Racial/Ethnic Differences in Glycemic Control in Older Adults with Type 2 Diabetes: United States 2003-2014

Racial and ethnic differences in uncontrolled diabetes mellitus among adults taking antidiabetic medication

AIM

To examine whether racial and ethnic disparities in uncontrolled type 2 diabetes mellitus (T2DM) persist among those taking medication and after accounting for other demographic, socioeconomic, and health indicators.

METHODS

Adults aged ≥20 years with T2DM using prescription diabetes medication were among participants assessed in a retrospective cohort study of the National Health and Nutrition Examination Survey 2007-2018. We estimated weighted sequential multivariable logistic regression models to predict odds of uncontrolled T2DM (HbA1c ≥ 8%) from racial and ethnic identity, adjusting for demographic, socioeconomic, and health indicators.

RESULTS

Of 3649 individuals with T2DM who reported taking medication, 27.4% had uncontrolled T2DM (mean HgA1c 9.6%). Those with uncontrolled diabetes had a mean BMI of 33.8, age of 57.3, and most were non-Hispanic white (54%), followed by 17% non-Hispanic Black, and 20% Hispanic identity. In multivariable analyses, odds of uncontrolled T2DM among those with Black or Hispanic identities lessened, but persisted, after accounting for other indicators (Black OR 1.38, 97.5% CI: 1.04, 1.83; Hispanic OR 1.79, 97.5% CI 1.25, 2.57).

CONCLUSIONS

Racial and ethnic disparities in T2DM control persisted among individuals taking medication. Future research might focus on developmental and epigenetic pathways of disparate T2DM control across racially and ethnically minoritized populations.

Sodium-glucose cotransporter-2 inhibitors and incidence of atrial fibrillation in older adults with type 2 diabetes: a retrospective cohort analysis

Objectives

To investigate the risk of atrial fibrillation (AF) with sodium-glucose cotransporter-2 inhibitors (SGLT2is) compared to dipeptidyl peptidase-4 inhibitor (DPP4i) use in older US adults and across diverse subgroups.

Methods

We conducted a retrospective cohort analysis using claims data from 15% random samples of Medicare fee-for-service beneficiaries. Patients were adults with type 2 diabetes (T2D), no preexisting AF, and were newly initiated on SGLT2i or DPP4i. The outcome was the first incident AF. Inverse probability treatment weighting (IPTW) was used to balance the baseline covariates between the treatment groups including sociodemographics, comorbidities, and co-medications. Cox regression models were used to assess the effect of SGLT2i compared to DPP4i on incident AF.

Results

Of the 97,436 eligible individuals (mean age 71.2 ± 9.8 years, 54.6% women), 1.01% (n = 983) had incident AF over a median follow-up of 361 days. The adjusted incidence rate was 8.39 (95% CI: 6.67-9.99) and 11.70 (95% CI: 10.9-12.55) per 1,000 person-years in the SGLT2i and DPP4i groups, respectively. SGLT2is were associated with a significantly lower risk of incident AF (HR 0.73; 95% CI, 0.57 to 0.91; p = 0.01) than DPP4is. The risk reduction of incident AF was significant in non-Hispanic White individuals and subgroups with existing atherosclerotic cardiovascular diseases and chronic kidney disease.

Conclusion

Compared to the use of DPP4i, that of SGLT2i was associated with a lower risk of AF in patients with T2D. Our findings contribute to the real-world evidence regarding the effectiveness of SGLT2i in preventing AF and support a tailored therapeutic approach to optimize treatment selection based on individual characteristics.

Advancing Equity in Diabetes Prevention, Treatment, and Outcomes: Delivering on Our Values

Diabetes inequities exist from diabetes prevention to outcomes and are rooted in the social drivers (determinants) of health. Historical policies such as "redlining" have adversely affected diabetes prevalence, control, and outcomes for decades. Advancing diabetes equity requires multimodal approaches, addressing both individual-level diabetes education, self-management, and treatment along with addressing social needs, and working to improve upstream drivers of health. All individuals affected by diabetes must advocate for policies to advance diabetes equity at the organizational, local, state, and federal levels. Centering diabetes efforts and interventions on equity will improve diabetes treatment and care for all.

Glycemic outcomes of a family-focused intervention for adults with type 2 diabetes: Main, mediated, and subgroup effects from the FAMS 2.0 RCT

AIMS

Family/friend Activation to Motivate Self-care (FAMS) is a self-care support intervention delivered via mobile phones. We evaluated FAMS' effects on hemoglobin A1c (HbA1c) and intervention targets among adults with type 2 diabetes in a 15-month RCT.

METHODS

Persons with diabetes (PWDs) were randomized to FAMS or control with their support person (family/friend, optional). FAMS included monthly phone coaching and text messages for PWDs, and text messages for support persons over a 9-month intervention period.

RESULTS

PWDs (N = 329) were 52 % male, 39 % reported minoritized race or ethnicity, with mean HbA1c 8.6 ± 1.7 %. FAMS improved HbA1c among PWDs with a non-cohabitating support person (-0.64 %; 95 % CI [-1.22 %, -0.05 %]), but overall mean effects were not significant. FAMS improved intervention targets including self-efficacy, dietary behavior, and family/friend involvement during the intervention period; these improvements mediated post-intervention HbA1c improvements (total indirect effect -0.27 %; 95 % CI [-0.49 %, -0.09 %]) and sustained HbA1c improvements at 12 months (total indirect effect -0.19 %; 95 % CI [-0.40 %, -0.01 %]).

CONCLUSIONS

Despite improvements in most intervention targets, HbA1c improved only among PWDs engaging non-cohabitating support persons suggesting future family interventions should emphasize inclusion of these relationships. Future work should also seek to identify intervention targets that mediate improvements in HbA1c.

Metformin and SGLT2i as First-line Combination Therapy in Type 2 Diabetes: A Real-world Study With a Focus on Ethnicity

PURPOSE

Suboptimal glucose control early in the diagnosis of type 2 diabetes (T2D) is strongly associated with subsequent morbidity and mortality, termed the 'glycaemic legacy'. Additionally, it is known that Asian and Black individuals are at increased risk of T2D, and its associated complications compared to their White counterparts. However, ethnicity does not currently feature in the treatment algorithm of T2D, unlike in other cardiovascular disease states such as hypertension. We therefore sought to evaluate the real-world impact of early intensive treatment with combination therapy on cardiorenal outcomes compared to standard treatment in T2D, with a focus on ethnicity.

METHODS

We performed a retrospective cohort study of all patients aged 18 or over with T2D using the TriNetX platform. TriNetX is a global collaborative network providing access to real time, anonymised medical records. We included patients who were initiated with Metformin and an SGLT2i within one month of diagnosis of T2D and compared this cohort with individuals who received Metformin only for a period of at least 1 year. We evaluated cardiovascular and renal outcomes at three years and stratified by ethnicity. We excluded individuals with a personal history of an outcome of interest.

FINDINGS

We identified 49,651 individuals with T2D who were treated with Metformin and an SGLT2i and 1,028,806 patients with T2D who were treated with Metformin alone. A total of 98,094 individuals were included in the core analysis. The Metformin only group had a greater risk of mortality (RR 1.44, [95% CI 1.34-1.55], P<0.0001), CKD (RR 1.10, [95% CI 1.04-1.16], P = 0.0004), diabetic nephropathy (RR 1.06, [95% CI 1.01-1.12], P = 0.0239), heart failure (RR 1.13, [95% CI 1.07-1.21], P < 0.0001) and hospitalisation (RR 1.24, [95% CI 1.21-1.27], P < 0.0001) compared to individuals treated with Metformin and SGLT2i. Black individuals had a reduced risk of mortality (RR 0.71, [95% CI 0.55-0.92], P = 0.0099) and IHD (RR 0.73, [95% CI 0.64-0.84], P < 0.0001) compared to White individuals. Asian individuals had a reduced risk of heart failure (RR 0.61, [95% CI 0.41-0.91], P = 0.0134) and hospitalisation (RR 0.76, [95% CI 0.66-0.87], P = 0.0001) compared to White individuals.

IMPLICATIONS

Initial combination treatment within the first year of T2D diagnosis confers favourable cardio-metabolic outcomes when compared to standard therapy, even in patients without established cardiovascular disease. Black and Asian individuals in particular demonstrate a greater degree of benefit compared to White individuals. Further prospective studies with a focus on ethnicity are now required to validate these findings.

Use of herbal medicines for the management of type 2 diabetes: A systematic review of qualitative studies

BACKGROUND

Many people with Type 2 Diabetes Mellitus (T2DM) use herbal medicines, some of which can improve glycaemic control. Providing evidence-based advice on herbal medicines could be an effective intervention to improve control of diabetes, if it is designed to address key needs and concerns of T2DM patients.

AIM

To understand the views and experiences of patients and health professionals on herbal treatments for self-management of T2DM.

METHOD

MEDLINE, EMBASE, CINAHL, SOCIOFILE and Google Scholar were searched for qualitative studies in T2DM patients about their views on herbal medicines. Included papers were analysed using thematic synthesis.

RESULTS

Thirty-one papers (about 30 studies) were included: 20 from low-and-middle income countries, 10 from high income countries, and 1 internet-based study. Almost all studies from high income countries focussed on ethnic minorities. Many people with T2DM wanted a "cure", and often took advice from friends and family, but also traditional healers and mass media. However, they were reluctant to discuss herbal medicines with health professionals, whom they perceived as "closed-minded". They based their treatment decisions on personal experience (from "trial-and-error"), availability, cost and convenience of both herbal and conventional medicines. Most health professionals were reluctant to discuss herbal medicines, or recommended against their use, because of lack of knowledge and concerns about their quality, efficacy and potential interactions.

CONCLUSION

Evidence-based information could help to overcome the current lack of communication about herbal medicines between people with T2DM and health professionals.

Demographic Variables Associated With Diabetes Technology Awareness or Use in Adults With Type 2 Diabetes

Background

Studies in populations with type 1 diabetes highlight racial/ethnic disparities in the use of diabetes technology; however, little is known about disparities among those with type 2 diabetes. This project investigates the racial/ethnic and socioeconomic disparities in diabetes technology awareness and use in adults with type 2 diabetes in the ambulatory setting.

Methods

Adults ≥40 years of age with type 2 diabetes in ambulatory care were invited to participate via an e-mail link to a de-identified REDCap (Research Electronic Data Capture) questionnaire. Variables, including awareness and use of continuous glucose monitoring (CGM) and insulin pumps, were summarized descriptively using frequencies and percentages and were compared across racial/ethnic groups, education level, and income using Pearson χ2 or Fisher exact tests.

Results

The study included 116 participants, most of whom (62%) were White, elderly Medicare recipients. Compared with White participants, those of racially/ethnically minoritized groups were less likely to be aware of CGM (P = 0.013) or insulin pumps (P = 0.001). Participants with a high school education or less were also less likely to be aware of insulin pumps (P = 0.041). Interestingly, neither awareness nor use of CGM or insulin pumps was found to be associated with income.

Conclusion

This cross-sectional analysis suggests that racially/ethnically minoritized groups and individuals with lower education have less awareness of CGM or insulin pumps.

Glycemic outcomes of a family-focused intervention for adults with type 2 diabetes: Main, mediated, and subgroup effects from the FAMS 2.0 RCT

Aims

Family/friends Activation to Motivate Self-care (FAMS) is a self-care support intervention delivered via mobile phones. We evaluated FAMS effects on hemoglobin A1c (HbA1c) and intervention targets among adults with type 2 diabetes in a 15-month RCT.

Methods

Persons with diabetes (PWDs) and their support persons (family/friend, optional) were randomized to FAMS or control. FAMS included monthly phone coaching and text messages for PWDs, and text messages for support persons over a 9-month intervention period.

Results

PWDs (N=329) were 52% male, 39% from minoritized racial or ethnic groups, with mean HbA1c 8.6±1.7%. FAMS improved HbA1c among PWDs with a non-cohabitating support person (-0.64%; 95% CI [-1.22%, -0.05%]), but overall effects were not significant. FAMS improved intervention targets including self-efficacy, dietary behavior, and family/friend involvement during the intervention period; these improvements mediated post-intervention HbA1c improvements (total indirect effect -0.27%; 95% CI [-0.49%, -0.09%]) and sustained HbA1c improvements at 12 months (total indirect effect -0.19%; 95% CI [-0.40%, -0.01%]).

Conclusions

Despite improvements in most intervention targets, HbA1c improved only among PWDs engaging non-cohabitating support persons suggesting future family interventions should emphasize inclusion of these relationships. Future work should also seek to identify intervention targets that mediate improvements in HbA1c.

Mobile Health Intervention in Patients With Type 2 Diabetes: A Randomized Clinical Trial

Importance

Clinical pharmacists and health coaches using mobile health (mHealth) tools, such as telehealth and text messaging, may improve blood glucose levels in African American and Latinx populations with type 2 diabetes.

Objective

To determine whether clinical pharmacists and health coaches using mHealth tools can improve hemoglobin A1c (HbA1c) levels.

Design, Setting, and Participants

This randomized clinical trial included 221 African American or Latinx patients with type 2 diabetes and elevated HbA1c (≥8%) from an academic medical center in Chicago. Adult patients aged 21 to 75 years were enrolled and randomized from March 23, 2017, through January 8, 2020. Patients randomized to the intervention group received mHealth diabetes support for 1 year followed by monitored usual diabetes care during a second year (follow-up duration, 24 months). Those randomized to the waiting list control group received usual diabetes care for 1 year followed by the mHealth diabetes intervention during a second year.

Interventions

The mHealth diabetes intervention included remote support (eg, review of glucose levels and medication intensification) from clinical pharmacists via a video telehealth platform. Health coach activities (eg, addressing barriers to medication use and assisting pharmacists in medication reconciliation and telehealth) occurred in person at participant homes and via phone calls and text messaging. Usual diabetes care comprised routine health care from patients' primary care physicians, including medication reconciliation and adjustment.

Main Outcomes and Measures

Outcomes included HbA1c (primary outcome), blood pressure, cholesterol, body mass index, health-related quality of life, diabetes distress, diabetes self-efficacy, depressive symptoms, social support, medication-taking behavior, and diabetes self-care measured every 6 months.

Results

Among the 221 participants (mean [SD] age, 55.2 [9.5] years; 154 women [69.7%], 148 African American adults [67.0%], and 73 Latinx adults [33.0%]), the baseline mean (SD) HbA1c level was 9.23% (1.53%). Over the initial 12 months, HbA1c improved by a mean of -0.79 percentage points in the intervention group compared with -0.24 percentage points in the waiting list control group (treatment effect, -0.62; 95% CI, -1.04 to -0.19; P = .005). Over the subsequent 12 months, a significant change in HbA1c was observed in the waiting list control group after they received the same intervention (mean change, -0.57 percentage points; P = .002), while the intervention group maintained benefit (mean change, 0.17 percentage points; P = .35). No between-group differences were found in adjusted models for secondary outcomes.

Conclusions and Relevance

In this randomized clinical trial, HbA1c levels improved among African American and Latinx adults with type 2 diabetes. These findings suggest that a clinical pharmacist and health coach-delivered mobile health intervention can improve blood glucose levels in African American and Latinx populations and may help reduce racial and ethnic disparities.

Trial Registration

ClinicalTrials.gov Identifier: NCT02990299.

Therapeutic Inertia and Delays in Insulin Intensification in Type 2 Diabetes: A Literature Review

Background

Therapeutic inertia leading to delays in insulin initiation or intensification is a major contributor to lack of optimal diabetes care. This report reviews the literature summarizing data on therapeutic inertia and delays in insulin intensification in the management of type 2 diabetes.

Methods

A literature search was conducted of the Allied & Complementary Medicine, BIOSIS Previews, Embase, EMCare, International Pharmaceutical Abstracts, MEDLINE, and ToxFile databases for clinical studies, observational research, and meta-analyses from 2012 to 2022 using search terms for type 2 diabetes and delay in initiating/intensifying insulin. Twenty-two studies met inclusion criteria.

Results

Time until insulin initiation among patients on two to three antihyperglycemic agents was at least 5 years, and mean A1C ranged from 8.7 to 9.8%. Early insulin intensification was linked with reduced A1C by 1.4%, reduction of severe hypoglycemic events from 4 to <1 per 100 person-years, and diminution in risk of heart failure (HF) by 18%, myocardial infarction (MI) by 23%, and stroke by 28%. In contrast, delayed insulin intensification was associated with increased risk of HF (64%), MI (67%), and stroke (51%) and a higher incidence of diabetic retinopathy. In the views of both patients and providers, hypoglycemia was identified as a primary driver of therapeutic inertia; 75.5% of physicians reported that they would treat more aggressively if not for concerns about hypoglycemia.

Conclusion

Long delays before insulin initiation and intensification in clinically eligible patients are largely driven by concerns over hypoglycemia. New diabetes technology that provides continuous glucose monitoring may reduce occurrences of hypoglycemia and help overcome therapeutic inertia associated with insulin initiation and intensification.

The use of telemedicine in peripheral artery disease and limb salvage

Chronic limb-threatening ischemia represents the morbid end stage of severe peripheral artery disease, with significant impact on patient quality of life. Early diagnosis of arterial insufficiency and referral for vascular intervention are essential for successful limb salvage. Disparate outcomes have been reported among patients residing in rural areas due to decreased access to care. Remote telemedicine outreach programs represent an opportunity to improve access to care in these rural communities. Establishment of a telehealth program requires identification of communities most in need of specialty care. After locating an ideal site, collaboration with local providers is necessary to develop a program that meets the specific needs of providers and patients. Surgeon guidance in development of screening and management algorithms ensures that patients obtain care reliably and with adjustments as needed to suit the referring provider, the patient, and the specialist. Telehealth evaluations can limit the financial burden associated with travel, while ensuring access to higher levels of care than are available in the patients' immediate area. Multiple barriers to telehealth exist. These include limited reimbursement, local provider resistance to new referral patterns, lack of in-person interaction and evaluation, and the inability to do a physical examination. Improved reimbursement models have made telehealth feasible, although care must be taken to ensure that practice patterns complement existing resources and are designed in a way that omits the need for in-person evaluation until the time of specialist intervention. Telemedicine is an underused tool in the arsenal of vascular surgeons. Targeted telehealth programs aid in increasing patient access to expert-level care, thereby improving health disparities that exist in rural populations.

Changes in racial and ethnic disparities in glucose-lowering drug utilization and glycated haemoglobin A1c in US adults with diabetes: 2005-2018

AIM

To examine changes in racial and ethnic disparities in glucose-lowering drugs (GLD) use and glycated haemoglobin A1c in US adults with diabetes from 2005 to 2018.

METHODS

We conducted pooled cross-sectional analysis using data from the 2005-2018 Medical Expenditure Panel Surveys, and the 2005-2018 National Health and Nutrition Examination Survey. Individuals ≥18 years with diabetes were included. Racial and ethnic disparities were measured in (a) newer non-insulin GLD use; (b) insulin analogue use; (c) non-insulin GLDs adherence; (d) insulin adherence; and (e) glucose management, along with (f) the proportion of the disparities explained by potential contributing factors.

RESULTS

From 2005 to 2018, racial and ethnic disparities persisted in newer GLD use, non-insulin GLDs adherence, insulin analogue use and glucose management. In 2018, compared with non-Hispanic white adults, non-Hispanic black, Hispanic and other race/ethnicity groups had lower rates of using newer GLDs (adjusted risk ratio: 0.44, 0.52, 0.64, respectively; p < .05 for all) and insulin analogues (adjusted risk ratio: 0.93, 0.89, 0.95, respectively; p < .05 for all except other groups), lower non-insulin GLD adherence (proportion of days covered: -4.5%, -5.6%, -4.3%, respectively; p < .05 for all), higher glycated haemoglobin A1c (0.29%, 0.32%, 0.02%, respectively; p < .05 for all except other group), and similar insulin adherences. Socioeconomic and health status were the main contributors to these disparities.

CONCLUSIONS

Our findings provide evidence of racial and ethnic disparities in newer GLD use and quality of care in glucose management. Our study results can inform decision-makers of the status of racial and ethnic disparities and identify ways to reduce these disparities.

HbA1c and physical performance in older adults from different aging epidemiological contexts: Longitudinal findings of the International Mobility in Aging Study (IMIAS)

OBJECTIVE

This study aimed to assess the longitudinal predictions between glycated hemoglobin A1c (HbA1c) and physical performance scores in different epidemiological contexts of aging.

MATERIAL AND METHODS

Longitudinal data of 1,337 older people from three countries (Canada, Brazil and Colombia) of the International Mobility in Aging Study (IMIAS) were used to assess the relationship between HbA1c and Short Physical Performance Battery (SPPB) scores between 2012 and 2016. Linear Mixed Models grouped by sex and adjusted by Age, Study site, Chronic Conditions, Anthropometric Measures, and Inflammatory Level were used to estimate the influence of HbA1c and covariates on SPPB scores.

RESULTS

At the IMIAS baseline, Latin American (LA) cities had higher HbA1c averages compared to Canadian cities, with Natal (Brazil) being the city with the highest HbA1c averages in men and women (6.32 ± 1.49; 6,56 ± 1.70 respectively). SPPB scores were significantly lower in LA cities, and older people in Natal had lower SPPB averages in men (9.67 ± 2.38; p-value < 0.05) and women (8.52 ± 2.33; p-value <0.05). In the multivariate mixed linear models of longitudinal analyses, HbA1c was significantly associated with lower SPPB scores in men (β = -0.25, 95% CI: -0.39 to -0.12, p-value = 0.02) but not in women.

CONCLUSION

High HbA1c levels at baseline were longitudinally associated in older adults from different countries, and this association was observed only in men and not in women. This study highlights a possible influence of gender on this relationship.

Association between medication regimen complexity and glycemic control among patients with type 2 diabetes

INTRODUCTION

Type 2 diabetes mellitus (T2DM) and comorbid conditions require patients to take complex medication regimens. Greater regimen complexity has been associated with poorer T2DM management; however, the relationship between overall regimen complexity and glycemic control is unclear.

OBJECTIVES

Our objectives were: (1) to examine associations between regimen complexity (with the Medication Regimen Complexity Index [MRCI]) and glycemic control (A1C), and (2) to compare overall MRCI with other measures of regimen complexity (overall and diabetes-specific medication count) and diabetes-specific MRCI.

METHODS

This was a secondary data analysis of cross-sectional data from a parent trial. Participants were patients with T2DM taking at least 3 chronic medications followed in safety net clinics in the Chicago area. The MRCI measures complexity based on dosing frequency, route of administration, and special instructions for prescribed medications. MRCI scores were created for overall regimens and diabetes-specific medications. Sociodemographics and outpatient visit utilization were included in models as covariates. Linear regression was used to examine the associations between variables of interest and hemoglobin A1C.

RESULTS

Participants (N = 432) had a mean age of 56.9 years, most were female (66.0%), and Hispanic or Latino (73.3%). Regimen complexity was high based on overall medications (mean = 6.6 medications, SD: 3.09) and MRCI (mean = 21.4, SD: 11.3). Higher diabetes-specific MRCI was associated with higher A1C in bivariate and multivariable models. In multivariable models, overall MRCI greater than 14, fewer outpatient health care visits, male gender, and absence of health insurance were independently associated with higher A1C. The variance in A1C explained by MRCI was higher compared to medication count for overall and diabetes-specific regimen complexity.

CONCLUSIONS

More complex regimens are associated with worse A1C and measuring complexity with MRCI may have advantages. Deprescribing, increasing insurance coverage, and promoting engagement in health care may improve A1C among underserved populations with complex regimens.

Racial and ethnic disparities in 3-year outcomes following infrainguinal bypass for chronic limb-threatening ischemia

OBJECTIVE

Black and Hispanic patients have had higher rates of chronic limb-threatening ischemia (CLTI) and experienced worse perioperative outcomes after lower extremity bypass compared with White patients. The underlying reasons for these disparities have remained unclear, and data on 3-year outcomes are limited. Therefore, we examined the differences in 3-year outcomes after open infrainguinal bypass for CLTI stratified by race/ethnicity and explored the potential factors contributing to these differences.

METHODS

We identified all CLTI patients who had undergone primary open infrainguinal bypass in the Vascular Quality Initiative registry from 2003 to 2017 with linkage to Medicare claims through 2018 for the 3-year outcomes. Our primary outcomes were the 3-year rates of major amputation, reintervention, and mortality. We also recorded the 30-day major adverse limb events (MALE) defined as major amputation or reintervention. We used Kaplan-Meier estimation methods and multivariable Cox regression analyses to evaluate the outcomes stratified by race/ethnicity and identify contributing factors.

RESULTS

Of the 7108 patients with CLTI, 5599 (79%) were non-Hispanic White, 1053 (15%) were Black, 48 (1%) were Asian, and 408 (6%) were Hispanic patients. Compared with White patients, Black patients had higher rates of 3-year major amputation (Black vs White, 32% vs 19%; hazard ratio [HR], 1.9; 95% confidence interval [CI], 1.7-2.2), reintervention (Black vs White, 61% vs 57%; HR, 1.2; 95% CI, 1.1-1.3), and 30-day MALE (Black vs White, 8.1% vs 4.9%; HR, 1.3; 95% CI, 1.2-1.4) but lower mortality (Black vs White, 38% vs 42%; HR, 0.9; 95% CI, 0.8-0.99). Hispanic patients also experienced higher rates of amputation (Hispanic vs White, 27% vs 19%; HR, 1.6; 95% CI, 1.3-2.0), reintervention (Hispanic vs White, 70% vs 57%; HR, 1.4; 95% CI, 1.2-1.6), and MALE (Hispanic vs White, 8.7% vs 4.9%; HR, 1.5; 95% CI, 1.3-1.7. However, mortality was similar between the two groups (Hispanic vs White, 38% vs 42%; HR, 0.88; 95% CI, 0.76-1.0). The low number of Asian patients prevented a meaningful assessment of amputation (Asian vs White, 20% vs 19%; HR, 0.93; 95% CI, 0.44-2.0), reintervention (Asian vs White, 55% vs 57%; HR, 0.79; 95% CI, 0.51-1.2), MALE (Asian vs White, 8.5% vs 4.9%; HR, 0.71; 95% CI, 0.46-1.1), or mortality (Asian vs White, 36% vs 42%; HR, 0.83; 95% CI, 0.52-1.3). In the adjusted analyses, the association of Black race and Hispanic ethnicity with amputation and reintervention was explained by differences in the demographic characteristics (ie, age, sex) and baseline comorbidities (ie, tobacco use, diabetes, renal disease).

CONCLUSIONS

Compared with White patients, Black and Hispanic patients had higher 3-year major amputation and reintervention rates. However, mortality was lower for Black patients than for the White patients and similar between Hispanic and White patients. Disparities in amputation and reintervention were partly attributable to differences in demographic characteristics and the higher prevalence of comorbidities in Black and Hispanic patients with CLTI. Future work is necessary to determine whether interventions to improve access to care and reduce the burden of comorbidities in these populations will confer limb salvage benefits.

Effect of cognitive impairment on risk of death in Hispanic/Latino adults over the age of 50 residing in the United States with and without diabetes: Data from the Health and Retirement Study 1995-2014

OBJECTIVE

To understand the relationship between mortality and cognitive function among older US Hispanic adults with and without diabetes.

METHODS

Data from the Health and Retirement Study (1995-2014) were analyzed. Cox proportional hazard models were used to estimate the association between mortality and cognitive function. Models were stratified by diabetes.

RESULTS

Four thousand thirteen older US Hispanic adults were included. Fully adjusted models for individuals with diabetes showed those with mild cognitive impairment (MCI; hazard ratio [HR]: 1.61; 95% confidence interval [CI]: 1.06, 2.45; P = .025) and dementia (HR: 2.14; 95% CI: 1.25, 3.67; P = .006) had increased mortality compared to normal cognition. Fully adjusted models for individuals without diabetes showed those with MCI (HR: 1.87; 95% CI: 1.28, 2.74; P = .001) and dementia (HR: 3.25; 95% CI: 1.91, 5.55; P < .001) had increased mortality compared to normal cognition.

CONCLUSIONS

Cognitive impairment is associated with increased mortality in older US Hispanic adults with and without diabetes. Clinicians should regularly assess cognitive function in this group to quickly identify declines and make appropriate referrals for support to optimize health and reduce mortality.

Differences in Hemoglobin A1c during Pregnancy between Non-Hispanic Black versus White Women with Prepregnancy Diabetes

OBJECTIVE

The objective of this was to determine whether the change in hemoglobin A1c (HbA1c) from early to late pregnancy differs between non-Hispanic Black and White women with prepregnancy diabetes.

STUDY DESIGN

A retrospective analysis was performed from an integrated prenatal and diabetes care program from 2012 to 2016. We compared HbA1c as a continuous measure and secondarily, HbA1c <6.5%, cross-sectionally, and longitudinally in early (approximately 10 weeks) and late (approximately 31 weeks) pregnancies. Linear and logistic regression were used and adjusted for age, body mass index, White diabetes class, medication use, diabetes type, gestational age at baseline HbA1c measurement, and baseline hemoglobin.

RESULTS

Among 296 non-Hispanic Black (35%) and White pregnant women (65%) with prepregnancy diabetes (39% type 1 and 61% type 2), Black women were more likely to experience increased community-level social determinants of health as measured by the Social Vulnerability Index (SVI) and were less likely to have type 1 diabetes and have more severe diabetes versus White women (p < 0.05). Black women had higher mean HbA1c (7.8 vs. 7.4%; beta: 0.75; 95% confidence interval [CI]: 0.30-1.19) and were less likely to have HbA1c < 6.5% at 10 weeks compared with White women (24 vs. 35%; adjusted odds ratio: 0.45; 95% CI: 0.24-0.81) but not after adjusting for SVI. At 31 weeks, both groups had similar mean HbA1c (both 6.5%) and were equally as likely to have HbA1c < 6.5% (57 vs. 54%). From early to late pregnancy, Black women had a higher percentage decrease in HbA1c (1.3 vs. 0.9%; beta = 0.63; 95% CI: 0.27-0.99) and were equally as likely to have an improvement or stable HbA1C < 6.5% from 10 to 31 weeks, with both groups having a similar mean HbA1c (6.5%) at 31 weeks.

CONCLUSION

Despite experiencing greater community-level social determinants of health, Black women with pregestational diabetes had a larger reduction in HbA1c and were able to equally achieve the target of HbA1c < 6.5% by late pregnancy compared with White women as part of an integrated diabetes and prenatal care program.

KEY POINTS

· An integrated diabetes and pregnancy care program may decrease racial and ethnic disparities in glycemic control.. · Black women had a larger reduction in HbA1c versus White women.. · Black women were able to equally achieve the target of HbA1c < 6.5% by late pregnancy versus White women..

Adapting Physiology in Functional Human Islet Organogenesis

Generation of three-dimensional (3D)-structured functional human islets is expected to be an alternative cell source for cadaveric human islet transplantation for the treatment of insulin-dependent diabetes. Human pluripotent stem cells (hPSCs), such as human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs), offer infinite resources for newly synthesized human islets. Recent advancements in hPSCs technology have enabled direct differentiation to human islet-like clusters, which can sense glucose and secrete insulin, and those islet clusters can ameliorate diabetes when transplanted into rodents or non-human primates (NHPs). However, the generated hPSC-derived human islet-like clusters are functionally immature compared with primary human islets. There remains a challenge to establish a technology to create fully functional human islets in vitro, which are functionally and transcriptionally indistinguishable from cadaveric human islets. Understanding the complex differentiation and maturation pathway is necessary to generate fully functional human islets for a tremendous supply of high-quality human islets with less batch-to-batch difference for millions of patients. In this review, I summarized the current progress in the generation of 3D-structured human islets from pluripotent stem cells and discussed the importance of adapting physiology for in vitro functional human islet organogenesis and possible improvements with environmental cues.

Disparities in HbA1c testing between aging US Latino and non-Latino white primary care patients

US Latinos disproportionately face diabetes-related disparities compared to non-Latino Whites. A number of barriers, including linguistic and cultural discordance, have been consistently linked to these disparities. Glycated hemoglobin (HbA1c) testing is used to assess glycemic control among individuals living with diabetes. This study aimed to compare HbA1c levels and corresponding testing rates among non-Latino Whites and Latinos with both English and Spanish preference from a national cohort of primary care patients within community health centers. We analyzed electronic health records from patients who turned 50 years of age (n = 66,921) and were diagnosed with diabetes during or prior to the study period. They also must have been under observation for at least one year from January 1, 2013 to December 31, 2017. We calculated the rates of HbA1c tests each person received over the number of years observed and used covariate-adjusted negative binomial regression to estimate incidence rate ratios for Spanish preferring Latinos and English preferring Latinos compared to non-Latino Whites. Spanish preferring Latinos (rate ratio = 1.23, 95% CI = 1.16-1.30), regardless of HbA1c level, had higher testing rates than non-Latino Whites and English preferring Latinos. English preferring Latinos with controlled HbA1c levels had higher rates of HbA1c testing compared to non-Latino whites. Overall, the Latinos with Spanish preference maintained higher HbA1c testing rates and had disproportionately higher rates of uncontrolled HbA1c levels compared to non-Latino whites. Future efforts should focus on understanding effective approaches to increasing engagement among Spanish preferring Latinos and addressing organizational-level barriers, given HbA1c disparities.

Capitated versus fee-for-service reimbursement and quality of care for chronic disease: a US cross-sectional analysis

BACKGROUND

Upcoming alternative payment models Primary Care First (PCF) and Kidney Care Choices (KCC) incorporate capitated payments for chronic disease management. Prior research on the effect of capitated payments on chronic disease management has shown mixed results. We assessed the patient, physician, and practice characteristics of practices with capitation as the majority of revenue, and evaluated the association of capitated reimbursement with quality of chronic disease care.

METHODS

We performed a cross-sectional analysis of visits in the United States' National Ambulatory Medical Care Survey (NAMCS) for patients with hypertension, diabetes, or chronic kidney disease (CKD). Our predictor was practice reimbursement type, classified as 1) majority capitation, 2) majority FFS, or 3) other reimbursement mix. Outcomes were quality indicators of hypertension control, diabetes control, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker (ACEi/ARB) use, and statin use.

RESULTS

About 9% of visits were to practices with majority capitation revenue. Capitated practices, compared with FFS and other practices, had lower visit frequency (3.7 vs. 5.2 vs. 5.2, p = 0.006), were more likely to be located in the West Census Region (55% vs. 18% vs. 17%, p < 0.001), less likely to be solo practice (21% vs. 37% vs. 35%, p = 0.005), more likely to be owned by an insurance company, health plan or HMO (24% vs. 13% vs. 13%, p = 0.033), and more likely to have private insurance (43% vs. 25% vs. 19%, p = 0.004) and managed care payments (69% vs. 23% vs. 26%, p < 0.001) as the majority of revenue. The prevalence of controlled hypertension, controlled diabetes, ACEi/ARB use, and statin use was suboptimal across practice reimbursement types. Capitated reimbursement was not associated with differences in hypertension, diabetes, or CKD quality indicators, in multivariable models adjusting for patient, physician, and practice characteristics.

CONCLUSIONS

Practices with majority capitation revenue differed substantially from FFS and other practices in patient, physician, and practice characteristics, but were not associated with consistent quality differences. Our findings establish baseline estimates of chronic disease quality of care performance by practice reimbursement composition, informing chronic disease care delivery within upcoming payment models.

When Less Is More: Identifying Patients With Type 2 Diabetes Engaging in Unnecessary Blood Glucose Monitoring

This study examined whether certain patient characteristics are associated with the prescribing of self-monitoring of blood glucose for patients with type 2 diabetes who are not using insulin and have well-controlled blood glucose. Against recommendations, one-third of the patient sample from a large health network in North Carolina (N = 9,338) received a prescription for testing supplies (i.e., strips or lancets) within the prior 18 months. Women, African Americans, individuals prescribed an oral medication, nonsmokers, and those who were underweight or normal weight all had greater odds of receiving such a prescription. These results indicate that providers may have prescribing tendencies that are potentially biased against more vulnerable patient groups and contrary to guidelines.

Ethnic Disparities in Diabetes

Diabetes disproportionably affects minorities in the United States. Substantial disparities exist in diabetes incidence, glycemic control, complications, mortality, and management. The most important biologic contributors to diabetes disparities are obesity, insulin resistance, and inadequate glycemic control. Providers and health systems must also recognize the behavioral, social, and environmental factors that promote and sustain racial/ethnic differences in diabetes and its complications. Metformin and sodium-glucose cotransporter 2 inhibitors are the most convenient drugs for treatment of diabetes in minority patients. Multilevel interventions at the patient, provider, health system, community, and policy levels are needed to reduce diabetes disparities in high-risk groups.

The effect of comorbidities on glycemic control among Colombian adults with diabetes mellitus: a longitudinal approach with real-world data

BACKGROUND

Achieving an optimal glycemic control has been described to reduce the incidence of diabetes mellitus (DM) related complications. The association between comorbidities and glycemic control remains unclear. Our aim is to evaluate the effect of comorbidities on glycemic control in people living with DM.

METHODS

A retrospective longitudinal study on data from the National Registry of Chronic Kidney Disease from 2014 to 2019 in Colombia. The outcome was poor glycemic control (PGC = HbA1c ≥7.0%). The association between each comorbidity (hypertension (HTN), chronic kidney disease (CKD) or obesity) and PGC was evaluated through multivariate mixed effects logistic regression models. The measures of effect were odds ratios (OR) and their 95% confidence intervals (CI). We also evaluated the main associations stratified by gender, insurance, and early onset diabetes as well as statistical interaction between each comorbidity and ethnicity.

RESULTS

From 969,531 people at baseline, 85% had at least one comorbidity; they were older and mostly female. In people living with DM and CKD, the odds of having a PGC were 78% (OR: 1.78, CI 95%: 1.55-2.05) higher than those without CKD. Same pattern was observed in obese for whom the odds were 52% (OR: 1.52, CI 95%: 1.31-1.75) higher than in non-obese. Non-significant association was found between HTN and PGC. We found statistical interaction between comorbidities and ethnicity (afro descendant) as well as effect modification by health insurance and early onset DM.

CONCLUSIONS

Prevalence of comorbidities was high in adults living with DM. Patients with concomitant CKD or obesity had significantly higher odds of having a PGC.

Who Will Be Responsible for the Dialysis Bill? A Case Report and Narrative Review of Insulin Affordability 100 Years After the Discovery of Insulin

A 46-year-old woman was type 1 diabetes diagnosed at the age of 9 who had previously been on an insulin pump. Other co-morbidities included CKD IV, HTN, and hypothyroidism. She presented with hyperglycemia of 400 mg/dl and fluid retention. Her GFR had decreased to 13. Her physical exam was notable for respiratory distress and anasarca. She failed to respond to aggressive IV diuresis and urgent hemodialysis was initiated. The patient had been lost to outpatient follow-up for a year. She had been co-managed by an endocrinologist and a primary care physician but had stopped going to her endocrinologist over a year ago due to inability to afford the co-pays. She subsequently lost her insurance and had to pay out of pocket for her insulin; at this point, she decided to stop seeing her PCP and began to ration her insulin. Due to social stigma, she did not mention her financial issues to her healthcare providers. After identifying these challenges, we decided to start her on a more affordable regimen of NPH insulin. Through social work assistance, we were able to obtain a charity hemodialysis chair and discharge her home. She applied to Medicaid. Healthcare expenditure with regard to diabetes rose to $327 billion from $245 billion in 2012. The price of insulin has continued to increase even after the drug's patent has expired due to the combination of FDA requirements, a monopoly in the insulin market, and the lack of federal price controls and Pharmacy Benefits Managers. The high out of pocket costs for insulin has led to many instances of insulin rationing among both uninsured and insured. This led to death in some cases as well as poorly controlled diabetes with increased complications and mortality as in our case. We present a case report and narrative review on insulin affordability.

Remote patient monitoring sustains reductions of hemoglobin A1c in underserved patients to 12 months

AIMS

We sought to determine whether underserved patients enrolled in a statewide remote patient monitoring (RPM) program for diabetes achieve sustained improvements in hemoglobin A_1c at 6 and 12 months and whether those improvements are affected by demographic and clinical variables.

METHODS

Demographic and clinical variables were obtained at baseline, 6 months and 12 months. Baseline HbA1c values were compared with those obtained at 6 and 12 months via paired t-tests. A multivariable regression model was developed to identify patient-level variables associated with HbA_1c change at 12 months.

RESULTS

HbA_1c values were obtained for 302 participants at 6 months and 125 participants at 12 months. Compared to baseline, HbA_1c values were 1.8% (19 mmol/mol) lower at 6 months (p < 0.01) and 1.3% (14 mmol/mol) lower at 12 months (p < 0.01). Reductions at 12 months were consistent across clinical settings. A regression model for change in HbA_1c showed no statistically significant difference for patient age, sex, race, household income, insurance, or clinic type.

CONCLUSIONS

Patients enrolled in RPM had improved diabetes control at 6 and 12 months. Neither clinic type nor sociodemographic variables significantly altered the likelihood that patients would benefit from this type of technology. These results suggest the promise of RPM for delivering care to underserved populations.

Sex and Race Differences in the Risk of Ischemic Stroke Associated With Fasting Blood Glucose in REGARDS

OBJECTIVE

To investigate sex and race differences in the association between fasting blood glucose (FBG) and risk of ischemic stroke (IS).

METHODS

This prospective longitudinal cohort study included adults age ≥45 years at baseline in the Reasons for Geographic And Racial Differences in Stroke Study, followed for a median of 11.4 years. The exposure was baseline FBG (mg/dL); suspected IS events were ascertained by phone every 6 months and were physician-adjudicated. Cox proportional hazards were used to assess the adjusted sex/race-specific associations between FBG (by category and as a restricted cubic spline) and incident IS.

RESULTS

Of 20,338 participants, mean age was 64.5 (SD 9.3) years, 38.7% were Black, 55.4% were women, 16.2% were using diabetes medications, and 954 IS events occurred. Compared to FBG <100, FBG ≥150 was associated with 59% higher hazards of IS (95% confidence interval [CI] 1.21-2.08) and 61% higher hazards of IS among those on diabetes medications (95% CI 1.12-2.31). The association between FBG and IS varied by race/sex (hazard ratio, FBG ≥150 vs FBG <100: White women 2.05 [95% CI 1.23-3.42], Black women 1.71 [95% CI 1.10-2.66], Black men 1.24 [95% CI 0.75-2.06], White men 1.46 [95% CI 0.93-2.28], p _{FBG×race/sex} = 0.004). Analyses using FBG splines suggest that sex was the major contributor to differences by race/sex subgroups.

CONCLUSIONS

Sex differences in the strength and shape of the association between FBG and IS are likely driving the significant differences in the association between FBG and IS across race/sex subgroups. These findings should be explored further and may inform tailored stroke prevention guidelines.

A Pharmacist and Health Coach-Delivered Mobile Health Intervention for Type 2 Diabetes: Protocol for a Randomized Controlled Crossover Study

Background

Aggressive management of blood glucose, blood pressure, and cholesterol through medication and lifestyle adherence is necessary to minimize the adverse health outcomes of type 2 diabetes. However, numerous psychosocial and environmental barriers to adherence prevent low-income, urban, and ethnic minority populations from achieving their management goals, resulting in diabetes complications. Health coaches working with clinical pharmacists represent a promising strategy for addressing common diabetes management barriers. Mobile health (mHealth) tools may further enhance their ability to support vulnerable minority populations in diabetes management.

Objective

The aim of this study is to evaluate the impact of an mHealth clinical pharmacist and health coach–delivered intervention on hemoglobin A_1c (HbA_1c, primary outcome), blood pressure, and low-density lipoprotein (secondary outcomes) in African-Americans and Latinos with poorly controlled type 2 diabetes.

Methods

A 2-year, randomized controlled crossover study will evaluate the effectiveness of an mHealth diabetes intervention delivered by a health coach and clinical pharmacist team compared with usual care. All patients will receive 1 year of team intervention, including lifestyle and medication support delivered in the home with videoconferencing and text messages. All patients will also receive 1 year of usual care without team intervention and no home visits. The order of the conditions received will be randomized. Our recruitment goal is 220 urban African-American or Latino adults with uncontrolled type 2 diabetes (HbA_1c ≥8%) receiving care from a largely minority-serving, urban academic medical center. The intervention includes the following: health coaches supporting patients through home visits, phone calls, and text messaging and clinical pharmacists supporting patients through videoconferences facilitated by health coaches. Data collection includes physiologic (HbA_1c, blood pressure, weight, and lipid profile) and survey measures (medication adherence, diabetes-related behaviors, and quality of life). Data collection during the second year of study will determine the maintenance of any physiological improvement among participants receiving the intervention during the first year.

Results

Participant enrollment began in March 2017. We have recruited 221 patients. Intervention delivery and data collection will continue until November 2021. The results are expected to be published by May 2022.

Conclusions

This is among the first trials to incorporate health coaches, clinical pharmacists, and mHealth technologies to increase access to diabetes support among urban African-Americans and Latinos to achieve therapeutic goals.

International Registered Report Identifier (IRRID)

DERR1-10.2196/17170

Racial and Ethnic Differences in Metabolic Disease in Adolescents With Obesity and Polycystic Ovary Syndrome

Context

Polycystic ovary syndrome (PCOS) is common and associated with metabolic syndrome. In the general population, metabolic disease varies by race and ethnicity.

Objective

This work aimed to examine in depth the interaction of race and ethnicity with PCOS-related metabolic disease in adolescent youth.

Methods

A secondary analysis was conducted of data from girls (age 12-21 years) with overweight or obesity (> 90 body mass index [BMI] percentile) and PCOS. Measurements included fasting hormone and metabolic measures, a 2-hour oral glucose tolerance test (OGTT), and magnetic resonance imaging for hepatic fat. Groups were categorized by race or ethnicity.

Results

Participants included 39 non-Hispanic White (NHW, age 15.7 ± 0.2 years; BMI 97.7 ± 0.2 percentile), 50 Hispanic (HW, 15.2 ± 0.3 years; 97.9 ± 0.3 percentile), and 12 non-Hispanic Black (NHB, 16.0 ± 0.6 years; 98.6 ± 0.4 percentile) adolescents. Hepatic markers of insulin resistance were worse in NHW, including lower sex hormone-binding globulin and higher triglycerides over high-density lipoprotein cholesterol (TGs/HDL-C) ratio (P = .002 overall, HW vs NHB [P = .009] vs NHW [P = 0.020]), although homeostasis model assessment of estimated insulin resistance was worst in NHB (P = .010 overall, NHW vs NHB P = .014). Fasting and 2-hour OGTT glucose were not different between groups, although glycated hemoglobin A_1c (HbA_1c) was lowest in NHW (overall P < .001, NHW 5.2 ± 0.3 vs HW 5.5 ± 0.3 P < .001 vs 5.7 ± 0.4%, P < .001). The frequency of hepatic steatosis (HW 62%, NHW 42%, NHB 25%, P = .032); low HDL-C < 40 mg/dL (HW 82%, NHW 61%, NHB 50%, P < .001) and prediabetes HbA_1c 5.7% to 6.4% (NHB 50%, HW 36%, NHW 5%, P < .001) were different between the groups.

Conclusion

Adolescents with PCOS appear to show similar racial and ethnic variation to the general population in terms of metabolic disease components.

Toward Understanding Social Needs Among Primary Care Patients With Uncontrolled Diabetes

Introduction/Objectives:

Uncontrolled diabetes can lead to major health complications, and significantly contributes to diabetes-related morbidity, mortality, and healthcare costs. Few studies have examined the relationship between unmet social needs and diabetes control among predominantly Black and Hispanic patient populations.

Methods:

In a large urban hospital system in the Bronx, NY, 5846 unique patients with diabetes seen at a primary care visit between April 2018 and December 2019 completed a social needs screener. Measures included diabetes control (categorized as Hemoglobin (Hb) A1c <9.0 as controlled and Hb A1C ≥9.0 as uncontrolled), social needs (10-item screen), and demographic covariates, including age, sex, race/ethnicity, insurance status, percentage of block-group poverty, patient’s preferred language, and the Elixhauser Comorbidity Index.

Results:

Twenty-two percent (22%) of the patient sample had at least 1 unmet social need, and the most prevalent unmet social needs were housing issues (including housing quality and insecurity), food insecurity, and lack of healthcare transportation. Logistic regression analysis showed a significant relationship between social needs and uncontrolled diabetes, with more social needs indicating a greater likelihood of uncontrolled diabetes (Adjusted Odds Ratio (AOR) for ≥3 needs: 1.59, 95% CI: 1.26, 2.00). Of the patients with most frequently occurring unmet social needs, lack of healthcare transportation (AOR: 1.54, 95% CI: 1.22, 1.95) and food insecurity (AOR: 1.50, 95% CI: 1.19, 1.89) had the greatest likelihood of having uncontrolled diabetes, after adjusting for covariates.

Conclusion:

Unmet social needs appear to be linked to a greater likelihood of uncontrolled diabetes. Implications for healthcare systems to screen and address social needs for patients with diabetes are discussed.

Advances in Pancreatic Islet Transplantation Sites for the Treatment of Diabetes

Diabetes is a complex disease that affects over 400 million people worldwide. The life-long insulin injections and continuous blood glucose monitoring required in type 1 diabetes (T1D) represent a tremendous clinical and economic burdens that urges the need for a medical solution. Pancreatic islet transplantation holds great promise in the treatment of T1D; however, the difficulty in regulating post-transplantation immune reactions to avoid both allogenic and autoimmune graft rejection represent a bottleneck in the field of islet transplantation. Cell replacement strategies have been performed in hepatic, intramuscular, omentum, and subcutaneous sites, and have been performed in both animal models and human patients. However more optimal transplantation sites and methods of improving islet graft survival are needed to successfully translate these studies to a clinical relevant therapy. In this review, we summarize the current progress in the field as well as methods and sites of islet transplantation, including stem cell-derived functional human islets. We also discuss the contribution of immune cells, vessel formation, extracellular matrix, and nutritional supply on islet graft survival. Developing new transplantation sites with emerging technologies to improve islet graft survival and simplify immune regulation will greatly benefit the future success of islet cell therapy in the treatment of diabetes.

Immune Protection of Stem Cell-Derived Islet Cell Therapy for Treating Diabetes

Insulin injection is currently the main therapy for type 1 diabetes (T1D) or late stage of severe type 2 diabetes (T2D). Human pancreatic islet transplantation confers a significant improvement in glycemic control and prevents life-threatening severe hypoglycemia in T1D patients. However, the shortage of cadaveric human islets limits their therapeutic potential. In addition, chronic immunosuppression, which is required to avoid rejection of transplanted islets, is associated with severe complications, such as an increased risk of malignancies and infections. Thus, there is a significant need for novel approaches to the large-scale generation of functional human islets protected from autoimmune rejection in order to ensure durable graft acceptance without immunosuppression. An important step in addressing this need is to strengthen our understanding of transplant immune tolerance mechanisms for both graft rejection and autoimmune rejection. Engineering of functional human pancreatic islets that can avoid attacks from host immune cells would provide an alternative safe resource for transplantation therapy. Human pluripotent stem cells (hPSCs) offer a potentially limitless supply of cells because of their self-renewal ability and pluripotency. Therefore, studying immune tolerance induction in hPSC-derived human pancreatic islets will directly contribute toward the goal of generating a functional cure for insulin-dependent diabetes. In this review, we will discuss the current progress in the immune protection of stem cell-derived islet cell therapy for treating diabetes.