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Various metabolic processes in the body oscillate throughout the natural day, driven by a biological clock. Circadian rhythms are also influenced by time cues from the environment (light exposure) and behaviour (eating and exercise). Recent evidence from diurnal- and circadian-rhythm studies indicates rhythmicity in various circulating metabolites, insulin secretion and -sensitivity and energy expenditure in metabolically healthy adults. These rhythms have been shown to be disturbed in adults with obesity-related metabolic disturbances. Moreover, eating and being (in)active at a time that the body is not prepared for it, as in night-shift work, is related to poor metabolic outcomes. These findings indicate the relevance of 24-h metabolism in obesity-related metabolic alterations and have also led to novel strategies, such as timing of food intake and exercise, to reinforce the circadian rhythm and thereby improving metabolic health. This review aims to deepen the understanding of the influence of the circadian system on metabolic processes and obesity-related metabolic disturbances and to discuss novel time-based strategies that may be helpful in combating metabolic disease.

Background Obesity and insulin dysregulation (ID) predispose horses to laminitis. Determination of management practices or phenotypic markers associated with ID may benefit animal welfare. Objectives Determine ID status of a population of Finnhorses using an oral sugar test (OST) and compare phenotypes and management factors between ID and non-ID Finnhorses. Animals One hundred twenty-eight purebred Finnhorses >= 3 years of age. Methods Owners were recruited using an online questionnaire regarding signalment, history, feeding, and exercise of their horses. Selected contributing stables within a predefined area were visited. Phenotypic markers of obesity and the weight of each horse were recorded. After fasting overnight, horses received 0.45 mL/kg corn syrup PO. Serum samples before and at 60 and 90 minutes after syrup administration were analyzed for insulin by chemiluminescent assay. Horses met ID criteria if insulin concentrations were >= 33 mu IU/mL at T0, >= 66 mu IU/mL at T60 or T90 or some combination thereof. Associations between phenotypic markers, feeding and exercise variables, and ID were examined using mixed effects logistic regression modeling. Results Several phenotypic markers of obesity were significant on univariable analysis but in the final multivariable model, only obesity (body condition score >= 8) was associated with ID (P= .04). Over half of the horses (60% [95% confidence interval (CI), 51%-68%]) were considered overweight or obese whereas 16% (95% CI, 10%-23%) were classified as having ID. Conclusions and Clinical Importance Because obesity is associated with ID in cold-blooded type horses, objective monitoring of phenotypic markers by owners may be beneficial for health outcomes.

Aims Given the benefits of sodium glucose co-transporter 2 inhibition (SGLT2i) in protecting against heart failure in diabetic patients, we sought to explore the potential impact of SGLT2i on the clinical features of patients presenting with myocardial infarction (MI) through a post hoc analysis of CANVAS Programme and CREDENCE trial. Methods and results Individuals with type 2 diabetes and history or high risk of cardiovascular disease (CANVAS Programme) or type 2 diabetes and chronic kidney disease (CREDENCE) were included. The intervention was canagliflozin 100 or 300 mg (combined in the analysis) or placebo. MI events were adjudicated as ST-elevation myocardial infarction (STEMI), non-STEMI, and type 1 MI or type 2 MI. A total of 421 first MI events in the CANVAS Programme and 178 first MI events in the CREDENCE trial were recorded (83 fatal, 128 STEMI, 431 non-STEMI, and 40 unknown). No benefit of canagliflozin compared with placebo on time to first MI event was observed [hazard ratio (HR) 0.89; 95% confidence interval (CI) 0.75, 1.05]. Canagliflozin was associated with lower risk for non-STEMI (HR 0.78; 95% CI 0.65, 0.95) but suggested a possible increase in STEMI (HR 1.55; 95% CI 1.06, 2.27), with no difference in risk of type 1 or type 2 MI. There was no change in fatal MI (HR 1.22, 95% CI 0.78, 1.93). Conclusion Canagliflozin was not associated with a reduction in overall MI in the pooled CANVAS Programme and CREDENCE trial population. The possible differential effect on STEMI and Non-STEMI observed in the CANVAS cohort warrants further investigation. Trial registration ClinicalTrials.gov identifiers: NCT01032629, NCT01989754, and NCT02065791.

Various metabolic processes in the body oscillate throughout the natural day, driven by a biological clock. Circadian rhythms are also influenced by time cues from the environment (light exposure) and behaviour (eating and exercise). Recent evidence from diurnal- and circadian-rhythm studies indicates rhythmicity in various circulating metabolites, insulin secretion and -sensitivity and energy expenditure in metabolically healthy adults. These rhythms have been shown to be disturbed in adults with obesity-related metabolic disturbances. Moreover, eating and being (in)active at a time that the body is not prepared for it, as in night-shift work, is related to poor metabolic outcomes. These findings indicate the relevance of 24-h metabolism in obesity-related metabolic alterations and have also led to novel strategies, such as timing of food intake and exercise, to reinforce the circadian rhythm and thereby improving metabolic health. This review aims to deepen the understanding of the influence of the circadian system on metabolic processes and obesity-related metabolic disturbances and to discuss novel time-based strategies that may be helpful in combating metabolic disease.

Background & Aims Human studies examining associations between circulating levels of insulin-like growth factor 1 (IGF1) and insulin-like growth factor binding protein 3 (IGFBP3) and colorectal cancer risk have reported inconsistent results. We conducted complementary serologic and Mendelian randomization (MR) analyses to determine whether alterations in circulating levels of IGF1 or IGFBP3 are associated with colorectal cancer development. Methods Serum levels of IGF1 were measured in blood samples collected from 397,380 participants from the UK Biobank, from 2006 through 2010. Incident cancer cases and cancer cases recorded first in death certificates were identified through linkage to national cancer and death registries. Complete follow-up was available through March 31, 2016. For the MR analyses, we identified genetic variants associated with circulating levels of IGF1 and IGFBP3. The association of these genetic variants with colorectal cancer was examined with 2-sample MR methods using genome-wide association study consortia data (52,865 cases with colorectal cancer and 46,287 individuals without [controls]) Results After a median follow-up period of 7.1 years, 2665 cases of colorectal cancer were recorded. In a multivariable-adjusted model, circulating level of IGF1 associated with colorectal cancer risk (hazard ratio per 1 standard deviation increment of IGF1, 1.11; 95% confidence interval [CI] 1.05–1.17). Similar associations were found by sex, follow-up time, and tumor subsite. In the MR analyses, a 1 standard deviation increment in IGF1 level, predicted based on genetic factors, was associated with a higher risk of colorectal cancer risk (odds ratio 1.08; 95% CI 1.03–1.12; P = 3.3 × 10–4). Level of IGFBP3, predicted based on genetic factors, was associated with colorectal cancer risk (odds ratio per 1 standard deviation increment, 1.12; 95% CI 1.06–1.18; P = 4.2 × 10–5). Colorectal cancer risk was associated with only 1 variant in the IGFBP3 gene region (rs11977526), which also associated with anthropometric traits and circulating level of IGF2. Conclusions In an analysis of blood samples from almost 400,000 participants in the UK Biobank, we found an association between circulating level of IGF1 and colorectal cancer. Using genetic data from 52,865 cases with colorectal cancer and 46,287 controls, a higher level of IGF1, determined by genetic factors, was associated with colorectal cancer. Further studies are needed to determine how this signaling pathway might contribute to colorectal carcinogenesis., Graphical abstract

Emerging data highlighting gut microbiome influences on health support evaluation of how microbial fermentation end-products influence postabsorptive systems. This study aimed to investigate the effect of increased propionate status on progesterone profiles and insulin sensitivity in dairy heifers. Eleven Holstein heifers, synchronized in estrus, were assigned to one of two continuous, 5-day IV treatments: sodium propionate (PRO; n = 5) or saline (CON; n = 6). These infusions culminated in a hyperglycemic clamp with daily blood samples for an additional 7 days. Plasma propionate concentrations increased over the first 9 h in PRO heifers, then decreased until day 3 when they matched CON heifers. Maximum plasma progesterone concentrations tended to be greater in PRO heifers than CON heifers (4.19 vs 3.73 ng/mL; P = 0.087). Plateau insulin concentrations in CON animals were significantly greater than those in PRO animals (249.4 ± 25.1 vs 123.9 ± 35.8; P = 0.008) with a trend for an increased insulin sensitivity index in PRO heifers compared to CON heifers (P = 0.06). These changes in plasma propionate clearance leading to increased progesterone response and changes in insulin sensitivity suggest a role for SCFA metabolism in reproductive hormone regulation. Published version

Background Several observational studies have shown that higher insulin levels are associated with an increased risk of cardiovascular disease. If higher endogenous insulin levels are causally related to cardiovascular disease, one might expect an increased risk of cardiovascular disease in patients treated with insulin, as this results in high circulating insulin levels. Such risk elevation might counteract the benefits of tight glucose control. Our objective was to explore the relationship between insulin therapy and cardiovascular disease in Type 1 and Type 2 diabetes mellitus using information from available literature.Summary of comment Several experimental studies in animals and humans support the presence of a harmful effect of insulin on the vascular endothelium. In prospective follow-up studies increased insulin dosage was associated with increased risks of cardiovascular disease, although confounding by indication could not be excluded. Randomized controlled trials in diabetic patients, comparing conventional with intensive glucose-lowering treatment, although showing a reduction in microvascular disease, showed no significant difference in the incidence of cardiovascular disease. The results with respect to exposure to insulin are, however, difficult to interpret due to insufficient information on exposure to insulin levels as well as confounding by glycaemic control and body mass index. In addition, these studies were not designed to address the question whether higher insulin use relates to increased cardiovascular risk.Conclusion Published research provides conflicting evidence as to whether exposure to high levels of exogenous insulin in diabetes mellitus affects the risk of cardiovascular disease. The currently available studies have a number of serious methodological restraints that limit accurate interpretation and conclusions in this area.

The effect of progesterone (P) on pancreatic islet-cell proliferation and function of cyclic and pregnant rats was investigated in vivo. Silastic tubes containing P were inserted s.c. in cyclic rats for 7 or 14 days and in pregnant rats from day 7 to 14, from day 14 to 21 or from day 7 to 21 of pregnancy. 5-Bromo-2-deoxyuridine (BrdU) was infused during the last 24 h of the treatment; the proportion of dividing islet-cells was determined in pancreatic sections, which were immunostained for BrdU. Islet-cell function was determined by measuring glucose and insulin response to a standard intravenous glucose challenge. P treatment increased P and 20 alpha-dihydroprogesterone (20 alpha-OHP) levels in cyclic rats; in pregnant rats, only the plasma levels of 20 alpha-OHP were elevated. Both 7 and 14 days of P treatment stimulated islet-cell proliferation in cyclic rats. In pregnant rats, P treatment increased islet-cell proliferation on day 14, but not on day 21 after either 7 or 14 days of P treatment. P did not affect plasma lactogenic activity in pregnant rats; plasma concentrations of prolactin were decreased after 14 days of P treatment in cyclic rats, but were not affected in pregnant rats. P treatment had no effect on glucose tolerance and glucose-stimulated insulin secretion in any of the groups. It was concluded that: 1, in vivo P stimulates islet-cell proliferation, but does not affect islet-cell function, 2. the stimulatory effects of P are indirect and possibly mediated by the P metabolite 20 alpha-OHP and 3. at the end of gestation, stimulation of islet-cell proliferation is inhibited by some factor, which is not identical to P.

OBJECTIVES: The aim of this study is to present age- and sex-specific reference values of insulin, glucose, glycosylated haemoglobin (HbA1c) and the homeostasis model assessment to quantify insulin resistance (HOMA-IR) for pre-pubertal children. METHODS: The reference population consists of 7074 normal weight 3- to 10.9-year-old pre-pubertal children from eight European countries who participated in at least one wave of the IDEFICS ('identification and prevention of dietary- and lifestyle-induced health effects in children and infants') surveys (2007-2010) and for whom standardised laboratory measurements were obtained. Percentile curves of insulin (measured by an electrochemiluminescence immunoassay), glucose, HbA1c and HOMA-IR were calculated as a function of age stratified by sex using the general additive model for location scale and shape (GAMLSS) method. RESULTS: Levels of insulin, fasting glucose and HOMA-IR continuously show an increasing trend with age, whereas HbA1c shows an upward trend only beyond the age of 8 years. Insulin and HOMA-IR values are higher in girls of all age groups, whereas glucose values are slightly higher in boys. Median serum levels of insulin range from 17.4 and 13.2 pmol l- 1 in 3- < 3.5-year-old girls and boys, respectively, to 53.5 and 43.0 pmol l - 1 in 10.5- < 11-year-old girls and boys. Median values of glucose are 4.3 and 4.5 mmol l - 1 in the youngest age group and 49.3 and 50.6 mmol l - 1 in the oldest girls and boys. For HOMA-IR, median values range from 0.5 and 0.4 in 3- < 3.5-year-old girls and boys to 1.7 and 1.4 in 10.5- < 11-year-old girls and boys, respectively. CONCLUSIONS: Our study provides the first standardised reference values for an international European children's population and provides the, up to now, largest data set of healthy pre-pubertal children to model reference percentiles for markers of insulin resistance. Our cohort shows higher values of Hb1Ac as compared with a single Swedish study while our percentiles for the other glucose metabolic markers are in good accordance with previous studies.

Obesity is often accompanied by alterations in both sympathetic and parasympathetic autonomic functions. The present paper summarizes the results of a number of studies designed to investigate autonomic functioning in normal, genetically, and experimentally obese rats, Particular emphasis is given to autonomic functioning and dysfunctioning in relation to the processes that are involved in the regulation of peripheral energy substrate homeostasis, It is concluded that alterations in autonomic regulation in obesity are determined by causal factors such as overeating, genetic make-up, age and/or the duration of obesity.

Obesity is often accompanied by alterations in both sympathetic and parasympathetic autonomic functions. The present paper summarizes the results of a number of studies designed to investigate autonomic functioning in normal, genetically, and experimentally obese rats, Particular emphasis is given to autonomic functioning and dysfunctioning in relation to the processes that are involved in the regulation of peripheral energy substrate homeostasis, It is concluded that alterations in autonomic regulation in obesity are determined by causal factors such as overeating, genetic make-up, age and/or the duration of obesity.

Islet isograft function was analyzed after transplantation of 4 well-defined endocrine volumes (12.5%, 25%, 50%, and 100% of the endocrine volume in the normal adult rat pancreas) to 3 different sites (kidney, liver, and spleen). Graft function was tested in unanesthetized, unstressed rats by the responses to glucose infusion and to a meal, All animals with grafts greater than or equal to 25% of the endocrine volume of the rat pancreas returned to normoglycemia after transplantation. The minimal graft volume for restoring normoglycemia is probably between 12.5% and 25%, since also a small number of grafts of 12.5% were successful. At 1 month, basal glucose and insulin levels were similar to those of controls in rats with grafts to the spleen, but higher in rats with grafts to the kidney or liver. Irrespective of the transplantation site, recipients had higher glucose and lower insulin levels than controls in response to glucose infusion. In response to a meal, however, only the first-phase insulin response was reduced, but the total insulin output during the entire test was similar to that of controls. Graft performance was found to be graft-size dependent. Results of tests performed at 2 months showed a tendency of increasing responsiveness compared with the results of tests at 1 month.

We have analysed the graft function of rat islet isografts of identical and well-defined endocrine volumes after transplantation to three different sites (kidney, liver and spleen). Graft endocrine mass was determined by measuring the total islet volume prior to transplantation and was chosen to be similar to the endocrine volume in the normal adult rat pancreas. Graft function was tested in unanaesthetized, unstressed rats by the responses to glucose infusion and to a meal. All transplanted animals returned to normoglycaemia within one week after transplantation. At one month, basal glucose and insulin levels were similar to controls in rats with grafts to the spleen, but higher in rats with grafts to the kidney or liver. Irrespective of the transplantation site, recipients had higher glucose and lower insulin levels than controls in response to glucose infusion, but in response to a meal these differences from normal were less obvious. Finally, recipients showed both an acute insulin response to glucose infusion as well as a pre-absorptive insulin release after food ingestion, irrespective of the transplantation site. Our findings indicate that the insulin response to glucose infusion and to a meal is quantitatively reduced, but qualitatively intact after transplantation to the kidney liver or spleen.

The present study examined, at identical daily nutrient intakes, the impact of separating protein and lactose intakes across two daily meals on the metabolic and endocrine status in heavy veal calves. Calves were assigned to one of six degrees of separating protein and lactose over the two meals (termed nutrient synchrony, SYN 1-6; 6 calves/treatment). They were fed the protein-rich (P-)meal and the lactose-rich (L-)meal at 06:00 and 18:00h, respectively, or vice versa. At SYN 1, calves were fed with 50% of the daily protein and 50% of the daily lactose intake in each meal. Protein and lactose were iso-energetically exchanged between the two daily meals from SYN I to 6. At SYN 6, 85% of the daily protein and 20% of the daily lactose was fed in the P-meal and the remainder in the L-meal. Blood samples were collected hourly during 24 h. Mean 24 h glucose concentrations increased and insulin concentrations decreased from SYN I to 6. Postprandial 5 h areas under concentration curves (AUC(0-5h)) of glucose increased with increasing meal lactose content. AUC(0-5h) of non-esterified fatty acids increased after P- and L-meals from SYN I to 6. Urea concentrations increased after L-meals from SYN I to 6, but decreased after P-meals from SYN I to 6. Insulin AUC(0-5h) decreased after L-meals and after P-meals from SYN I to 6. Nutrient asynchrony did not affect insulin-like growth factor- 1, glucagon, growth hormone, leptin, 3,5,3'-triiodothyronine and thyroxine. In conclusion, separation of protein and lactose intake over meals inhibited insulin responses to a lactose-rich meal in heavy veal calves despite high plasma glucose concentrations. (c) 2007 Elsevier Inc. All rights reserved.

Background Several observational studies have shown that higher insulin levels are associated with an increased risk of cardiovascular disease. If higher endogenous insulin levels are causally related to cardiovascular disease, one might expect an increased risk of cardiovascular disease in patients treated with insulin, as this results in high circulating insulin levels. Such risk elevation might counteract the benefits of tight glucose control. Our objective was to explore the relationship between insulin therapy and cardiovascular disease in Type 1 and Type 2 diabetes mellitus using information from available literature. Summary of comment Several experimental studies in animals and humans support the presence of a harmful effect of insulin on the vascular endothelium. In prospective follow-up studies increased insulin dosage was associated with increased risks of cardiovascular disease, although confounding by indication could not be excluded. Randomized controlled trials in diabetic patients, comparing conventional with intensive glucose-lowering treatment, although showing a reduction in microvascular disease, showed no significant difference in the incidence of cardiovascular disease. The results with respect to exposure to insulin are, however, difficult to interpret due to insufficient information on exposure to insulin levels as well as confounding by glycaemic control and body mass index. In addition, these studies were not designed to address the question whether higher insulin use relates to increased cardiovascular risk. Conclusion Published research provides conflicting evidence as to whether exposure to high levels of exogenous insulin in diabetes mellitus affects the risk of cardiovascular disease. The currently available studies have a number of serious methodological restraints that limit accurate interpretation and conclusions in this area. Diabet. Med. 22, 118–126 (2005)

The effect of progesterone (P) on pancreatic islet-cell proliferation and function of cyclic and pregnant rats was investigated in vivo. Silastic tubes containing P were inserted s.c. in cyclic rats for 7 or 14 days and in pregnant rats from day 7 to 14, from day 14 to 21 or from day 7 to 21 of pregnancy. 5-Bromo-2-deoxyuridine (BrdU) was infused during the last 24 h of the treatment; the proportion of dividing islet-cells was determined in pancreatic sections, which were immunostained for BrdU. Islet-cell function was determined by measuring glucose and insulin response to a standard intravenous glucose challenge. P treatment increased P and 20 alpha-dihydroprogesterone (20 alpha-OHP) levels in cyclic rats; in pregnant rats, only the plasma levels of 20 alpha-OHP were elevated. Both 7 and 14 days of P treatment stimulated islet-cell proliferation in cyclic rats. In pregnant rats, P treatment increased islet-cell proliferation on day 14, but not on day 21 after either 7 or 14 days of P treatment. P did not affect plasma lactogenic activity in pregnant rats; plasma concentrations of prolactin were decreased after 14 days of P treatment in cyclic rats, but were not affected in pregnant rats. P treatment had no effect on glucose tolerance and glucose-stimulated insulin secretion in any of the groups. It was concluded that: 1, in vivo P stimulates islet-cell proliferation, but does not affect islet-cell function, 2. the stimulatory effects of P are indirect and possibly mediated by the P metabolite 20 alpha-OHP and 3. at the end of gestation, stimulation of islet-cell proliferation is inhibited by some factor, which is not identical to P.

Obesity is often accompanied by alterations in both sympathetic and parasympathetic autonomic functions. The present paper summarizes the results of a number of studies designed to investigate autonomic functioning in normal, genetically, and experimentally obese rats, Particular emphasis is given to autonomic functioning and dysfunctioning in relation to the processes that are involved in the regulation of peripheral energy substrate homeostasis, It is concluded that alterations in autonomic regulation in obesity are determined by causal factors such as overeating, genetic make-up, age and/or the duration of obesity.

Islet isograft function was analyzed after transplantation of 4 well-defined endocrine volumes (12.5%, 25%, 50%, and 100% of the endocrine volume in the normal adult rat pancreas) to 3 different sites (kidney, liver, and spleen). Graft function was tested in unanesthetized, unstressed rats by the responses to glucose infusion and to a meal, All animals with grafts greater than or equal to 25% of the endocrine volume of the rat pancreas returned to normoglycemia after transplantation. The minimal graft volume for restoring normoglycemia is probably between 12.5% and 25%, since also a small number of grafts of 12.5% were successful. At 1 month, basal glucose and insulin levels were similar to those of controls in rats with grafts to the spleen, but higher in rats with grafts to the kidney or liver. Irrespective of the transplantation site, recipients had higher glucose and lower insulin levels than controls in response to glucose infusion. In response to a meal, however, only the first-phase insulin response was reduced, but the total insulin output during the entire test was similar to that of controls. Graft performance was found to be graft-size dependent. Results of tests performed at 2 months showed a tendency of increasing responsiveness compared with the results of tests at 1 month.

We have analysed the graft function of rat islet isografts of identical and well-defined endocrine volumes after transplantation to three different sites (kidney, liver and spleen). Graft endocrine mass was determined by measuring the total islet volume prior to transplantation and was chosen to be similar to the endocrine volume in the normal adult rat pancreas. Graft function was tested in unanaesthetized, unstressed rats by the responses to glucose infusion and to a meal. All transplanted animals returned to normoglycaemia within one week after transplantation. At one month, basal glucose and insulin levels were similar to controls in rats with grafts to the spleen, but higher in rats with grafts to the kidney or liver. Irrespective of the transplantation site, recipients had higher glucose and lower insulin levels than controls in response to glucose infusion, but in response to a meal these differences from normal were less obvious. Finally, recipients showed both an acute insulin response to glucose infusion as well as a pre-absorptive insulin release after food ingestion, irrespective of the transplantation site. Our findings indicate that the insulin response to glucose infusion and to a meal is quantitatively reduced, but qualitatively intact after transplantation to the kidney liver or spleen.