent comorbidities in 1,217 youth with type 2 diabetes (63% girls) enrolled in the Pediatric Diabetes Consortium (PDC) Registry from February 2012 to June 2018. Demographic and clinical data were collected from medical records and participant self-report.

RESULTS

Overall, the mean age at presentation was 13.4 ± 2.4 years, and BMI was 35.0 ± 9.4 kg/m2. HbA1c was higher and C-peptide was lower in non-Hispanic Black (NHB) and Hispanic (H) youth compared with non-Hispanic White (NHW) youth. NHB were three times as likely to present in diabetic ketoacidosis (19%) versus NHW (6.3%) and H (7.5%), and NHB and H both had a worse HbA1c trajectory compared with NHW peers. Microalbuminuria was documented in 11%, hypertension in 34%, and dyslipidemia in 42% of Registry participants, with no significant difference among racial-ethnic groups. Nonalcoholic fatty liver disease (NAFLD) was diagnosed in 9% and 11% of H and NHW, respectively, versus 2% in NHB.

CONCLUSIONS

NHB and H youth with type 2 diabetes presented with worse metabolic control and had persistently worse HbA1c trajectories compared with NHW. Comorbidities exist in a large percentage of these youth independent of race-ethnicity, except for NAFLD being less prevalent in NHB. Greater efforts are needed to mitigate racial-ethnic disparities at diagnosis and in the management of youth with type 2 diabetes.

Accelerometer-Measured Physical Activity and Cardiometabolic Risk Factors by Race-Ethnicity: 2003-2006 NHANES

Previous studies suggest that the magnitude of morbidity/mortality reduction may differ between race-ethnic groups despite equated dose of physical activity (PA). The purpose of this study was to compare the potential racial-ethnic differences in cardiometabolic risk factors (CMRF) across quartiles of accelerometer-derived total activity counts/day (TAC/d) among US adults. The final sample (n=4144) included adults who participated in the 2003-2006 National Health and Nutrition Examination Survey (NHANES). CMRF included fasting glucose (FG), fasting insulin (FI), HOMA-IR, resting systolic (SBP) and diastolic blood pressure (DBP), waist circumference (WC), BMI, CRP, HDL-C, LDL-C, and triglycerides. Race-ethnic groups examined included non-Hispanic white (NHW), non-Hispanic black (NHB), and Mexican American (MA). In the highest quartile, NHW had significantly lower values of HOMA-IR, FI, SBP, BMI, WC, and HDL-C when compared to NHB. Compared to MA in the highest quartile, NHW had significantly lower values of HOMA-IR, FI, BMI, and triglycerides. Significant race-ethnic differences were found for several CMRF, especially among those who were in the top quartile of PA (e.g., the most active adults). It is probable that the protective effect of higher volumes of PA on CMRF is moderated by other non-PA factors distinct to NHB and MA.

Protective role of physical activity on type 2 diabetes: Analysis of effect modification by race-ethnicity

BACKGROUND

It is well known physical activity (PA) plays a role in the prevention of type 2 diabetes (T2D). However, the extent to which PA may affect T2D risk among different race-ethnic groups is unknown. Therefore, the aim of the present study was to systematically examine the effect modification of race-ethnicity on PA and T2D.

METHODS

The PubMed and Embase databases were systematically searched through June 2016. Study assessment for inclusion was conducted in three phases: title review (n = 13 022), abstract review (n = 2200), and full text review (n = 265). In all, 27 studies met the inclusion criteria and were used in the analysis. Relative risks (RRs) and 95% confidence intervals (CIs) were extracted and analyzed using Comprehensive Meta-Analysis software. All analyses used a random-effects model.

RESULTS

A significant protective summary RR, comparing the most active group with the least active PA group, was found for non-Hispanic White (RR 0.71, 95% CI 0.60-0.85), Asians (RR 0.76, 95% CI 0.67-0.85), Hispanics (RR 0.75, 95% CI 0.64-0.89), and American Indians (RR 0.73, 95% CI 0.60-0.88). The summary effect for non-Hispanic Blacks (RR 0.91, 95% CI 0.76-1.08) was not significant.

CONCLUSIONS

The results of the present study indicate that PA (comparing most to least active groups) provides significant protection from T2D, with the exception of non-Hispanic Blacks. The results also indicate a need for race-ethnicity-specific reporting of RRs in prospective cohort studies that incorporate multiethnic samples.

The efficacy and safety of canagliflozin across racial groups in patients with type 2 diabetes mellitus

OBJECTIVE

Canagliflozin, a sodium-glucose co-transporter 2 inhibitor, enhances urinary glucose excretion through an insulin-independent mode of action, and improves glycemic control in patients with type 2 diabetes mellitus (T2DM). This study assessed the efficacy and safety of canagliflozin across racial groups.

METHODS

The efficacy of canagliflozin 100 mg and 300 mg was evaluated by racial group using data pooled from four placebo-controlled phase 3 studies and two placebo-controlled sub-studies of a population of patients with inadequately controlled T2DM (N = 4158). Least-squares mean changes from baseline were calculated for hemoglobin A1c (HbA1c), systolic blood pressure (SBP), body weight (BW), cholesterol, and triglycerides. Safety/tolerability evaluation included reporting of general and prespecified adverse events (AEs).

RESULTS

A total of 75% of patients were White, 13% were Asian, 4% were Black/African American, and 8% were 'Other' (American Indian, Alaskan Native, mixed race, Native Hawaiian or other Pacific Islander, not reported, and unknown). Baseline demographics were similar for these groups. Dose-related reductions in HbA1c, BW, and SBP were observed with both canagliflozin doses in all racial groups. Canagliflozin was generally safe and well tolerated. Treatment with canagliflozin was associated with an increased rate of genital mycotic infections (GMIs) and urinary tract infections (UTIs) in all racial groups. GMIs were observed more often in Black/African American males and males from the 'Other' racial group, whereas UTIs and osmotic diuresis-related AEs were less common in Asians. Key study limitations include the high proportion of White patients compared with other racial groups and the fact that included studies were not powered to evaluate racial differences.

CONCLUSION

Canagliflozin was generally well tolerated and consistently associated with reductions in HbA1c, BW, and SBP in patients with T2DM independent of racial background. (ClinicalTrials.gov numbers: NCT01081834; NCT01106677; NCT01106625; NCT01106690; and NCT01032629.).