The association of insulin responses and insulin sensitivity with cognition in adults with pre-diabetes: The Diabetes Prevention Program Outcomes Study.

OBJECTIVE: Dysglycemia is a significant risk factor for cognitive impairment. However, which pathophysiologic determinant(s) of dysglycemia, impaired insulin sensitivity (ISens) or the islet ß-cell's response (IResp), contribute to poorer cognitive function, independent of dysglycemia is not established. Among 1052 adults with pre-diabetes from the Diabetes Prevention Program Outcomes Study (DPPOS), we investigated the relationship between IResp, ISens and cognitive function. RESEARCH DESIGN AND METHODS: IResp was estimated by the insulinogenic index (IGI; pmol/mmol) and ISens as 1/fasting insulin from repeated annual oral glucose tolerance tests. The mean IResp and mean ISens were calculated over approximately 12 years of follow-up. Verbal learning (Spanish-English Verbal Learning Test [SEVLT]) and executive function (Digital Symbol Substitution Test [DSST]) were assessed at the end of the follow-up period. Linear regression models were run for each cognitive outcome and were adjusted for dysglycemia and other factors. RESULTS: Higher IResp was associated with poorer performance on the DSST (-0.69 points per 100 unit increase in IGI, 95 % CI: -1.37, -0.01). ISens was not associated with DSST, nor were IResp or ISens associated with performance on the SEVLT. CONCLUSIONS: These results suggest that a greater ß-cell response in people at high risk for type 2 diabetes is associated with poorer executive function, independent of dysglycemia and ISens.

Increased genetic risk for ß-cell failure is associated with ß-cell function decline in people with prediabetes.

Partitioned polygenic scores (pPS) have been developed to capture pathophysiologic processes underlying type 2 diabetes (T2D). We investigated the influence of T2D pPS on diabetes-related traits and T2D incidence in the Diabetes Prevention Program. We generated five T2D pPS (ß-cell, proinsulin, liver/lipid, obesity, lipodystrophy) in 2,647 participants randomized to intensive lifestyle, metformin or placebo arms. Associations were tested using general linear models and Cox regression adjusted for age, sex, and principal components. Sensitivity analyses included adjustment for BMI. Higher ß-cell pPS was associated with lower insulinogenic index and corrected insulin response at one year follow-up adjusted for baseline measures (effect per pPS standard deviation (SD) -0.04, P=9.6 x 10-7; -8.45 uU/mg, P=5.6 x 10-6, respectively) and with increased diabetes incidence adjusted for BMI at nominal significance (HR 1.10 per SD, P=0.035). The liver/lipid pPS was associated with reduced one-year baseline-adjusted triglyceride levels (effect per SD -4.37, P=0.001). There was no significant interaction between T2D pPS and randomized groups. The remaining pPS were associated with baseline measures only. We conclude that despite interventions for diabetes prevention, participants with a high genetic burden of the ß-cell cluster pPS had worsening in measures of ß-cell function.

Within and post-trial effects of an intensive lifestyle intervention on kidney disease in adults with overweight or obesity and type 2 diabetes mellitus: a secondary analysis of the Look AHEAD clinical trial.

INTRODUCTION: The Look AHEAD randomized clinical trial reported that an 8-year intensive lifestyle intervention (ILI) compared with diabetes support and education (DSE) in adults aged 45-76 years with type 2 diabetes and overweight/obesity delayed kidney disease progression. Here, we report long-term post-intervention follow-up for the trial's secondary outcome of kidney disease. RESEARCH DESIGN AND METHODS: We examined effects of ILI (n=2570) versus DSE (n=2575) on decline in estimated glomerular filtration rate (eGFR) to <45 mL/min/1.73 m2 or need for kidney replacement therapy (KRT: dialysis or kidney transplant) during intervention and post-intervention follow-up (median 15.6 years overall). RESULTS: Incidence of eGFR <45 mL/min/1.73 m2 was lower in ILI during the intervention (HR=0.80, 95% CI=0.66 to 0.98) but not post-intervention (HR=1.03, 0.86 to 1.23) or overall (HR=0.92, 0.80 to 1.04). There were no significant treatment group differences in KRT. In prespecified subgroup analyses, age×treatment interactions were significant over total follow-up: p=0.001 for eGFR <45 mL/min/1.73 m2 and p=0.01 for KRT. The 2205 participants aged >60 years at baseline had benefit in both kidney outcomes during intervention and overall (HR=0.75, 0.62 to 0.90 for eGFR <45 mL/min/1.73 m2; HR=0.62, 0.43 to 0.91 for KRT). The absolute treatment effects were greater post-intervention: ILI reduced the rate of eGFR <45 mL/min/1.73 m2 by 0.46 and 0.76 cases/100 person-years during and post-intervention, respectively; and reduced KRT by 0.15 and 0.21 cases/100 person-years. The younger participants experienced no such post-intervention benefits. CONCLUSIONS: ILI reduced kidney disease progression during and following the active intervention in persons aged ≥60 years. ILI should be considered for reducing kidney disease incidence in older persons with type 2 diabetes.

Prevalence of Distal Symmetrical Polyneuropathy by Diabetes Prevention Program Treatment Group, Diabetes Status, Duration of Diabetes, and Cumulative Glycemic Exposure.

OBJECTIVE: To assess associations between distal symmetric polyneuropathy (DSPN) and Diabetes Prevention Program (DPP) treatment groups, diabetes status or duration, and cumulative glycemic exposure approximately 21 years after DPP randomization. RESEARCH DESIGN AND METHODS: In the DPP, 3,234 adults ≥25 years old at high risk for diabetes were randomized to an intensive lifestyle (ILS), metformin, or placebo intervention to prevent diabetes. After the DPP ended, 2,779 joined the Diabetes Prevention Program Outcomes Study (DPPOS). Open-label metformin was continued, placebo was discontinued, ILS was provided in the form of semiannual group-based classes, and all participants were offered quarterly lifestyle classes. Symptoms and signs of DSPN were assessed in 1,792 participants at DPPOS year 17. Multivariable logistic regression models were used to evaluate DSPN associations with treatment group, diabetes status/duration, and cumulative glycemic exposure. RESULTS: At 21 years after DPP randomization, 66% of subjects had diabetes. DSPN prevalence did not differ by initial DPP treatment assignment (ILS 21.5%, metformin 21.5%, and placebo 21.9%). There was a significant interaction between treatment assignment to ILS and age (P < 0.05) on DSPN. At DPPOS year 17, the odds ratio for DSPN in comparison with ILS with placebo was 17.4% (95% CI 3.0, 29.3) lower with increasing 5-year age intervals. DSPN prevalence was slightly lower for those at risk for diabetes (19.6%) versus those with diabetes (22.7%) and was associated with longer diabetes duration and time-weighted HbA1c (P values <0.001). CONCLUSIONS: The likelihood of DSPN was similar across DPP treatment groups but higher for those with diabetes, longer diabetes duration, and higher cumulative glycemic exposure. ILS may have long-term benefits on DSPN for older adults.

Epistasis Between HLA-DRB1*16:02:01 and SLC16A11 T-C-G-T-T Reduces Odds for Type 2 Diabetes in Southwest American Indians.

We sought to identify genetic/immunologic contributors of type 2 diabetes (T2D) in an indigenous American community by genotyping all study participants for both high-resolution HLA-DRB1 alleles and SLC16A11 to test their risk and/or protection for T2D. These genes were selected based on independent reports that HLA-DRB1*16:02:01 is protective for T2D and that SLC16A11 associates with T2D in individuals with BMI <35 kg/m2. Here, we test the interaction of the two loci with a more complete data set and perform a BMI sensitivity test. We defined the risk protection haplotype of SLC16A11, T-C-G-T-T, as allele 2 of a diallelic genetic model with three genotypes, SLC16A11*11, *12, and *22, where allele 1 is the wild type. Both earlier findings were confirmed. Together in the same logistic model with BMI ≥35 kg/m2, DRB1*16:02:01 remains protective (odds ratio [OR] 0.73), while SLC16A11 switches from risk to protection (OR 0.57 [*22] and 0.78 [*12]); an added interaction term was statistically significant (OR 0.49 [*12]). Bootstrapped (b = 10,000) statistical power of interaction, 0.4801, yielded a mean OR of 0.43. Sensitivity analysis demonstrated that the interaction is significant in the BMI range of 30-41 kg/m2. To investigate the epistasis, we used the primary function of the HLA-DRB1 molecule, peptide binding and presentation, to search the entire array of 15-mer peptides for both the wild-type and ancient human SLC16A11 molecules for a pattern of strong binding that was associated with risk and protection for T2D. Applying computer binding algorithms suggested that the core peptide at SLC16A11 D127G, FSAFASGLL, might be key for moderating risk for T2D with potential implications for type 1 diabetes.

Preventing diabetes in Latino families: A protocol for a randomized control trial.

BACKGROUND: Latino families are disproportionately affected by type 2 diabetes (T2D) and lifestyle intervention is the first-line approach for preventing T2D. The purpose of this study is to test the efficacy of a culturally-grounded lifestyle intervention that prioritizes health promotion and diabetes prevention for Latino families. The intervention is guided by a novel Family Diabetes Prevention Model, leveraging the family processes of engagement, empowerment, resilience, and cohesion to orient the family system towards health. METHOD: Latino families (N = 132) will be recruited and assessed for glucose tolerance as measured by an Oral Glucose Tolerance Test (OGTT) and General and Weight-Specific Quality of Life (QoL) at baseline, four months, and 12 months. All members of the household age 10 and over will be invited to participate. Families will be randomized to the intervention group or a control group (2:1). The 16-week intervention includes weekly nutrition and wellness classes delivered by bilingual, bicultural Registered Dietitians and community health educators at a local YMCA along with two days/week of supervised physical activity classes and a third day of unsupervised physical activity. Control families will meet with a physician and a Registered Dietitian to discuss the results of their metabolic testing and recommend lifestyle changes. We will test the efficacy of a family-focused diabetes prevention intervention for improving glucose tolerance and increasing QoL and test for mediators and moderators of long-term changes. CONCLUSION: This study will provide much needed data on the efficacy of a family-focused Diabetes Prevention Program among high-risk Latino families.

Effects of metformin and intensive lifestyle interventions on the incidence of kidney disease in adults in the DPP/DPPOS.

AIMS: We analyzed the incidence of kidney disease in the Diabetes Prevention Program Outcomes Study (DPPOS) by originally randomized treatment group assignment: Intensive Lifestyle (ILS), Metformin (MET) or Placebo (PLB). METHODS: The current analyses used a time-to-event approach in which the primary outcome was kidney disease, ascertained as urine albumin-to-creatinine ratio (ACR) ≥ 3.39 mg/mmol (30 mg/g) or eGFR <45 mL/min/1.73m2, with confirmation required at the next visit, or adjudicated end-stage kidney disease (ESKD). RESULTS: At a median of 21 years following randomization in DPP, diabetes development was reduced in both the ILS (HR 0.73 [95%CI = 0.62, 0.85]) and MET groups (HR 0.85 [0.73, 0.99]) compared to the PLB group. Although risk for developing the primary kidney disease outcome was higher among those with incident diabetes compared to those without (HR 1.81 [1.43, 2.30]), it did not differ by intervention groups (ILS vs. PLB 1.02 (0.81, 1.29); MET vs. PLB 1.08 (0.86, 1.35). There was a non-significant metformin by age interaction (p = 0.057), with metformin being beneficial for kidney disease in the younger but potentially harmful in the older participants. CONCLUSIONS: Development of kidney disease was increased in participants who developed diabetes but did not differ by original treatment group assignment. CLINICAL TRIAL REGISTRATIONS: Diabetes Prevention Program (DPP) Clinical trial reg. no. NCT00004992 DPP Outcomes Study (DPPOS) Clinical trial reg. no. NCT0038727.

New-Onset Diabetes After COVID-19.

There is evidence suggesting that infection with SARS-CoV-2 can lead to several long-term sequelae including diabetes. This mini-review examines the rapidly evolving and conflicting literature on new-onset diabetes after COVID-19, which we term NODAC. We searched PubMed, MEDLINE, and medRxiv from inception until December 1, 2022, using Medical Subject Headings (MeSH) terms and free text words including "COVID-19," "SARS-CoV-2," "diabetes," "hyperglycemia," "insulin resistance," and "pancreatic ß-cell." We also supplemented searches by examining reference lists from retrieved articles. Current evidence suggests that COVID-19 increases the risk of developing diabetes, but the attributable risk is uncertain because of limitations of study designs and the evolving nature of the pandemic, including new variants, widespread population exposure to the virus, diagnostic options for COVID-19, and vaccination status. The etiology of diabetes after COVID-19 is likely multifactorial and includes factors associated with host characteristics (eg, age), social determinants of health (eg, deprivation index), and pandemic-related effects both at the personal (eg, psychosocial stress) and the societal-community level (eg, containment measures). COVID-19 may have direct and indirect effects on pancreatic ß-cell function and insulin sensitivity related to the acute infection and its treatment (eg, glucocorticoids); autoimmunity; persistent viral residency in multiple organs including adipose tissue; endothelial dysfunction; and hyperinflammatory state. While our understanding of NODAC continues to evolve, consideration should be given for diabetes to be classified as a post-COVID syndrome, in addition to traditional classifications of diabetes (eg, type 1 or type 2), so that the pathophysiology, natural history, and optimal management can be studied.

Indices of hepatic steatosis and fibrosis in prediabetes and association with diabetes development in the vitamin D and type 2 diabetes study.

AIMS: Non-alcoholic fatty liver disease (NAFLD) is a common comorbidity that leads to poor outcomes in people at high risk for development of type 2 diabetes (T2D). Vitamin D is a possible mediator. In the vitamin D and type 2 diabetes study (D2d), we investigated the relationship of baseline indices of NAFLD with incident T2D and whether the effect of vitamin D on diabetes was modified by NAFLD. METHODS: Cross-sectional associations of indices of NAFLD with glycemia and vitamin D status were assessed in 3972 individuals screened for the D2d study. In those with prediabetes randomized to vitamin D or placebo (n = 2423), we examined longitudinal associations of NAFLD indices with incident T2D. We used validated non-invasive scores to assess steatosis [(hepatic steatosis index (HSI); NAFLD-liver fat score (NAFLD-LFS)] and advanced fibrosis [fibrosis-4 (FIB-4) index; AST to Platelet Ratio Index (APRI)]. RESULTS: Eighty-five percent of screened participants had likely steatosis by HSI and 71 % by NAFLD-LFS; 3 % were likely to have advanced fibrosis by FIB-4 and 1.2 % by APRI. FIB-4 indicated that 20.4 % of individuals require further follow up to assess liver health. Steatosis and fibrosis scores were higher among participants with worse glycemia. The NAFLD-LFS and APRI predicted development of diabetes (hazard ratios [95%CI] 1.35 [1.07, 1.70]; P = 0.012) and 2.36 (1.23, 4.54; P = 0.010), respectively). The effect of vitamin D on diabetes risk was not modified by baseline NAFLD indices. Individuals with likely steatosis had a smaller increase in serum 25-hydroxyvitamin D level in response to vitamin D than those without steatosis. CONCLUSIONS: The predicted high prevalence of steatosis, the need for further fibrosis workup, and the relationship between liver health and incident T2D suggest that routine screening with clinically accessible scores may be an important strategy to reduce disease burden.

Adolescent Growth Spurt and Type 2 Diabetes Risk in Southwestern American Indians.

Early puberty onset is associated with higher risk of diabetes, but most studies have not accounted for childhood factors that may confound the association. Using data from a study conducted in an Indigenous community in Arizona (1965-2007), we examined associations of timing and velocity of the adolescent growth spurt with type 2 diabetes, and whether these associations are mediated by childhood body mass index and insulinemia. Adolescent growth parameters were derived from the Preece-Baines growth model, a parametric growth curve fitted to longitudinal height data, for 861 participants with height measurements spanning the whole period of growth. In males, older age at take-off, age at peak velocity, and age at maturation were associated with decreased prevalence of diabetes (odds ratio (OR) = 0.43 per year, 95% confidence interval (CI): 0.27, 0.69; OR = 0.50, 95% CI: 0.35, 0.72; OR = 0.58, 95% CI: 0.41, 0.83, respectively), while higher velocity at take-off was associated with increased risk (OR = 3.47 per cm/year, 95% CI: 1.87, 6.42) adjusting for age, birth year, and maternal diabetes. Similar results were observed with incident diabetes. Our findings suggest that an early and accelerated adolescent growth spurt is a risk factor for diabetes, at least in males. These associations are only partially explained by measures of adiposity and insulinemia.

The utility of a type 2 diabetes polygenic score in addition to clinical variables for prediction of type 2 diabetes incidence in birth, youth and adult cohorts in an Indigenous study population.

AIMS/HYPOTHESIS: There is limited information on how polygenic scores (PSs), based on variants from genome-wide association studies (GWASs) of type 2 diabetes, add to clinical variables in predicting type 2 diabetes incidence, particularly in non-European-ancestry populations. METHODS: For participants in a longitudinal study in an Indigenous population from the Southwestern USA with high type 2 diabetes prevalence, we analysed ten constructions of PS using publicly available GWAS summary statistics. Type 2 diabetes incidence was examined in three cohorts of individuals without diabetes at baseline. The adult cohort, 2333 participants followed from age ≥20 years, had 640 type 2 diabetes cases. The youth cohort included 2229 participants followed from age 5-19 years (228 cases). The birth cohort included 2894 participants followed from birth (438 cases). We assessed contributions of PSs and clinical variables in predicting type 2 diabetes incidence. RESULTS: Of the ten PS constructions, a PS using 293 genome-wide significant variants from a large type 2 diabetes GWAS meta-analysis in European-ancestry populations performed best. In the adult cohort, the AUC of the receiver operating characteristic curve for clinical variables for prediction of incident type 2 diabetes was 0.728; with the PS, 0.735. The PS's HR was 1.27 per SD (p=1.6 × 10-8; 95% CI 1.17, 1.38). In youth, corresponding AUCs were 0.805 and 0.812, with HR 1.49 (p=4.3 × 10-8; 95% CI 1.29, 1.72). In the birth cohort, AUCs were 0.614 and 0.685, with HR 1.48 (p=2.8 × 10-16; 95% CI 1.35, 1.63). To further assess the potential impact of including PS for assessing individual risk, net reclassification improvement (NRI) was calculated: NRI for the PS was 0.270, 0.268 and 0.362 for adult, youth and birth cohorts, respectively. For comparison, NRI for HbA1c was 0.267 and 0.173 for adult and youth cohorts, respectively. In decision curve analyses across all cohorts, the net benefit of including the PS in addition to clinical variables was most pronounced at moderately stringent threshold probability values for instituting a preventive intervention. CONCLUSIONS/INTERPRETATION: This study demonstrates that a European-derived PS contributes significantly to prediction of type 2 diabetes incidence in addition to information provided by clinical variables in this Indigenous study population. Discriminatory power of the PS was similar to that of other commonly measured clinical variables (e.g. HbA1c). Including type 2 diabetes PS in addition to clinical variables may be clinically beneficial for identifying individuals at higher risk for the disease, especially at younger ages.

Identification of Genetic Variation Influencing Metformin Response in a Multiancestry Genome-Wide Association Study in the Diabetes Prevention Program (DPP).

Genome-wide significant loci for metformin response in type 2 diabetes reported elsewhere have not been replicated in the Diabetes Prevention Program (DPP). To assess pharmacogenetic interactions in prediabetes, we conducted a genome-wide association study (GWAS) in the DPP. Cox proportional hazards models tested associations with diabetes incidence in the metformin (MET; n = 876) and placebo (PBO; n = 887) arms. Multiple linear regression assessed association with 1-year change in metformin-related quantitative traits, adjusted for baseline trait, age, sex, and 10 ancestry principal components. We tested for gene-by-treatment interaction. No significant associations emerged for diabetes incidence. We identified four genome-wide significant variants after correcting for correlated traits (P < 9 × 10-9). In the MET arm, rs144322333 near ENOSF1 (minor allele frequency [MAF]AFR = 0.07; MAFEUR = 0.002) was associated with an increase in percentage of glycated hemoglobin (per minor allele, ß = 0.39 [95% CI 0.28, 0.50]; P = 2.8 × 10-12). rs145591055 near OMSR (MAF = 0.10 in American Indians) was associated with weight loss (kilograms) (per G allele, ß = -7.55 [95% CI -9.88, -5.22]; P = 3.2 × 10-10) in the MET arm. Neither variant was significant in PBO; gene-by-treatment interaction was significant for both variants [P(G×T) < 1.0 × 10-4]. Replication in individuals with diabetes did not yield significant findings. A GWAS for metformin response in prediabetes revealed novel ethnic-specific associations that require further investigation but may have implications for tailored therapy.

Association of Metformin With the Development of Age-Related Macular Degeneration.

Importance: Age-related macular degeneration (AMD) is a leading cause of blindness with no treatment available for early stages. Retrospective studies have shown an association between metformin and reduced risk of AMD. Objective: To investigate the association between metformin use and age-related macular degeneration (AMD). Design, Setting, and Participants: The Diabetes Prevention Program Outcomes Study is a cross-sectional follow-up phase of a large multicenter randomized clinical trial, Diabetes Prevention Program (1996-2001), to investigate the association of treatment with metformin or an intensive lifestyle modification vs placebo with preventing the onset of type 2 diabetes in a population at high risk for developing diabetes. Participants with retinal imaging at a follow-up visit 16 years posttrial (2017-2019) were included. Analysis took place between October 2019 and May 2022. Interventions: Participants were randomly distributed between 3 interventional arms: lifestyle, metformin, and placebo. Main Outcomes and Measures: Prevalence of AMD in the treatment arms. Results: Of 1592 participants, 514 (32.3%) were in the lifestyle arm, 549 (34.5%) were in the metformin arm, and 529 (33.2%) were in the placebo arm. All 3 arms were balanced for baseline characteristics including age (mean [SD] age at randomization, 49 [9] years), sex (1128 [71%] male), race and ethnicity (784 [49%] White), smoking habits, body mass index, and education level. AMD was identified in 479 participants (30.1%); 229 (14.4%) had early AMD, 218 (13.7%) had intermediate AMD, and 32 (2.0%) had advanced AMD. There was no significant difference in the presence of AMD between the 3 groups: 152 (29.6%) in the lifestyle arm, 165 (30.2%) in the metformin arm, and 162 (30.7%) in the placebo arm. There was also no difference in the distribution of early, intermediate, and advanced AMD between the intervention groups. Mean duration of metformin use was similar for those with and without AMD (mean [SD], 8.0 [9.3] vs 8.5 [9.3] years; P = .69). In the multivariate models, history of smoking was associated with increased risks of AMD (odds ratio, 1.30; 95% CI, 1.05-1.61; P = .02). Conclusions and Relevance: These data suggest neither metformin nor lifestyle changes initiated for diabetes prevention were associated with the risk of any AMD, with similar results for AMD severity. Duration of metformin use was also not associated with AMD. This analysis does not address the association of metformin with incidence or progression of AMD.

Effects of the ABCC8 R1420H loss-of-function variant on beta-cell function, diabetes incidence, and retinopathy.

INTRODUCTION: The ABCC8 gene regulates insulin secretion and plays a critical role in glucose homeostasis. The effects of an ABCC8 R1420H loss-of-function variant on beta-cell function, incidence of type 2 diabetes, and age-at-onset, prevalence, and progression of diabetes complications were assessed in a longitudinal study in American Indians. RESEARCH DESIGN AND METHODS: We analyzed beta-cell function through the relationship between insulin secretion and insulin sensitivity in members of this population without diabetes aged ≥5 years using standard major axis regression. We used hierarchical logistic regression models to study cross-sectional associations with diabetes complications including increased albuminuria (albumin-to-creatinine ratio (ACR) ≥30 mg/g), severe albuminuria (ACR ≥300 mg/g), reduced estimated glomerular filtration rate (eGFR <60 mL/min/1.73 m2), and retinopathy. This study included 7675 individuals (254 variant carriers) previously genotyped for the R1420H with available phenotypic data and with a median follow-up time of 13.5 years (IQR 4.5-26.8). RESULTS: Variant carriers had worse beta-cell function than non-carriers (p=0.0004; on average estimated secretion was 22% lower, in carriers), in children and adults, with no difference in insulin sensitivity (p=0.50). At any body mass index and age before 35 years, carriers had higher type 2 diabetes incidence. This variant did not associate with prevalence of increased albuminuria (OR 0.87, 95% CI 0.66 to 1.16), severe albuminuria (OR 0.96, 95% CI 0.55 to 1.68), or reduced eGFR (OR 0.44, 95% CI 0.18 to 1.06). By contrast, the variant significantly associated with higher retinopathy prevalence (OR 1.74, 95% CI 1.19 to 2.53) and this association was only partially mediated (<11%) by glycemia, duration of diabetes, risk factors of retinopathy, or insulin use. Retinopathy prevalence in carriers was higher regardless of diabetes presence. CONCLUSIONS: The ABCC8 R1420H variant is associated with increased risks of diabetes and of retinopathy, which may be partially explained by higher glycemia levels and worse beta-cell function.

Risk Factors for the Development of Retinopathy in Prediabetes and Type 2 Diabetes: The Diabetes Prevention Program Experience.

OBJECTIVE: To determine glycemic and nonglycemic risk factors that contribute to the presence of diabetic retinopathy (DR) before and after the onset of type 2 diabetes (T2D). RESEARCH DESIGN AND METHODS: During the Diabetes Prevention Program (DPP) and DPP Outcome Study (DPPOS), we performed fundus photography over time in adults at high risk for developing T2D, including after they developed diabetes. Fundus photographs were graded using the Early Treatment Diabetic Retinopathy Study (ETDRS) grading system, with DR defined as typical lesions of DR (microaneurysms, exudates, hemorrhage, or worse) in either eye. RESULTS: By DPPOS year 16 (∼20 years after random assignment into DPP), 24% of 1,614 participants who had developed T2D and 14% of 885 who remained without diabetes had DR. In univariate analyses, using results from across the entire duration of follow-up, American Indian race was associated with less frequent DR compared with non-Hispanic White (NHW) race, and higher HbA1c, fasting and 2-h plasma glucose levels during an oral glucose tolerance test, weight, and history of hypertension, dyslipidemia, and smoking, but not treatment group assignment, were associated with more frequent DR. On multivariate analysis, American Indian race was associated with less DR compared with NHW (odds ratio [OR] 0.36, 95% CI 0.20-0.66), and average HbA1c was associated with more DR (OR 1.92, 95% CI 1.46-1.74 per SD [0.7%] increase in HbA1c). CONCLUSIONS: DR may occur in adults with prediabetes and early in the course of T2D. HbA1c was an important risk factor for the development of DR across the entire glycemic range from prediabetes to T2D.

Effects of a Diabetes Prevention Program on Type 2 Diabetes Risk Factors and Quality of Life Among Latino Youths With Prediabetes: A Randomized Clinical Trial.

Importance: Latino youths are disproportionately impacted by prediabetes and type 2 diabetes (T2D). Lifestyle intervention is the first-line approach for preventing or delaying T2D among adults with prediabetes. Objective: To assess the efficacy of a diabetes prevention program among Latino youths aged 12 to 16 years with prediabetes. Design, Setting, and Participants: This 2-group parallel randomized clinical trial with 2:1 randomization assessed a lifestyle intervention against usual care among Latino youths with prediabetes and obesity with 6- and 12-month follow-up. The study was conducted at YMCA facilities in Phoenix, Arizona from May 2016 to March 2020. Intervention: Participants were randomized to lifestyle intervention (INT) or usual care control (UCC). The 6-month INT included 1 d/wk of nutrition and health education and 3 d/wk of physical activity. UCC included 2 visits with a pediatric endocrinologist and a bilingual, bicultural registered dietitian to discuss diabetes risks and healthy lifestyle changes. Main Outcomes and Measures: Insulin sensitivity, glucose tolerance, and weight-specific quality of life (YQOL-W) at 6- and 12-month follow-up. Results: A total of 117 Latino youths (mean [SD] age, 14 [1] years; 47 [40.1%] girls) were included in the analysis. Overall, 79 were randomized to INT and 38 to UCC. At 6 months, the INT led to significant decreases in mean (SE) 2-hour glucose (baseline: 144 [3] mg/dL; 6 months: 132 [3] mg/dL; P = .002) and increases in mean (SE) insulin sensitivity (baseline: 1.9 [0.2]; 6 months: 2.6 [0.3]; P = .001) and YQOL-W (baseline: 75 [2]; 6 months: 80 [2]; P = .006), but these changes were not significantly different from UCC (2-hour glucose: mean difference, -7.2 mg/dL; 95% CI, -19.7 to 5.3 mg/dL; P for interaction = .26; insulin sensitivity: mean difference, 0.1; 95% CI, -0.7 to 0.9; P for interaction = .79; YQOL-W: mean difference, 6.3; 95% CI, -1.1 to 13.7; P for interaction = .10, respectively). Both INT (mean [SE], -15 mg/dL [4.9]; P = .002) and UCC (mean [SE], -15 mg/dL [5.4]; P = .005) had significant 12-month reductions in 2-hour glucose that did not differ significantly from each other (mean difference, -0.3; 95% CI, -14.5 to 14.1 mg/dL; P for interaction = .97). At 12 months, changes in mean (SE) insulin sensitivity in INT (baseline: 1.9 [0.2]; 12 months: 2.3 [0.2]; P = .06) and UCC (baseline: 1.9 [0.3]; 12 months: 2.0 [0.2]; P = .70) were not significantly different (mean difference, 0.3; 95% CI, -0.4 to 1.0; P for interaction = .37). At 12 months, YQOL-W was significantly increased in INT (basline: 75 [2]; 12 months: 82 [2]; P < .001) vs UCC (mean difference, 8.5; 95% CI, 0.8 to 16.2; P for interaction = .03). Conclusions and Relevance: In this randomized clinical trial, both INT and UCC led to similar changes in T2D risk factors among Latino youths with diabetes; however, YQOL-W was improved in INT compared with UCC. Diabetes prevention interventions that are effective in adults also appeared to be effective in high risk youths. Trial Registration: ClinicalTrials.gov Identifier: NCT02615353.

Weight Loss, Lifestyle Intervention, and Metformin Affect Longitudinal Relationship of Insulin Secretion and Sensitivity.

CONTEXT: Insulin secretion and sensitivity regulate glycemia, with inadequately compensated deficiencies leading to diabetes. OBJECTIVE: We investigated effects of weight loss, an intensive lifestyle intervention (ILS), and metformin on the relationship between insulin secretion and sensitivity using repository data from 2931 participants in the Diabetes Prevention Program clinical trial in adults at high risk of developing type 2 diabetes. METHODS: Insulin secretion and sensitivity were estimated from insulin and glucose concentrations in fasting and 30-minute postload serum samples at baseline and 1, 2, and 3 years after randomization, during the active intervention phase. The nonlinear relationship of secretion and sensitivity was evaluated by standardized major axis regression to account for variability in both variables. Insulin secretory demand and compensatory insulin secretion were characterized by distances along and away from the regression line, respectively. RESULTS: ILS and metformin decreased secretory demand while increasing compensatory insulin secretion, with greater effects of ILS. Improvements were directly related to weight loss; decreased weight significantly reduced secretory demand (b=-0.144 SD; 95% CI (-0.162, -0.125)/5 kg loss) and increased compensatory insulin secretion (b = 0.287 SD, 95% CI (0.261, 0.314)/5 kg loss). In time-dependent hazard models, increasing compensatory insulin secretion (hazard ratio [HR] = 0.166 per baseline SD, 95% CI 0.133, 0.206) and weight loss (HR = 0.710 per 5 kg loss, 95% CI 0.613, 0.819) predicted lower diabetes risk. CONCLUSION: Diabetes risk reduction was directly related to the amount of weight loss, an effect mediated by lowered insulin secretory demand (due to increased insulin sensitivity) coupled with improved compensatory insulin secretion.

Functional characterization of a novel p.Ser76Thr variant in IGFBP4 that associates with body mass index in American Indians.

Insulin-like growth factor binding protein 4 (IGFBP4) is involved in adipogenesis, and IGFBP4 null mice have decreased body fat through decreased PPAR-γ expression. In the current study, we assessed whether variation in the IGFBP4 coding region influences body mass index (BMI) in American Indians who are disproportionately affected by obesity. Whole exome sequence data from a population-based sample of 6779 American Indians with longitudinal measures of BMI were used to identify variation in IGFBP4 that associated with BMI. A novel variant that predicts a p.Ser76Thr in IGFBP4 (Thr-allele frequency = 0.02) was identified which associated with the maximum BMI measured during adulthood (BMI 39.8 kg/m2 for Thr-allele homozygotes combined with heterozygotes vs. 36.2 kg/m2 for Ser-allele homozygotes, ß = 6.7% per Thr-allele, p = 8.0 × 10-5, adjusted for age, sex, birth-year and the first five genetic principal components) and the maximum age- and sex-adjusted BMI z-score measured during childhood/adolescence (z-score 0.70 SD for Thr-allele heterozygotes vs. 0.32 SD for Ser-allele homozygotes, ß = 0.37 SD per Thr-allele, p = 8.8 × 10-6). In vitro functional studies showed that IGFBP4 with the Thr-allele (BMI-increasing) had a 55% decrease (p = 0.0007) in FOXO-induced transcriptional activity, reflecting increased activation of the PI3K/AKT pathway mediated through increased IGF signaling. Over-expression and knock-down of IGFBP4 in OP9 cells during differentiation showed that IGFBP4 upregulates adipogenesis through PPARγ, CEBPα, AGPAT2 and SREBP1 expression. We propose that this American Indian specific variant in IGFBP4 affects obesity via an increase of IGF signaling.

Effects of Long-term Metformin and Lifestyle Interventions on Cardiovascular Events in the Diabetes Prevention Program and Its Outcome Study.

BACKGROUND: Lifestyle intervention and metformin have been shown to prevent diabetes; however, their efficacy in preventing cardiovascular disease associated with the development of diabetes is unclear. We examined whether these interventions reduced the incidence of major cardiovascular events over a 21-year median follow-up of participants in the DPP trial (Diabetes Prevention Program) and DPPOS (Diabetes Prevention Program Outcomes Study). METHODS: During DPP, 3234 participants with impaired glucose tolerance were randomly assigned to metformin 850 mg twice daily, intensive lifestyle or placebo, and followed for 3 years. During the next 18-year average follow-up in DPPOS, all participants were offered a less intensive group lifestyle intervention, and unmasked metformin was continued in the metformin group. The primary outcome was the first occurrence of nonfatal myocardial infarction, stroke, or cardiovascular death adjudicated by standard criteria. An extended cardiovascular outcome included the primary outcome or hospitalization for heart failure or unstable angina, coronary or peripheral revascularization, coronary heart disease diagnosed by angiography, or silent myocardial infarction by ECG. ECGs and cardiovascular risk factors were measured annually. RESULTS: Neither metformin nor lifestyle intervention reduced the primary outcome: metformin versus placebo hazard ratio 1.03 (95% CI, 0.78-1.37; P = 0.81) and lifestyle versus placebo hazard ratio 1.14 (95% CI, 0.87-1.50; P = 0.34). Risk factor adjustment did not change these results. No effect of either intervention was seen on the extended cardiovascular outcome. CONCLUSIONS: Neither metformin nor lifestyle reduced major cardiovascular events in DPPOS over 21 years despite long-term prevention of diabetes. Provision of group lifestyle intervention to all, extensive out-of-study use of statin and antihypertensive agents, and reduction in the use of study metformin together with out-of-study metformin use over time may have diluted the effects of the interventions. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifiers: DPP (NCT00004992) and DPPOS (NCT00038727).

Weight Change During the Postintervention Follow-up of Look AHEAD.

OBJECTIVE: Patients with type 2 diabetes are encouraged to lose weight, but excessive weight loss in older adults may be a marker of poor health and subsequent mortality. We examined weight change during the postintervention period of Look AHEAD, a randomized trial comparing intensive lifestyle intervention (ILI) with diabetes support and education (DSE) (control) in overweight/obese individuals with type 2 diabetes and sought to identify predictors of excessive postintervention weight loss and its association with mortality. RESEARCH DESIGN AND METHODS: These secondary analyses compared postintervention weight change (year 8 to final visit; median 16 years) in ILI and DSE in 3,999 Look AHEAD participants. Using empirically derived trajectory categories, we compared four subgroups: weight gainers (n = 307), weight stable (n = 1,561), steady losers (n = 1,731), and steep losers (n = 380), on postintervention mortality, demographic variables, and health status at randomization and year 8. RESULTS: Postintervention weight change averaged -3.7 ± 9.5%, with greater weight loss in the DSE than the ILI group. The steep weight loss trajectory subgroup lost on average 17.7 ± 6.6%; 30% of steep losers died during postintervention follow-up versus 10-18% in other trajectories (P < 0001). The following variables distinguished steep losers from weight stable: baseline, older, longer diabetes duration, higher BMI, and greater multimorbidity; intervention, randomization to control group and less weight loss in years 1-8; and year 8, higher prevalence of frailty, multimorbidity, and depressive symptoms and lower use of weight control strategies. CONCLUSIONS: Steep weight loss postintervention was associated with increased risk of mortality. Older individuals with longer duration of diabetes and multimorbidity should be monitored for excessive unintentional weight loss.