Glucose response to an oral glucose tolerance test predicts weight change in non-diabetic subjects

Impact of Hunger, Satiety, and Oral Glucose on the Association Between Insulin and Resting-State Human Brain Activity

To study the interplay of metabolic state (hungry vs. satiated) and glucose administration (including hormonal modulation) on brain function, resting-state functional magnetic resonance imaging (rs-fMRI) and blood samples were obtained in 24 healthy normal-weight men in a repeated measurement design. Participants were measured twice: once after a 36 h fast (except water) and once under satiation (three meals/day for 36 h). During each session, rs-fMRI and hormone concentrations were recorded before and after a 75 g oral dose of glucose. We calculated the amplitude map from blood-oxygen-level-dependent (BOLD) signals by using the fractional amplitude of low-frequency fluctuation (fALFF) approach for each volunteer per condition. Using multiple linear regression analysis (MLRA) the interdependence of brain activity, plasma insulin and blood glucose was investigated. We observed a modulatory impact of fasting state on intrinsic brain activity in the posterior cingulate cortex (PCC). Strikingly, differences in plasma insulin levels between hunger and satiety states after glucose administration at the time of the scan were negatively related to brain activity in the posterior insula and superior frontal gyrus (SFG), while plasma glucose levels were positively associated with activity changes in the fusiform gyrus. Furthermore, we could show that changes in plasma insulin enhanced the connectivity between the posterior insula and SFG. Our results indicate that hormonal signals like insulin alleviate an acute hemostatic energy deficit by modifying the homeostatic and frontal circuitry of the human brain.

Effects of Eight Weeks of High Intensity Functional Training on Glucose Control and Body Composition among Overweight and Obese Adults

High-intensity exercise has been found to positively influence glucose control, however, the effects of high-intensity functional training (HIFT) for overweight and obese sedentary adults without diabetes is unknown. The purpose of this study was to examine changes in body composition and glucose control from eight weeks of aerobic and resistance training (A-RT) compared to HIFT. Session time spent doing daily workouts was recorded for each group. Baseline and posttest measures included height, weight, waist circumference, dual X-ray absorptiometry (body fat percentage, fat mass, lean mass), and fasting blood glucose. Participants completing the intervention (78%, n = 9 per group) were 67% female, age = 26.8 ± 5.5 years, and had body mass index = 30.5 ± 2.9 kg/m². Fasting blood glucose and 2-h oral glucose tolerance tests were used as primary outcome variables. On average, the HIFT group spent significantly less time completing workouts per day and week (ps < 0.001). No significant differences were found for body composition or glucose variables within- or between-groups. Even though our findings did not provide significant differences between groups, future research may utilize the effect sizes from our study to conduct fully-powered trials comparing HIFT with other more traditional training modalities.

Safety and efficacy of pasireotide in dumping syndrome-results from a phase 2, multicentre study

BACKGROUND

Dumping syndrome is a prevalent complication of oesophageal and gastric surgery characterised by early (postprandial tachycardia) and late (hypoglycaemia) postprandial symptoms.

AIM

To evaluate efficacy and safety of the somatostatin analogue, pasireotide in patients with dumping syndrome after bariatric or upper gastrointestinal cancer surgery.

METHODS

A single-arm, open-label, multicentre, intrapatient dose-escalation, phase 2 study with 4 phases: screening, 3-month SC (subcutaneous), 3-month IM (intramuscular) and 6-month optional extension IM phase. Primary endpoint was the proportion of patients without hypoglycaemia (plasma glucose <3.3 mmol/L [60 mg/dL] during an oral glucose tolerance test, OGTT) at the end of 3-month SC phase. A ≥50% response rate was considered clinically relevant.

RESULTS

Forty-three patients with late dumping were enrolled; 33 completed the 3-month SC phase and 23 completed the 12-month study. The proportion of patients without hypoglycaemia at month 3 (primary endpoint) was 60.5% (26 of 43; 95% confidence interval, 44.4%-75.0%). Improvement in quality of life was observed during SC phase, which was maintained in the IM phase. The proportion of patients with a rise in pulse rate of ≥10 beats/min during OGTT reduced from baseline (60.5%) to month 3 (18.6%) and month 12 (27.3%). Overall (month 0-12), the most frequent (>20% of patients) adverse events were headache (34.9%); diarrhoea, hypoglycaemia (27.9% each); fatigue, nausea (23.3% each); and abdominal pain (20.9%).

CONCLUSION

These results suggest that pasireotide is a promising option in patients with dumping syndrome after bariatric or upper gastrointestinal cancer surgery.

Influences of Hunger, Satiety and Oral Glucose on Functional Brain Connectivity: A Multimethod Resting-State fMRI Study

A major regulatory task of the organism is to keep brain functions relatively constant in spite of metabolic changes (e.g., hunger vs. satiety) or availability of energy (e.g., glucose administration). Resting-state functional magnetic resonance imaging (rs-fMRI) can reveal resulting changes in brain function but previous studies have focused mostly on the hypothalamus. Therefore, we took a whole-brain approach and examined 24 healthy normal-weight men once after 36 h of fasting and once in a satiated state (six meals over the course of 36 h). At the end of each treatment, rs-fMRI was recorded before and after the oral administration of 75 g of glucose. We calculated local connectivity (regional homogeneity [ReHo]), global connectivity (degree of centrality [DC]), and amplitude (fractional amplitude of low-frequency fluctuation [fALFF]) maps from the rs-fMRI data. We found that glucose administration reduced all measures selectively in the left supplementary motor area and increased ReHo and fALFF in the right middle and superior frontal gyri. For fALFF, we observed a significant interaction between metabolic states and glucose in the left thalamus. This interaction was driven by a fALFF increase after glucose treatment in the hunger relative to the satiety condition. Our results indicate that fALFF analysis is the most sensitive measure to detect effects of metabolic states on resting-state brain activity. Moreover, we show that multimethod rs-fMRI provides an unbiased approach to identify spontaneous brain activity associated with changes in homeostasis and caloric intake.

Fasting hyperglycemia predicts lower rates of weight gain by increased energy expenditure and fat oxidation rate

CONTEXT

Increased adiposity and insulin resistance are associated with hyperglycemia and previous studies have reported that higher glucoses are associated with lower rates of weight gain. One possible mechanism is via increased energy expenditure (EE).

OBJECTIVE

To assess the relationships between changes in EE during spontaneous weight gain and concomitant changes in glucose levels.

DESIGN AND PARTICIPANTS

Body composition, metabolic, and glycemic data were available from nondiabetic Native Americans who underwent two measurements of 24-h EE during eucaloric feeding in a metabolic chamber (N = 144; time between measurements: 5.0 ± 3.3 years) or resting EE by ventilated hood system during the euglycemic-hyperinsulinemic clamp (N = 261; 4.5 ± 3.2 years). Long-term follow-up data (8.3 ± 4.3 years) for weight and body composition were available in 131 and 122 subjects, respectively.

MAIN OUTCOME MEASURES

Twenty four hour EE and respiratory quotient (RQ), resting (RMR), and sleeping (SMR) metabolic rates, glucose, and insulin levels, basal glucose output (BGO).

RESULTS

Weight gain-associated increase in fasting plasma glucose (FPG) levels was accompanied with decreased 24-h RQ (partial R = -0.24, P = .002) and increased 24-h EE, RMR, SMR, and fat oxidation after accounting for changes in body composition (partial R: 0.12 to 0.19, all P ≤ .05). Upon weight gain, BGO tended to increase (P = .07), while insulin infusion induced a decrease in EE (P = .04). Higher baseline FPG predicted lower rates of future weight gain (partial R = -0.18, P = .04).

CONCLUSIONS

Higher FPG after weight gain was associated with greater-than-expected increase in EE. The rise in BGO and the insulin-induced EE suppression at follow-up indicate that increased hepatic gluconeogenesis may be an important mediator of EE changes associated with weight gain.

Caloric restriction induces changes in insulin and body weight measurements that are inversely associated with subsequent weight regain

BACKGROUND

Successful weight maintenance following weight loss is challenging for many people. Identifying predictors of longer-term success will help target clinical resources more effectively. To date, focus has been predominantly on the identification of predictors of weight loss. The goal of the current study was to determine if changes in anthropometric and clinical parameters during acute weight loss are associated with subsequent weight regain.

METHODOLOGY

The study consisted of an 8-week low calorie diet (LCD) followed by a 6-month weight maintenance phase. Anthropometric and clinical parameters were analyzed before and after the LCD in the 285 participants (112 men, 173 women) who regained weight during the weight maintenance phase. Mixed model ANOVA, Spearman correlation, and linear regression were used to study the relationships between clinical measurements and weight regain.

PRINCIPAL FINDINGS

Gender differences were observed for body weight and several clinical parameters at both baseline and during the LCD-induced weight loss phase. LCD-induced changes in BMI (Spearman's ρ = 0.22, p = 0.0002) were inversely associated with weight regain in both men and women. LCD-induced changes in fasting insulin (ρ = 0.18, p = 0.0043) and HOMA-IR (ρ = 0.19, p = 0.0023) were also associated independently with weight regain in both genders. The aforementioned associations remained statistically significant in regression models taking account of variables known to independently influence body weight.

CONCLUSIONS/SIGNIFICANCE

LCD-induced changes in BMI, fasting insulin, and HOMA-IR are inversely associated with weight regain in the 6-month period following weight loss.

(Still) longing for food: insulin reactivity modulates response to food pictures

Overweight and obesity pose serious challenges to public health and are promoted by our food-rich environment. We used functional magnetic resonance imaging (fMRI) to investigate reactivity to food cues after overnight fasting and following a standardized caloric intake (i.e., a 75 g oral glucose tolerance test, OGTT) in 26 participants (body mass index, BMI between 18.5 and 24.9 kg m(-2)). They viewed pictures of palatable food and low-level control stimuli in a block design and rated their current appetite after each block. Compared to control pictures, food pictures activated a large bilateral network typically involved in homeostatically and hedonically motivated food processing. Glucose ingestion was followed by decreased activation in the basal ganglia and paralimbic regions and increased activation in parietal and occipital regions. Plasma level increases in insulin correlated with cue-induced appetite at the neural and behavioral level. High insulin increases were associated with reduced activation in various bilateral regions including the fusiform gyrus, the superior temporal gyrus, the medial frontal gyrus, and the limbic system in the right hemisphere. In addition, they were accompanied by lower subjective appetite ratings following food pictures and modulated the neural response associated with it (e.g., in the fusiform gyrus). We conclude that individual insulin reactivity is critical to reduce food-cue responsivity after an initial energy intake and thereby may help to counteract overeating.

Body weight, not insulin sensitivity or secretion, may predict spontaneous weight changes in nondiabetic and prediabetic subjects: the RISC study

OBJECTIVE

Previous studies have found that high insulin sensitivity predicts weight gain; this association has not been confirmed. Our aim was to systematically analyze metabolic predictors of spontaneous weight changes.

RESEARCH DESIGN AND METHODS

In 561 women and 467 men from the Relationship Between Insulin Sensitivity and Cardiovascular Disease (RISC) cohort (mean age 44 years, BMI range 19-44 kg/m(2), 9% impaired glucose tolerance) followed up for 3 years, we measured insulin sensitivity (by a euglycemic clamp) and β-cell function (by modeling of the C-peptide response to oral glucose and by acute insulin response to intravenous glucose).

RESULTS

Insulin sensitivity was similar in weight gainers (top 20% of the distribution of BMI changes), weight losers (bottom 20%), and weight stable subjects across quartiles of baseline BMI. By multiple logistic or linear regression analyses controlling for center, age, sex, and baseline BMI, neither insulin sensitivity nor any β-cell function parameter showed an independent association with weight gain; this was true in normal glucose tolerance, impaired glucose tolerance, and whether subjects progressed to dysglycemia or not. Baseline BMI was significantly higher in gainers (26.1 ± 4.1 kg/m(2)) and losers (26.6 ± 3.7 kg/m(2)) than in weight stable subjects (24.8 ± 3.8 kg/m(2), P<0.0001 for both gainers and losers). Baseline waist circumference (or equivalently, BMI or weight) was a positive, independent predictor of both weight gain and weight loss (odds ratio 1.48 [95% CI 1.12-1.97]) in men and (1.67 [1.28-2.12]) in women. In men only, better insulin sensitivity was an additional independent predictor of weight loss.

CONCLUSIONS

Neither insulin sensitivity nor insulin secretion predicts spontaneous weight gain. Individuals who have attained a higher weight are prone to either gaining or losing weight regardless of their glucose tolerance.

Glucose metabolism and diet predict changes in adiposity and fat distribution in weight-reduced women

Among obesity-prone individuals, metabolic state may interact with diet in determining body composition. We tested the hypotheses that, among 103 weight-reduced women over 1 year, (i) insulin sensitivity would be positively associated with change in %fat; (ii) this association would be modulated by dietary glycemic load (GL); and (iii) changes in fat distribution would be related to indexes of glucose metabolism. Insulin sensitivity, glucose effectiveness, fasting and postchallenge insulin and glucose, and glucose tolerance were assessed during intravenous glucose tolerance test (IVGTT). Changes in %fat and fat distribution were examined using dual-energy X-ray absorptiometry and computed tomography. Dietary GL was assessed on 67 women using food records. On average, women showed a +5.3 +/- 3.0% change in %fat over 1 year, with the magnitude of this change being greater in relatively insulin sensitive women (+6.0 +/- 0.4%, mean +/- s.e.m.) than in relatively insulin resistant women (+4.4 +/- 0.4 kg; P < 0.05). Women who were relatively insulin sensitive and who consumed a higher GL diet showed a +6.8 +/- 0.7% change in %fat, which was greater than those who were less insulin sensitive, regardless of diet (P < 0.05), but did not differ from women who were relatively insulin sensitive and who consumed a lower GL diet (P = 0.105). Changes in intra-abdominal and deep subcutaneous abdominal fat were inversely associated with the postchallenge decline in serum glucose. In conclusion, greater insulin sensitivity may predispose to adiposity among weight reduced women, an effect that may be ameliorated by a lower GL diet. The potential association between indexes of glucose disposal and changes in fat distribution warrants further study.

Prospective investigation of metabolic characteristics in relation to weight gain in older adults: the Hoorn Study

The objective of this investigation was to determine the relation between baseline glucose, insulin, adiponectin, and leptin levels and subsequent 6-year weight and waist change in older men and women without diabetes in a prospective cohort study. Participants were 1,198 Dutch men and women without diabetes who were aged 50-77 years when baseline metabolic and anthropometric measurements were evaluated (1989-1991). Approximately 6 years later, body weight and waist circumference were re-measured at a follow-up examination (1996-1998). Metabolic variables (fasting plasma glucose, 2-h postchallenge plasma glucose, homeostasis model assessment of insulin resistance (HOMA-IR), adiponectin, and leptin) were evaluated as predictors of changes in weight and waist circumference. Postchallenge plasma glucose (mmol/l) significantly predicted less gain in both weight and waist circumference (beta = -0.28 kg, s.e. = 0.11; beta = -0.31 cm, s.e. = 0.14, respectively) during follow-up. Leptin (microg/l) significantly predicted greater increases in weight (beta = 0.29 kg, s.e. = 0.07) and waist (beta = 0.16 cm, s.e. = 0.08) among men and in waist among women (beta = 0.06 cm, s.e. = 0.02). Fasting plasma glucose (mmol/l) predicted an increase in waist among women (beta = 1.59 cm, s.e. = 0.63), but not in men (beta = -0.74 cm, s.e. = 0.55). Adiponectin and insulin did not predict weight or waist change. The authors conclude that lower postchallenge plasma glucose and higher fasting leptin levels significantly predicted long-term increases in weight and waist circumference. In contrast, measures of insulin resistance and adiponectin were not associated with weight change in this cohort of older persons without diabetes.

Alcohol drinking frequency in relation to subsequent changes in waist circumference

BACKGROUND

Cross-sectional studies have reported a lower prevalence of abdominal obese persons among frequent drinkers than among nonfrequent drinkers.

OBJECTIVE

We tested the hypothesis that drinking frequency is associated with subsequent changes in waist circumference.

DESIGN

Data come from a prospective cohort study conducted in 1993-1997 (baseline) and 1999-2002 (follow-up) and included 43 543 men and women. Baseline information on alcohol drinking frequency was related to 1) change in waist circumference by linear regression and 2) major gain and major loss in waist circumference (defined as waist change in the lowest or highest quintile of waist changes) by polytomous logistic regression, also taking into account amount of alcohol intake.

RESULTS

Drinking frequency was inversely associated with changes in waist circumference in women and was unassociated with changes in waist circumference in men. Drinking frequency was unassociated with major waist loss but was inversely associated with major waist gain: odds ratios among men were 0.97 (95% CI: 0.73, 1.28), 0.95 (95% CI: 0.81, 1.12), 0.88 (95% CI: 0.77, 0.99), 0.82 (95% CI: 0.71, -0.95), and 0.79 (95% CI: 0.69, 0.9) for never drinking, drinking on 1, 2-4, 5-6, and 7 d/wk, respectively, compared with men who drank alcohol on <1 d/wk (P for trend < 0.0001). Results for women were similar. Adjustment for the amount of alcohol intake or total energy intake did not affect results considerably.

CONCLUSIONS

Drinking pattern may be associated with development of abdominal obesity; in this prospective study, drinking frequency was inversely associated with major waist gain and was unassociated with major waist loss.

The 24-h carbohydrate oxidation rate in a human respiratory chamber predicts ad libitum food intake

BACKGROUND

The 24-h respiratory quotient (24-h RQ) and 24-h carbohydrate balance (24-h CHO-Bal) are predictors of weight change. Whether these relations are mediated by the effects of substrate oxidation and balance on food intake is not known.

OBJECTIVE

We tested whether substrate oxidation and balance predict future ad libitum food intake.

DESIGN

Substrate oxidation and balance were measured in a respiratory chamber in 112 normoglycemic subjects (83 Pima Indians and 29 whites; 67 men and 45 women) in energy balance for 3 d before tests were performed. The subjects then self-selected their food ad libitum for the following 3 d.

RESULTS

The 24-h RQ, 24-h carbohydrate oxidation (24-h CHO-Ox), and 24-h CHO-Bal in the respiratory chamber predicted subsequent ad libitum food intake over 3 d (as a percentage of weight maintenance energy needs; %EN-WM). The 24-h CHO-Ox explained 15% of the variance in %EN-WM. The weight change over the 3-d ad libitum period was associated positively with 24-h CHO-Ox and negatively with 24-h CHO-Bal in the chamber; these associations were no longer significant after adjustment for %EN-WM.

CONCLUSION

Carbohydrate oxidation and balance predict subsequent ad libitum food intake and can influence short-term weight changes, which indicates that carbohydrate balance is a contributing metabolic factor affecting food intake.