Insulin resistance before type 2 diabetes onset is associated with increased risk of albuminuria after diabetes onset: A prospective cohort study.

AIM: Reduced renal insulin signalling is implicated in the pathogenesis of albuminuria. We sought to investigate whether insulin action and secretion, measured before diabetes onset, are associated with the development of albuminuria after diabetes onset. MATERIALS AND METHODS: Baseline body composition, insulin sensitivity by hyperinsulinaemic-euglycaemic clamp at submaximal and maximal insulin stimulation (240 and 2400 pmol/m2/min; M-low and M-high), and insulin secretion by intravenous glucose tolerance test [acute insulin response (AIR)] were measured in 170 Southwestern Indigenous American adults who subsequently developed diabetes. After diabetes onset and during the median follow-up of 13.6 years, 81 participants (48%) developed albuminuria (urine albumin-to-creatinine ratio ≥30 mg/g). Separate associations of M-low, M-high and AIR (per 1-SD change) with the risk of albuminuria were assessed by Cox regression models adjusted for age, sex and body fat (%). RESULTS: Participants who developed albuminuria were of similar age (26.4 ± 5.4 vs. 27.5 ± 6.1 years), sex (46% vs. 48% male), body fat (36.4 ± 7.5 vs. 35.7 ± 7.9%) and AIR [2.3 ± 0.3 vs. 2.3 ± 0.3, pmol/L (log)] as those who did not develop albuminuria but had lower insulin sensitivity [M-low: 0.33 ± 0.08 vs. 0.36 ± 0.12, p = .03; M-high: 0.87 ± 0.11 vs. 0.91 ± 0.12, p = .02; mg/kg-metabolic body size/min (log)]. In separate adjusted models, lower M-low and M-high were both associated with an increased risk for albuminuria [hazard ratio (HR) 1.51, 95% confidence interval (CI) 1.14, 2.00, p = .004; HR 1.31, 95% CI 1.06, 1.63, p = .01), whereas AIR was not (HR 1.15, 95% CI 0.87, 1.56, p = .3). CONCLUSIONS: Lower insulin sensitivity is associated with the development of albuminuria, suggesting a role for insulin signalling in the pathogenesis of proteinuria.

Validation of Total Water Intake from the Automated Self-Administered 24-h Recall, 4-d Food Records, and a Food Frequency Questionnaire Using Doubly Labeled Water.

BACKGROUND: Although prior evidence indicates that water intake is important for health, the ability to accurately measure community-dwelling intake is limited. Only a few studies have evaluated self-reported water intake against an objective recovery biomarker. OBJECTIVES: The aim was to compare preformed water intakes (all sources including food) by multiple Automated Self-Administered 24-h recalls (ASA24s), food frequency questionnaires (FFQs), and 4-d food records (4DFRs) against a recovery biomarker, doubly labeled water (DLW), to assess measurement error. METHODS: Over 1 y, 1082 women and men (50%), aged 50 to 74 y, were asked to complete 6 ASA24s, 2 FFQs, 2 unweighted 4DFRs, and an administration of DLW (n = 686). Geometric means of water intake by self-report tools were compared with DLW. Attenuation factors and correlation coefficients between self-reported and the recovery biomarker (DLW) were estimated. RESULTS: Mean water intakes by DLW were 2777 mL/d (interquartile range, 2350 to 3331) in women and 3243 mL/d (interquartile range, 2720 to 3838) in men. Compared with DLW, water intake was underestimated by 18% to 31% on ASA24s and 43% to 44% on 4DFRs. Estimated geometric means from FFQs differed from DLW by -1% to +13%. For a single ASA24, FFQ, and 4DFR, attenuation factors were 0.28, 0.27, and 0.32 and correlation coefficients were 0.46, 0.48, and 0.49, respectively. Repeated use of 6 ASA24s, 2 FFQs, and 2 4DFRs improved attenuation factors to 0.43, 0.32, and 0.39 and correlation coefficients to 0.58, 0.53, and 0.54, respectively. CONCLUSIONS: FFQs may better estimate population means for usual water intake compared with ASA24 and 4DFR. Similar attenuation factors and correlation coefficients across all self-report tools indicate that researchers have 3 feasible options if the goal is understanding intake-disease relationships. The findings are useful for planning future nutrition studies that set policy priorities for populations and to understand the health impact of water. This trial was registered at clinicaltrials.gov as NCT03268577.

Carbon Isotope Ratios of Plasma and RBC Fatty Acids Identify Meat Consumers in a 12-Week Inpatient Feeding Study of 32 Men.

BACKGROUND: Molecular stable isotope ratios are a novel type of dietary biomarker with high sensitivity and specificity for certain foods. Among these, fatty acid carbon isotope ratios (CIRs) have strong potential but have not been investigated as dietary biomarkers. OBJECTIVES: We evaluated whether fatty acid CIRs and mass proportions were associated with meat, fish, and sugar-sweetened beverage (SSB) intake. METHODS: Thirty-two men [aged 46.2 ± 10.5 y; BMI (kg/m2): 27.2 ± 4.0] underwent a 12-wk inpatient dietary intervention at the National Institute of Diabetes and Digestive and Kidney Diseases in Phoenix, Arizona. Men were randomly assigned to 1 of 8 dietary treatments varying the presence/absence of dietary meat, fish, and SSBs in all combinations. Fatty acid CIRs and mass proportions were measured in fasting blood samples and adipose tissue biopsies that were collected pre- and postintervention. Dietary effects were analyzed using multivariable regression and receiver operating characteristic AUCs were calculated using logistic regression. RESULTS: CIRs of the several abundant SFAs, MUFAs and arachidonic acid (20:4n-6) in plasma were strongly associated with meat, as were a subset of these fatty acids in RBCs. Effect sizes in plasma ranged from 1.01‰ to 1.93‰ and were similar but attenuated in RBCs. Mass proportions of those fatty acids were not associated with diet. CIRs of plasma dihomo-γ-linolenic acid (20:3n-6) and adipose palmitic acid (16:0) were weakly associated with SSBs. Mass proportions of plasma odd-chain fatty acids were associated with meat, and mass proportions of plasma EPA and DHA (20:5n-3 and 22:6n-3) were associated with fish. CONCLUSIONS: CIRs of plasma and RBC fatty acids show promise as sensitive and specific measures of dietary meat. These provide different information from that provided by fatty acid mass proportions, and are informative where mass proportion is not. This trial is registered at www.clinicaltrials.gov as NCT01237093.

Disinhibition augments thirst perception from two dehydrating stimuli in men.

Physiological systems controlling water and energy ingestion are coordinated. Whether maladaptive eating behavior and appetite for water are linked is unknown. Thus, we sought to investigate the association between maladaptive eating and both thirst and water drinking behavior with two dehydrating conditions. Twenty-two lean men and 20 men with obesity (mean age 32.3 ± 8.4 years and 30.0 ± 11.1 years, respectively) completed the Three-Factor Eating Questionnaire (TFEQ) and Gormally Binge Eating Scale. On separate days, volunteers were dehydrated by a 2-h hypertonic saline infusion and a 24-h water deprivation, and thirst was measured on a 100-mm visual analogue scale (VAS) during each procedure. After each dehydrating condition, ad libitum water intake was measured. In the saline infusion, higher Disinhibition on the TFEQ was associated with thirst in the lean group (ß = 4.2 mm VAS, p = 0.03) but not in the group with obesity (p = 0.51). In the water-deprivation condition, higher Disinhibition was also associated with thirst in the lean group (ß = 5.6 mm VAS, p = 0.01) with the strength of relationship being 3.5-fold stronger than that observed in the group with obesity (ß = 1.6 mm VAS, p = 0.0003). Hunger, Restraint, and binge-eating scores were not associated with thirst in either dehydrating condition (all p > 0.05). Maladaptive eating behaviors were not associated with ad libitum water intake (all p > 0.05). Disinhibition is associated with higher thirst perception in healthy weight individuals and may be attenuated in obesity. The characteristics of disinhibition which typically includes a heightened readiness to eat, may reflect a more general phenotype that also reflects a readiness to drink.

Amino Acid Nitrogen Isotope Ratios Respond to Fish and Meat Intake in a 12-Week Inpatient Feeding Study of Men.

BACKGROUND: The natural abundance nitrogen stable isotope ratio (NIR) of whole tissue correlates with animal protein intakes, including meat and fish. Amino acid (AA) NIRs (NIRAAs) are more variable than the whole-tissue NIRs and may thus better differentiate among foods. OBJECTIVES: We evaluated whether NIRAAs were associated with intakes of fish and meat and whether these dietary associations were larger than with whole-tissue NIRs. METHODS: Men were recruited at the National Institute of Diabetes and Digestive and Kidney Diseases in Phoenix, Arizona, and randomly assigned to one of eight 12-wk inpatient dietary interventions, which varied the presence/absence of fish, meat, and sugar-sweetened beverages (SSBs) in all possible combinations. Fasting blood was drawn pre- and postintervention and plasma and RBC NIRAAs (free and protein-bound) were measured as secondary outcomes in 32 participants. Multivariable regression was used to determine responses of postintervention NIRAAs to dietary variables, and logistic regression was used to calculate receiver operating characteristic AUCs. RESULTS: Most plasma NIRAAs increased with fish and meat intakes, but to a greater extent with fish intake. The largest increase in response to fish intake was plasma NIRLeucine (ß = 2.19, SE = 0.26). The NIRThreonine decreased with both fish and meat intakes. Fewer RBC NIRAAs increased with fish intake, and only RBC NIRProline increased with meat intake. No plasma or RBC NIRAA responded to SSB intake. We identified fish intake with a high degree of accuracy using plasma NIRLeucine (corrected AUC, cAUC = 0.96) and NIRGlutamic acid/glutamine (cAUC = 0.93), and meat intake to a lower degree using plasma NIRProline (cAUC = 0.80) and RBC NIRProline (cAUC = 0.85). CONCLUSIONS: Plasma and RBC NIRAAs were associated with fish and meat intakes but were not superior to whole-tissue stable isotope biomarkers in identifying these intakes in a US diet. This trial is registered at www.clinicaltrials.gov as NCT01237093.

Meal-to-meal and day-to-day macronutrient variation in an ad libitum vending food paradigm.

BACKGROUND: Theory posits that macronutrient intake is regulated by protein consumption and adequate intake of protein results in consumption of less carbohydrates and fat. The current study investigates the effect of protein intake on calorie and macronutrient content using an ad libitum vending machine paradigm. METHODS: Healthy volunteers (n = 287; 177 m; Age = 36 ± 11; BMI = 32 ± 8) were admitted to our clinical research unit. Macronutrient meal content (grams) and energy intake (Kcal) were quantified by specialized food processing software and collected on an hourly basis over a three-day period using a validated ad libitum vending machine paradigm. Body composition was assessed by DXA. Lagged multi-level models accounting for age, sex, race/ethnicity, fat and fat free mass indices were fitted to examine the impact of prior macronutrient content on subsequent meals. RESULTS: Protein intake was associated with decreased energy intake (Kcal; B = -1.67 kcal, p = 0.0048), lower protein and carbohydrate intake (B = -0.08 g, p = 0.0006; B = -0.21 g, p = 0.0003, respectively) at subsequent meals. Daily Macronutrient intake and subsequent intake were positively associated. CONCLUSIONS: Dietary protein exhibits a negative regulatory effect on a short-term meal-to-meal rather than day-to-day basis. In the setting of readily available food, protein intake impacts energy intake only over very short time courses.

Lower insulin clearance is associated with increased risk of type 2 diabetes in Native Americans.

AIMS/HYPOTHESIS: Impaired insulin clearance is implicated in the pathogenesis of type 2 diabetes, but prospective evidence remains limited. Therefore, we sought to identify factors associated with the metabolic clearance rate of insulin (MCRI) and to investigate whether lower MCRI is associated with increased risk of incident type 2 diabetes. METHODS: From a longitudinal cohort, 570 adult Native Americans without diabetes living in the Southwestern United States were characterised at baseline and 448 participants were monitored over a median follow-up period of 7.9 years with 146 (32%) incident cases of diabetes identified (fasting plasma glucose ≥7.0 mmol/l, 2 h plasma glucose [2-h PG] ≥11.1 mmol/l, or clinical diagnosis). At baseline, participants underwent dual-energy x-ray absorptiometry or hydrodensitometry to assess body composition, a 75 g OGTT, an IVGTT to assess acute insulin response (AIR), and a hyperinsulinaemic-euglycaemic clamp to assess MCRI and insulin action (M). RESULTS: In adjusted linear models, MCRI was inversely associated with body fat percentage (r = -0.35), fasting plasma insulin (r = -0.55) and AIR (r = -0.22), and positively associated with M (r = 0.17; all p < 0.0001). In multivariable Cox proportional hazard models, lower MCRI was associated with an increased risk of diabetes after adjustment for age, sex, heritage, body fat percentage, AIR, M, fasting plasma glucose, 2-h PG, and fasting plasma insulin (HR per one-SD difference in MCRI: 0.77; 95% CI 0.61, 0.98; p = 0.03). CONCLUSIONS/INTERPRETATION: Lower MCRI is associated with an unfavourable metabolic phenotype and is associated with incident type 2 diabetes independent of established risk factors. CLINICAL TRIAL REGISTRATION NUMBERS: ClinicalTrials.gov NCT00339482; NCT00340132.

Reduced metabolic efficiency in sedentary eucaloric conditions predicts greater weight regain in adults with obesity following sustained weight loss.

BACKGROUND: Successful long-term weight loss maintenance after caloric restriction (CR) is rarely achieved. Besides known metabolic, behavioural, and cognitive factors, 24-hour energy expenditure (24hEE) relative to body size (i.e., metabolic efficiency) might influence subsequent weight loss maintenance. METHODS: Eleven participants with obesity (BMI = 39.0 ± 8.7 kg/m2, body fat = 36.1 ± 6.4%) had 24hEE measured in a whole-room indirect calorimeter during eucaloric conditions and weight stability prior to starting a 6-week inpatient CR study (50% of daily energy needs). Twenty-four-hour energy expenditure was adjusted via regression analysis for fat free mass (FFM) and fat mass (FM) by DXA. Body composition was reassessed at the end of CR and after 1-year follow-up. Free-living weight was assessed by monthly weight measurements during 12 months. RESULTS: After 6-week CR, participants lost 8.5 ± 2.7% weight (FFM: -6.3 ± 3.6 kg, FM: -3.4 ± 1.2 kg) but regained 5.1 ± 8.0% 1 year following CR, which was mostly due to FFM regain (+5.7 ± 5.5 kg) and unchanged FM. A relatively higher 24hEE by 100 kcal/day prior to CR was associated with an average greater rate of weight regain by +0.3 kg/month during follow-up and a greater final weight regain by +5.1 kg after 1 year of follow-up. CONCLUSION: These results suggest that reduced metabolic efficiency in 24hEE during eucaloric, sedentary conditions may predict greater weight regain after CR-induced weight loss.

Cognitive dietary restraint, disinhibition, and hunger are associated with 24-h energy expenditure.

BACKGROUND: Higher energy expenditure (EE) is associated with greater food intake, possibly because the human body senses EE and modifies eating behaviors to regulate food intake and ultimately achieve energy balance. As eating behaviors are also influenced by social and cultural factors, any association between EE and eating behavior may differ between ethnicities and sexes. OBJECTIVE: To assess relationships between EE and eating behavior constructs of the Three-Factor Eating Questionnaire (TFEQ). SUBJECTS/METHODS: In all, 307 healthy adults (201 M/106 F, 160 Native Americans) completed the TFEQ and had measures of 24-h EE in a whole-room calorimeter during energy balance. Body composition was assessed by DXA. RESULTS: On average, adjusted 24-h EE was lower (ß = -229 kcal/day, CI: -309 to -148, p < 0.001) but cognitive restraint (Δ = + 1.5; CI: 0.5 to 2.5, p = 0.003) and disinhibition (Δ = + 2.1, CI: 1.3 to 2.8, p < 0.001) scores were higher in women compared with men. In Native Americans, adjusted 24-h EE (ß = + 94 kcal/day, CI: 48 to 139, p < 0.001) and disinhibition scores (Δ = + 1.0, CI: 0.1 to 2.0, p = 0.003) were higher compared with other ethnicities. Higher 24-h EE associated with lower cognitive restraint in women (ρ = -0.20, p = 0.04), but not men (p = 0.71; interaction term p = 0.01) with no ethnic differences. Greater 24-h EE associated with higher disinhibition (ρ = 0.20, p = 0.001) and hunger cues (ρ = 0.16, p = 0.004) with no gender differences. These associations were primarily present in non-Native Americans (ρ = 0.23, p = 0.006 and ρ = 0.25, p = 0.003) but not observed in Native Americans (both p > 0.40). CONCLUSIONS: Higher EE is associated with psychological constructs of eating behaviors that favors overeating including lower cognitive restraint, higher dietary disinhibition, and greater susceptibility to hungers cues, supporting the existence of energy-sensing mechanisms influencing human eating behavior. These associations were observed in ethnicities other than Native Americans, possibly explaining the contradictory relationships reported between EE and weight change in different ethnic groups. We propose that increased EE may alter eating behaviors, potentially leading to uncontrolled overeating and weight gain.

Response of skeletal muscle UCP2-expression during metabolic adaptation to caloric restriction.

BACKGROUND/OBJECTIVES: Spendthrift vs. thrifty individuals expend more energy and experience greater weight loss during caloric restriction (CR). Adaptive mechanisms in skeletal muscle, adipose tissue, and on hormone level modulate energy expenditure (EE) during weight loss. Metabolic mechanisms underlying the variability in EE during CR are unclear. The present study explored whether during long-term CR (i) gene expression changes in skeletal muscle and adipose tissue relate with the individual EE response and weight loss, and (ii) altered catecholamine and FGF21-concentrations are associated with measures of metabolic adaptation. SUBJECTS/METHODS: In a 10-week inpatient study, 24-h EE was measured before and after 6 weeks of 50% CR in 12 subjects using whole-room indirect calorimetry. Weight loss was assessed and repeated hormone measurements performed. Muscle and adipose tissue biopsies were taken before and after CR, and gene expression was assessed (RNA-Seq). Genes showing the most significant changes after CR were tested for association with EE and followed-up for further association with metabolic measures in a separate phenotyping study (n = 103). RESULTS: Muscle UCP2 showed the strongest change after CR (log2-fold change = -1.57, false discovery rate = 0.10) and was considered the best gene for exploration of metabolic adaptive processes. A greater decrease in UCP2-expression was associated with less weight loss (P = 0.03, r = 0.77) and relatively lower 24-h EE after CR (P = 0.001, r = -0.96). Post-CR changes in FGF21-plasma concentrations correlated with UCP2-expression change (P = 0.02, r = -0.89) and weight loss (P = 0.003, r = -0.83). In a separate metabolic phenotyping study, muscle UCP2-expression correlated with respiratory quotient and macronutrient oxidation. In adipose tissue, no candidate genes for metabolic exploration were found. CONCLUSIONS: Changes in muscle UCP2-expression reflect an inter-individual metabolic response to long-term CR and may influence EE and weight loss via modulation of substrate oxidation.

Decline in the acute insulin response in relationship to plasma glucose concentrations.

BACKGROUND: To investigate (1) whether the decline in acute insulin response (AIR) precedes or coincides with defined glucose regulation categories and whether acute insulin response decline varies by race and adiposity, (2) linearity of the relationship between acute insulin response and increasing plasma glucose concentrations, (3) longitudinal changes in acute insulin response accounting for changes in insulin action across categories of glucose tolerance. METHODS: Clinical cross-sectional and longitudinal study of nondiabetic subjects. Inpatient assessment of oral glucose tolerance (2-h PG, fasting PG), and acute insulin response (intravenous glucose tolerance test) in 326 and 84 Native Americans of full and ≤6/8th Southwestern heritage, respectively, and 115 Whites. Linearity of acute insulin response vs plasma glucose concentrations investigated using spline analyses. Follow-up (average = 2.07 years) glucose tolerance, acute insulin response, and insulin action (hyperinsulinemic-euglycemic clamp) assessed in 230 full Native Americans. RESULTS: In certain groups, the relationship between acute insulin response and increasing plasma glucose levels was non-linear. In all groups, acute insulin response decline preceded the cut-offs for traditional glucose regulation categories, although the timing with respect to increasing plasma glucose varied by race and adiposity. Longitudinal data indicated that improvement in insulin action is the key factor to preserve insulin secretion, underlying the reversion of glucose tolerance in prediabetic individuals. CONCLUSIONS: With worsening insulin action, the decline in insulin secretion occurred prior to current diagnostic guidelines for impaired glucose regulation. However, the relationship between acute insulin response and increasing plasma glucose varies and was not always non-linear. Understanding the dynamics of this relationship may determine when to initiate preventive pharmacotherapy directed at the preservation of ß-cell failure.

One-hour and two-hour postload plasma glucose concentrations are comparable predictors of type 2 diabetes mellitus in Southwestern Native Americans.

AIMS/HYPOTHESIS: Elevated 2-h plasma glucose concentration (2 h-PG) during a 75 g OGTT predict the development of type 2 diabetes mellitus. However, 1-h plasma glucose concentration (1 h-PG) is associated with insulin secretion and may be a better predictor of type 2 diabetes. We aimed to investigate the association between 1 h-PG and 2 h-PG using gold standard methods for measuring insulin secretion and action. We also compared 1 h-PG and 2 h-PG as predictors of type 2 diabetes mellitus. METHODS: This analysis included adult volunteers without diabetes, predominantly Native Americans of Southwestern heritage, who were involved in a longitudinal epidemiological study from 1965 to 2007, with a baseline OGTT that included measurement of 1 h-PG. Group 1 (n = 716) underwent an IVGTT and hyperinsulinaemic-euglycaemic clamp for measurement of acute insulin response (AIR) and insulin-stimulated glucose disposal (M), respectively. Some members of Group 1 (n = 490 of 716) and members of a second, larger, group (Group 2; n = 1946) were followed-up to assess the development of type 2 diabetes (median 9.0 and 12.8 years follow-up, respectively). RESULTS: Compared with 2 h-PG (r = -0.281), 1 h-PG (r = -0.384) was more closely associated with AIR, whereas, compared with 1 h-PG (r = -0.340), 2 h-PG (r = -0.408) was more closely associated with M. Measures of 1 h-PG and 2 h-PG had similar abilities to predict type 2 diabetes, which did not change when both were included in the model. A 1 h-PG cut-off of 9.3 mmol/l provided similar levels of sensitivity and specificity as a 2 h-PG cut-off of 7.8 mmol/l; the latter is used to define impaired glucose tolerance, a recognised predictor of type 2 diabetes mellitus. CONCLUSIONS/INTERPRETATION: The 1 h-PG was associated with important physiological predictors of type 2 diabetes and was as effective as 2 h-PG for predicting type 2 diabetes mellitus. The 1 h-PG is, therefore, an alternative method of identifying individuals with an elevated risk of type 2 diabetes mellitus.

Autoantibodies against PFDN2 are associated with an increased risk of type 2 diabetes: A case-control study.

BACKGROUND: The adaptive immune system is involved in type 2 diabetes mellitus (T2DM), indicating the presence of unidentified autoantibodies that might be useful biomarkers for emerging immunomodulatory therapy. A prior microarray study with a small number of participants suggested the association of novel autoantibodies with T2DM in Southwest American Indians. We therefore sought to determine whether antibodies against 14 target proteins are associated with T2DM in a large case-control study. METHODS: Participants were adults (age 20-59 y) of Southwest American Indian heritage. Plasma antibodies against 14 possible target proteins were measured in 476 cases with T2DM of less than 5 years duration and compared with 424 controls with normal glucose regulation. RESULTS: Higher levels of antibodies against prefoldin subunit 2 (PFDN2) were associated with T2DM (P = .0001; Bonferroni-corrected threshold for multiple tests = 0.0036 [α = 0.05]). The association between anti-PFDN2 antibodies and T2DM remained in multivariable logistic regression (odds ratio 1.27; 95% confidence interval, 1.09-1.49; per one SD difference in anti-PFDN2 antibody). The odds of T2DM were increased in the highest anti-PFDN2 antibody quintile by 66% compared with the lowest quintile. Differences in anti-PFDN2 antibodies were most prominent among cases with earlier onset of disease (ie, age 20-39 y) compared with controls. CONCLUSIONS: Anti-PFDN2 antibodies are associated with T2DM and might be a useful biomarker. These findings indicate that autoimmunity may play a role in T2DM in Southwest American Indians, especially among adults presenting with young onset of disease.

T-cell receptor repertoire variation may be associated with type 2 diabetes mellitus in humans.

BACKGROUND: Recent work in Pima Indians, a population with high rates of obesity and type 2 diabetes mellitus (T2DM), demonstrated that human leukocyte antigen haplotype DRB1*02 carriers have an increased acute insulin response and decreased risk for the development of T2DM, implicating loss of self-tolerance in the pathogenesis of T2DM. Advances in genomic sequencing have made T-cell receptor repertoire analysis a practical mode of investigation. METHODS: High-throughput sequencing of T-cell receptor complementarity-determining region 3 was carried out in male Pima Indians with normal glucose regulation (n = 11; age = 31 ± 8 years; %fat = 30.2 ± 8.7%) and the protective DRB1*02 haplotype versus those with T2DM without DRB1*02 (n = 7; age = 34 ± 8 years; %fat = 31.2 ± 4.7%). Findings were partially replicated in another cohort by assessing the predictive ability of T-cell receptor variation on risk of T2DM in Pima Indian men (n = 27; age = 28.9 ± 7.1 years; %fat = 28.8 ± 7.1%) and women (n = 20; age = 29 ± 7.0 years; %fat = 37.1 ± 6.8%) with baseline normal glucose regulation but without the protective haplotype who were invited to follow-up examinations as frequently as every 2 years where diabetes status was assessed by a 75-g oral glucose tolerance test. Of these subjects, 13 developed diabetes. RESULTS: T-cell receptor complementarity-determining region 3 length was shorter in those with T2DM, and a one-nucleotide decrease in complementarity-determining region 3 length was associated with a nearly threefold increase in risk for future diabetes. The frequency of one variable gene, TRBV7-8, was higher in those with T2DM. A 1% increase in TRBV7-8 frequency was associated with a greater than threefold increase in diabetes risk. CONCLUSIONS: These results indicate that T-cell autoimmunity may be an important component in progression to T2DM in Pima Indians.

A potential role for the midbrain in integrating fat-free mass determined energy needs: An H2 (15) O PET study.

Little is known on how sensing of energy needs is centrally represented, integrated, and translated into the behavioral aspects of energy homeostasis. Fat free mass (FFM) is the major determinant of energy expenditure. We investigated how interindividual variances in FFM relate to neuronal activity in humans. Healthy adults (n = 64, 21F/43M; age 31.3 ± 9.1y; percentage of body fat [PFAT] 25.6 ± 10.7%; BMI 30.4 ± 9) underwent a 36h fast and subsequent H(2) (15) O positron emission tomographic (PET) measurement of regional cerebral blood flow (rCBF). Multiple variable regression analysis revealed significant associations of FFM with rCBF within the midbrain [including parts of the periaqueductal gray (PAG), ventral tegmental area (VTA), thalamic and hypothalamic regions], the bilateral parahippocampal region, left anterior cingulate, left insular cortex, right cerebellum, and distinct regions within the temporal and occipital cortex. In contrast, no significant associations were found for fat mass (FM). We investigated the potential functional-anatomical link between FFM and central regulation of food intake by performing a conjunction analysis of FFM and the perceived hunger feelings. This showed a significant overlap within the midbrain PAG. Mediation analysis demonstrated a significant indirect effect of FFM on hunger with PAG rCBF as mediator. Most regions we found to be associated with FFM form part in ascending homeostatic pathways and cortical circuitries implicated in the regulation of basic bodily functions indicating a potential role of these central networks in the integration of FFM determined energy needs.

Increased 24-hour ad libitum food intake is associated with lower plasma irisin concentrations the following morning in adult humans.

BACKGROUND: The relationship between food intake and irisin concentrations in humans is unclear. OBJECTIVES: To determine whether the previous day's intake impacts fasting plasma irisin concentrations, or whether fasting irisin concentrations associate with subsequent ad libitum food intake. METHODS: Sixty-six nondiabetic adults (42 men) were admitted for a study of the determinants of energy intake. After 6 days of a weight maintaining diet, ad libitum energy intake over 3 days was assessed using a vending machine paradigm. Fasting plasma irisin concentrations were measured on the morning of the second day of the vending period. RESULTS: There were no correlations between irisin and demographic or anthropometric parameters. On day 1, subjects consumed 144 ± 52% of weight maintaining energy needs. Every additional 500 kcal consumed on day 1 associated with a 3.4% lower irisin concentration the following morning (95% CI -6.2, -0.4%, p = 0.01; adjusted for age, sex and race). If energy intake was expressed as a percentage of weight maintaining energy needs, every 10% increase associated with a 1.9% lower irisin concentration (95% CI -3.7, -0.1%; adjusted p = 0.02). A 100 kcal increase in carbohydrate or fat consumption associated with a 1.3% (95% CI -2.5, -0.1%, p = 0.01) and a 0.6% (95% CI -1.1, -0.0%, p = 0.02) lower irisin concentration, respectively. There was no association between fasting irisin concentrations and subsequent energy intake on day 2 (r = 0.19, p = 0.1). CONCLUSIONS: Higher ad libitum 24 h energy intake was associated with lower fasting irisin concentrations the following morning, but fasting irisin concentrations did not predict subsequent energy intake. The decrease in irisin concentrations with increased energy intake is consistent with the detrimental metabolic effects of overeating.

Perseveration augments the effects of cognitive restraint on ad libitum food intake in adults seeking weight loss.

As executive function may influence eating behaviors, our aim was to determine whether measures of executive function predict ad libitum food intake in subjects seeking weight loss. 78 obese, healthy individuals (40 female/38 male; age 36 ± 10 y; BMI 37.8 ± 7.2 kg/m(2)) completed the Iowa Gambling Task to evaluate decision making, the Stroop Word Color Task to assess attention, the Wisconsin Card Sorting Task to measure perseveration, and the Three Factor Eating Questionnaire to measure disinhibition and cognitive restraint. Ad libitum energy intake over 3-days was then collected using a validated vending paradigm. When expressed as a percentage of an individual's weight maintaining energy needs (%WMEN), intake correlated positively with perseveration (r=0.24, p=0.03) and negatively with restraint (r=-0.51, p<0.0001). In a regression model of %WMEN (r(2)=0.59, p<0.0001), an interaction between perseveration and restraint was observed (p=0.05). Increased perseveration intensified the effect of restraint such that subjects with both high restraint and perseveration ate the least (median (IQR)=70 (62, 94) %WMEN), while those with low restraint and high perseveration ate the most (130 (102, 153) %WMEN). Subjects with low perseveration and high versus low restraint ate a median of 84 (70, 86) and 112 (98, 133) %WMEN, respectively. The effects of perseveration on food intake are conditional on restraint, and may contribute to extremes of dietary intake in some individuals.

Twenty-Four-Hour Urinary Sugars Biomarker in a Vending Machine Intake Paradigm in a Diverse Population.

Accurately measuring dietary sugars intake in large-scale epidemiological studies is necessary to understand dietary sugars' true impact on health. Researchers have developed a biomarker that can be used to assess total sugars intake. Our objective is to test this biomarker in diverse populations using an ad libitum intake protocol. Healthy adult participants (n = 63; 58% Indigenous Americans/Alaska Natives; 60% male; BMI (mean ± SD) = 30.6 ± 7.6 kg.m2) were admitted for a 10-day inpatient stay. On day 2, body composition was measured by DXA, and over the last 3 days, ad libitum dietary intake was measured using a validated vending machine paradigm. Over the same days, participants collected daily 24 h urine used to measure sucrose and fructose. The 24 h urinary sucrose and fructose biomarker (24hruSF) (mg/d) represents the sum of 24 h urinary sucrose and fructose excretion levels. The association between the 3-day mean total sugars intake and log 24uSF level was assessed using the Pearson correlation. A linear mixed model regressing log-biomarker on total sugars intake was used to investigate further the association between biomarker, diet, and other covariates. Mean (S.D.) total sugars intake for the group was 197.7 g/d (78.9). Log 24uSF biomarker was moderately correlated with total sugars intake (r = 0.33, p = 0.01). In stratified analyses, the correlation was strongest in females (r = 0.45, p = 0.028), the 18-30 age group (r = 0.44, p = 0.079), Indigenous Americans (r = 0.51, p = 0.0023), and the normal BMI category (r = 0.66, p = 0.027). The model adjusted for sex, age, body fat percent, and race/ethnicity demonstrated a statistically significant association between 24uSF and total sugars intake (ß = 0.0027, p < 0.0001) and explained 31% of 24uSF variance (marginal R2 = 0.31). Our results demonstrated a significant relationship between total sugars intake and the 24uSF biomarker in this diverse population. However, the results were not as strong as those of controlled feeding studies that investigated this biomarker.

Secular trends and determinants of ad libitum energy intake measured in a research setting from 1999-2020.

Introduction: Historically, secular and seasonal trend analyses have been examined using self-report measures of intake. Rarely are objective measures and known determinants of dietary intake used in these analyses. Our objective was to quantify the seasonal and secular differences in an objective ad libitum intake paradigm while considering the contribution of determinants, such as fat-free mass (FFM) index and spontaneous physical activity (SPA) limited to the restricted space of a whole-room calorimeter. Methods: For this study, recruitment of N = 292 healthy, diabetes free, adults occurred from 1999 to 2020. Assessment during their 10-day stay included body composition (by DXA), SPA (by an approximately 24-h stay in whole-room calorimetry), and ad libitum intake (by a vending machine for 3 days). This secondary analysis used general linear models (GLM) to investigate secular and seasonal differences while adjusting for sex, age, FFM index, FM (fat mass) index, SPA, and race/ethnicity. Results: FFM index and SPA were positively associated with all intake measures (p < 0.05). In all adjusted seasonal models, season did not affect intake. Adjusted secular trends models (kcals/year) demonstrated a decrease in total kcals (ß = -55), intake as percent weight maintaining energy needs (ß = -2), protein kcals (ß = -10), fat kcals (ß = -27), and carbohydrates kcals (ß = -22) (all p < 0.05). After further adjustment for SPA, significance remained in all intake measures (p < 0.05). Secular trends in body composition revealed no changes in weight, BMI, and percent body fat (all p > 0.20). Discussion: Our results indicate that over time, ad libitum intake decreased in this controlled research setting and remained significant even after accounting for positive determinants of intake. A significant ad libitum decrease, coupled with no change in body composition, may highlight a participant bias toward calorie restriction in a controlled setting over time and deserves further investigation.