Cross-sectional and prospective associations between abdominal adiposity and proinsulin concentration

Is the nuclear factor kappa-b (NF-κB) pathway and inflammatory status associated with colorectal cancer?

BACKGROUND

Although genetic predisposition has a role in the etiology of colorectal cancer, there are many other factors that affect its development. In this study, it was aimed to evaluate the NF-κB pathway, inflammatory status and dietary antioxidant capacity in individuals with colorectal cancer.

METHODS

The study was carried out with 40 male subjects diagnosed with colorectal cancer aged between 39-65, years and a control group of the same number of healthy men. Subjects in the case and control groups were subdivided according to body mass index (BMI), as normal (BMI 20-24.9 kg/m²) or overweight/obese (BMI ≥25 kg/m²).

RESULTS

At the end of the study, NF-κB and interleukin-22 levels were higher in the case group, but no significant difference was found between the groups. Interleukin-23 and 8-Hydroxy-2-deoxyguanosine levels in the case group classified as overweight/obese according to BMI were significantly higher than in the control group (P = 0.001 and P < 0.001, respectively). Considering diet antioxidant capacity, it was higher in individuals in the control group than in the case group. However, there was no significant difference between the groups.

CONCLUSION

Inflammatory status and reduced dietary antioxidant capacity are risk factors in the development of colorectal cancer.

Waist Circumference Might Be a Predictor of Primary Liver Cancer: A Population-Based Cohort Study

Background: Waist circumference, as an indicator of central adiposity, has been identified as an important predictor of several specific cancers such as colorectal cancer and gastroesophageal cancer risk, however, a consensus regarding the association between waist circumference and primary liver cancer (PLC) risk has not been reached.

Methods: A total of 104,825 males participating in the health checkup were included in the Kailuan male cohort study (2006–2015). Information on demographic and socioeconomic characteristics, lifestyle, medical records, and anthropometric measures were collected. Restricted cubic spline (RCS) and Cox proportional hazards regression models were used to estimate the hazard ratio (HR) and 95% confidence interval (CI) of association between waist circumference and the risk of PLC in males.

Results: During a median of 8.9 years of follow-up, 346 PLC cases were newly diagnosed in the cohort. The RCS model showed a U-shaped association between waist circumference and PLC risk (P-overall = 0.019, P-non-linear = 0.017). Overally, males with both high waist circumference (HR_Q5vs.Q3 = 1.98, 95%CI: 1.39–2.82) and low waist circumference (HR_Q1vs.Q3 = 1.52, 95%CI: 1.02–2.27) had an increased risk of PLC. Especially, the U-shaped association between waist circumference and PLC risk tended to be strengthened among subjects with hepatitis B surface antigen (HBsAg) negativity (HR_Q5vs.Q3 = 2.39, 95%CI: 1.43–3.98; HR_Q1vs.Q3 = 2.27, 95%CI = 1.29–4.01).

Conclusions: Waist circumference might be an independent predictor of PLC risk in males, especially for subjects with HBsAg negativity. Controlling waist circumference in an appropriate range might be an effective primary prevention to decrease PLC risk.

The Role of C-Peptide as Marker of Cardiometabolic Risk in Women With Polycystic Ovary Syndrome: A Controlled Study

Background

The aim of this study was to examine the role of C-peptide as a biological marker of cardiometabolic risk in polycystic ovary syndrome (PCOS).

Methods

This case-control study enrolled 385 PCOS patients and 240 normal cycling women. Anthropometric and clinical variables were taken at first visit. Fasting C-peptide, glucose, lipids, and hormone measurements were performed. Simple and multiple correlations between C-peptide and other variables associated with dysmetabolism and cardiovascular disease were examined.

Results

C-peptide was well correlated with several anthropometric, metabolic, and endocrine parameters. In PCOS patients, stepwise multiple regression including C-peptide as the criterion variable and other predictors of cardiovascular disease risk provided a significant model in which the fasting C-peptide/glucose ratio, glucose, body weight, and free estrogen index (FEI) were retained (adjusted R² = 0.988, F = 7.161, P = 0.008).

Conclusion

C-peptide levels alone or combined with C-peptide/glucose ratio, glucose, body weight, and FEI provided a significant model to identify PCOS patients with higher risk of future cardiometabolic diseases.

Hyperproinsulinemia in obesity and in type 2 diabetes and its relation to cardiovascular disease

Disproportionately elevated fasting levels of proinsulin immunoreactive material (PIM)relative to insulin immunoreactivity (IRI) are a well-established abnormality in type 2 diabetes. Thesignificance of this abnormality has been investigated and discussed in several studies. Areas covered: The present review focuses on the role of proinsulin and its conversion intermediates inthe development of type 2 diabetes, obesity and insulin resistance, and the potential role as a marker ofcardiovascular risk, including the most important studies in this field. Expert commentary: The composition of plasma PIM is heterogeneous comprising des(31,32)-proinsulin,intact proinsulin and small amounts of des(64,65)-proinsulin. Disproportionate hyperproinsulinemiaseems to occur early in the development and before the diagnosis of type 2 diabetes, and seemsassociated to disease progression. Obesity and insulin resistance does not influence fasting PIM/IRI levels in type 2 diabetes. Fasting PIM/IRI levels in type 2 diabetes are closely associated with the degree of impairment in insulin secretory capacity. Different type 2 diabetes alleles have been described associated with elevated PIM/IRI levels. Recent data suggests that proinsulin and its conversion intermediates may have a role as markers of increased risk of cardiovascular disease in glucose intolerance and type 2 diabetes.

Obesity, adiposity, physical fitness and activity levels in cree children

OBJECTIVES

To describe the levels of obesity, adiposity measures, physical activity and fitness in Cree children aged 9-12 years.

STUDY DESIGN

Cross-sectional survey.

METHODS

The study took place in northern Quebec, Canada. Height, body mass, waist circumference and five skinfold thicknesses were measured. Physical activity was assessed by having children wear a pedometer for two days. Children performed the 20-metre shuttle run test (SRT) to determine their physical fitness level.

RESULTS

Of 82 participating children, 33% were overweight (but not obese) and 38% were obese according to an international reference. The mean sum of five skinfold measures exceeded the 95th percentile of Canadian children. Compared with the Third National Health and Nutrition Examination Survey, the majority of children exceeded the 85th percentile for waist circumference (62%) and at the suprailiac (80%), subscapular (72%), and triceps (54%) skinfold sites. 90% of children scored below the 20th percentile in the SRT compared with normative data from Quebec children. Based on pedometer scores, only 49% of children were sufficiently active.

CONCLUSIONS

There is a high prevalence of overweight and central adiposity in this population, with low physical activity and fitness levels. This profile may result in adverse health outcomes.

Long-term status and change of body fat distribution, and risk of colorectal cancer: a prospective cohort study

BACKGROUND

Although obesity has been linked to an increased risk of colorectal cancer (CRC), the risk associated with long-term status or change of body fat distribution has not been fully elucidated.

METHODS

Using repeated anthropometric assessments in the Nurses' Health Study and Health Professionals Follow-up Study, we prospectively investigated cumulative average waist circumference, hip circumference and waist-to-hip ratio, as well as their 10-year changes over adulthood, in relation to CRC risk over 23-24 years of follow-up. Cox proportional hazards models were used to calculate the hazard ratio (HR) and 95% confidence interval (CI).

RESULTS

High waist circumference, hip circumference and waist-to-hip ratio were all associated with a higher CRC risk in men, even after adjusting for body mass index. The association was attenuated to null in women after adjusting for body mass index. Ten-year gain of waist circumference was positively associated with CRC risk in men (P for trend = 0.03), but not in women (P for trend = 0.34).Compared with men maintaining their waist circumference, those gaining waist circumference by ≥ 10 cm were at a higher risk of CRC, with a multivariable-adjusted HR of 1.59 (95% CI, 1.01-2.49). This association appeared to be independent of weight change.

CONCLUSIONS

Abdominal adiposity, independent of overall obesity, is associated with an increased CRC risk in men but not in women. Our findings also provide the first prospective evidence that waist circumference gain during adulthood may be associated with higher CRC risk in men, thus highlighting the importance of maintaining a healthy waist for CRC prevention.

Elevated C-peptide and insulin predict increased risk of colorectal adenomas in normal mucosa

BACKGROUND

Lower concentrations of the insulin-like growth factor binding protein-1 (IGFBP-1) and elevated concentrations of insulin or C-peptide have been associated with an increase in colorectal cancer risk (CRC). However few studies have evaluated IGFBP-1 and C-peptide in relation to adenomatous polyps, the only known precursor for CRC.

METHODS

Between November 2001 and December 2002, we examined associations between circulating concentrations of insulin, C-peptide, IGFBP-1 and apoptosis among 190 individuals with one or more adenomatous polyps and 488 with no adenomatous polyps using logistic regression models.

RESULTS

Individuals with the highest concentrations of C-peptide were more likely to have adenomas (OR = 2.2, 95% CI 1.4-4.0) than those with the lowest concentrations; associations that appeared to be stronger in men (OR = 4.4, 95% CI 1.7-10.9) than women. Individuals with high insulin concentrations also had a higher risk of adenomas (OR = 3.5, 95% CI 1.7-7.4), whereas higher levels of IGFBP-1 were associated with a reduced risk of adenomas in men only (OR = 0.3, 95% CI 0.1-0.7). Overweight and obese individuals with higher C-peptide levels (>1(st) Q) were at increased risk for lower apoptosis index (OR = 2.5, 95% CI 0.9-7.1), an association that remained strong in overweight and obese men (OR = 6.3, 95% CI 1.0-36.7). Higher levels of IGFBP-1 in overweight and obese individuals were associated with a reduced risk of low apoptosis (OR = 0.3, 95% CI 0.1-1.0).

CONCLUSIONS

Associations between these peptides and the apoptosis index in overweight and obese individuals, suggest that the mechanism by which C-peptide could induce adenomas may include its anti-apoptotic properties. This study suggests that hyperinsulinemia and IGF hormones predict adenoma risk, and that outcomes associated with colorectal carcinogenesis maybe modified by gender.

The impact of insulin resistance on proinsulin secretion in pregnancy: hyperproinsulinemia is not a feature of gestational diabetes

OBJECTIVE

Excessive secretion of the insulin precursor proinsulin, as manifested by an increased serum proinsulin-to-insulin ratio, has been associated with beta-cell dysfunction. In women with gestational diabetes mellitus (GDM), previous studies of the proinsulin-to-insulin ratio have yielded conflicting results, despite the presence of beta-cell dysfunction. The interpretation of the proinsulin-to-insulin ratio, however, may be confounded by the variable effects of hepatic insulin extraction. Thus, we sought to determine whether GDM is characterized by relative hyperproinsulinemia as measured by the proinsulin-to-C-peptide ratio, an alternate measure of proinsulin secretion that is not affected by hepatic insulin extraction.

RESEARCH DESIGN AND METHODS

Serum proinsulin, C-peptide, and insulin were measured in a cross-sectional study of 180 women undergoing oral glucose tolerance tests (OGTTs) in the late second or early third trimester. Based on the OGTT, participants were stratified into three groups: 1) normal glucose tolerance (NGT; n = 93), 2) impaired glucose tolerance (IGT; n = 39), and 3) GDM (n = 48). Insulin sensitivity (IS) was measured using the IS(OGTT) index of Matsuda and DeFronzo, which has been previously validated in pregnant women.

RESULTS

There were no significant differences in mean fasting proinsulin-to-C-peptide ratio between the three glucose tolerance groups (NGT, 0.024; IGT, 0.022; GDM, 0.019; P = 0.4). Furthermore, adjustment for age, weeks' gestation, prepregnancy BMI, ethnicity, previous GDM, and family history of diabetes did not reveal any association between the proinsulin-to-C-peptide ratio and glucose tolerance status. Using Spearman univariate correlation analysis, fasting proinsulin-to-C-peptide ratio was significantly correlated with IS(OGTT) (r = 0.29, P < 0.0001) and inversely related to the homeostasis model assessment of insulin resistance (r = -0.36, P < 0.0001) and prepregnancy BMI (r = -0.23, P < 0.005). On multiple linear regression analysis, IS(OGTT) emerged as the strongest independent correlate of the dependent variable proinsulin-to-C-peptide ratio. Furthermore, after adjustment for potential covariates, a stepwise decrease in proinsulin-to-C-peptide ratio was observed per decreasing tertile of IS(OGTT) (trend P = 0.0019), consistent with enhanced efficiency of proinsulin processing (i.e., reduced proinsulin-to-C-peptide ratio) as insulin resistance increases.

CONCLUSIONS

GDM is not independently associated with hyperproinsulinemia as measured by the proinsulin-to-C-peptide ratio. Instead, in pregnant women, increased insulin resistance is associated with decreased proinsulin-to-C-peptide ratio, independently of glucose tolerance status. These data suggest that relative proinsulin secretion in late pregnancy is primarily related to insulin resistance and does not necessarily reflect beta-cell function.

Insulin sensitization early after menarche prevents progression from precocious pubarche to polycystic ovary syndrome

OBJECTIVE

Girls with low birth weight (LBW) and with a history of precocious pubarche in childhood (PP) are at high risk of polycystic ovary syndrome (PCOS) in adolescence. In formerly LBW-PP girls, we examined whether initiation of insulin sensitization therapy early after menarche could prevent progression of PCOS features. Study design Twenty-four girls, small at term birth (mean weight, 2.4 kg), who presented with PP (at mean age 6.7 years) and were currently (mean age, 12.4 years) postmenarcheal, with hyperinsulinemic hyperandrogenemia but nonobese, were randomly assigned to receive metformin (850 mg/d) or no treatment for 12 months. Six-month fasting blood samples were collected, and body composition was assessed by dual-energy x-ray absorptiometry. In addition, overnight growth hormone (GH) and gonadotropin secretion was analyzed in 10 girls (6 treated; 4 untreated) at 0 and 6 months.

RESULTS

At baseline, compared with healthy control subjects, LBW-PP girls had dyslipidemia, excess truncal fat, reduced lean body mass, and increased insulin-like growth factor-I and GH levels. In untreated girls, insulin sensitivity, serum androgens, lipids, total and truncal fat mass, and lean body mass significantly diverged further from normal over 12 months. In metformin-treated girls, all these abnormalities significantly reversed within 6 months, and body composition continued to improve between 6 and 12 months.

CONCLUSIONS

Early metformin therapy prevents progression from PP to PCOS in a high-risk group of formerly LBW girls. This confirms the key role of hyperinsulinemic insulin resistance in the ontogeny of PCOS. Furthermore, normalization of body composition, lipid profiles, and GH secretion could reduce long-term cardiovascular risk.

Effects of developmental and adult androgens on male abdominal adiposity

We present results from 42 gay men who completed a survey including self-measurement of waist circumference, height, and weight, in addition to providing saliva samples for the assay of testosterone, and a photocopy of the right hand for the measure of second-to-fourth digit length ratio (2D:4D), proposed as a means of approximating androgenic effects during development. The analyses were conducted as a test of the recent hypothesis, proposed by Abbott et al. ([2002] J Endocrinol 174:1-5), that high prenatal androgen exposure causes greater deposition of fat on the abdomen relative to other depots. We found support for this hypothesis in men, albeit in a limited sample and with self-reported and self-collected data.

Low-dose flutamide-metformin therapy reverses insulin resistance and reduces fat mass in nonobese adolescents with ovarian hyperandrogenism

Ovarian hyperandrogenism is a common disorder often presenting post menarche with anovulatory oligomenorrhea and signs of androgen excess. Associated hyperinsulinemic insulin resistance, dyslipidemia, and central fat excess herald long-term disease risk. Combined antiandrogen (flutamide 250 mg/d) and insulin-sensitizing (metformin) therapy has beneficial effects, in particular on dyslipidemia and androgen excess in young women. We studied the effects of low-dose flutamide-metformin combination on metabolic variables and body composition in adolescent girls with ovarian hyperandrogenism. Thirty teenage girls (age range, 13.6-18.6 yr) with hyperinsulinemic hyperandrogenism participated in a 12-month pilot study with a 3-month off-treatment phase and a 9-month treatment phase (randomized sequence) on combined flutamide (125 mg/d) and metformin (1275 mg/d). Body composition was assessed by dual-energy x-ray absorptiometry; endocrine-metabolic state and ovulation rate were screened every 3 months. Insulin sensitivity was assessed by homeostasis model assessment (HOMA). Overnight GH and LH profiles were obtained pretreatment and after 6 months on treatment (n = 8). Over the 3-month pretreatment control phase (n = 14) all study indices were unchanged. Flutamide-metformin treatment (n = 30) was followed within 3 months by marked decreases in hirsutism score and serum androgens, by a more than 50% increase in insulin sensitivity and by a less atherogenic lipid profile (all P < 0.0001). After 9 months on flutamide-metformin, body fat decreased by 10%, with a preferential 20% loss of abdominal fat; conversely lean body mass increased, and total body weight remained unchanged; ovulation rate increased from 7-87% after 9 months. Baseline GH hypersecretion and elevated serum IGF-1 normalized after 6 months on flutamide-metformin. Within 3 months post treatment (n = 16), a rebound was observed for all assessed indices. In conclusion, in teenage girls with ovarian hyperandrogenism, low-dose combined flutamide-metformin therapy attenuated a spectrum of abnormalities, including insulin resistance and hyperlipidemia. Improved insulin sensitivity and reduced androgen activity led to a marked redistribution of body fat and lean mass, resulting in a more feminine body shape.

Fat distribution in non-obese girls with and without precocious pubarche: central adiposity related to insulinaemia and androgenaemia from prepuberty to postmenarche

OBJECTIVE

Precocious pubarche (PP) in girls is associated with hyperinsulinaemia and dyslipidaemia of prepubertal onset, and with ovarian hyperandrogenism and ovulatory dysfunction in adolescence, particularly if they also had prenatal growth restraint and postnatal growth acceleration. Hyperinsulinaemia may be the pathogenic key factor, possibly amplified by hyperandrogenaemia. While such PP girls do not have increased body mass index (BMI), we hypothesized that body fat mass and fat distribution may differ between PP girls and matched controls, and may relate to insulin and androgen levels.

PATIENTS AND DESIGN

Sixty-seven PP girls (age range 6.0-18.0 years) and 65 control girls matched for age and pubertal stage (5.9-18.0 years) had height, weight, waist and hip circumferences measured, and dual-energy X-ray absorptiometry (DXA) assessment of total body fat mass, and fat mass in abdominal and truncal regions. All girls had fasting plasma glucose, serum insulin, lipids, testosterone and SHBG levels measured; PP girls also had a standard 2-h oral glucose tolerance test (oGTT).

RESULTS

Despite no differences in BMI, PP girls had significantly larger waist circumference, waist-to-hip ratio, total fat mass, percentage fat mass, abdominal fat mass, and truncal fat mass vs. controls in each pubertal stage. Overall, fasting insulin levels, free androgen index (FAI) and blood lipid levels were more closely related to central fat than to total body fat mass. In a multiple regression analysis, truncal fat mass was independently related to both fasting insulin (P = 0.009) and FAI (P < 0.0001). Abdominal fat mass was inversely related to birthweight (r = -0.25, P = 0.001). In PP girls, central fat mass was positively related to insulin levels after oGTT (truncal fat vs. 30 min insulin; r = 0.46, P < 0.0005).

CONCLUSIONS

Precocious pubarche girls had excess total body and central fat mass throughout all pubertal stages, and increased central fat was related to hyperinsulinaemia and hyperandrogenaemia. It remains to be verified whether body composition in PP girls can be normalized by insulin-sensitization and/or antiandrogen therapy.