Diagnosing insulin resistance in the general population

Feed restriction during pregnancy/lactation induces programmed changes in lipid, adiponectin and leptin levels with gender differences in rat offspring

OBJECTIVE

We investigated the effects of fetal undernutrition during pregnancy/lactation on visceral fat, lipid profiles, leptin and adiponectin, and examined the gender differences between males and females.

STUDY DESIGN

From 10 d to term gestation and through lactation, control pregnant rats were fed ad libitum (AdLib) food, whereas study rats were 50% food restricted (FR). Cross-fostering techniques were used to examine the effects of FR during pregnancy and lactation periods. Lipid profiles, leptin and adiponectin were determined in offspring at ages 3 weeks and 6 months. We also measured the amount of visceral fat in the offspring.

RESULTS

The amount of visceral fat in the 6-month-old FR/AdLib offspring was higher than that in the control (p < 0.05). Among the 6-month-old offspring, triglyceride and leptin levels were higher in FR/AdLib offspring than those in the controls (p < 0.05). The female offspring had higher levels of triglyceride, HDL-cholesterol, and adiponectin and the male offspring had higher levels of LDL cholesterol and leptin.

CONCLUSION

Fetal undernutrition only during pregnancy resulted in obese offspring, higher levels of plasma triglyceride and leptin with gender differences.

Serum levels of the adipokine progranulin depend on renal function

OBJECTIVE

Progranulin has recently been introduced as a novel adipokine inducing insulin resistance and obesity. In the current study, we investigated renal elimination, as well as association of the adipokine with markers of the metabolic syndrome.

RESEARCH DESIGN AND METHODS

Progranulin serum levels were quantified by enzyme-linked immunosorbent assay and correlated to anthropometric and biochemical parameters of renal function and glucose and lipid metabolism, as well as inflammation, in 532 patients with stages 1-5 of chronic kidney disease (CKD).

RESULTS

Median serum progranulin levels adjusted for age, sex, and BMI were significantly different between CKD stages with highest values detectable in stage 5 (stage 1, 58.3 µg/L; stage 2, 63.0 µg/L; stage 3, 65.4 µg/L; stage 4, 68.8 µg/L; and stage 5, 90.6 µg/L). Furthermore, CKD stage was the strongest independent predictor of circulating progranulin in our cohort. In addition, high-sensitivity interleukin-6 and adiponectin remained significantly and independently correlated with the adipokine.

CONCLUSIONS

We demonstrate that progranulin serum levels increase with deteriorating renal function. These findings are in accordance with the hypothesis that renal clearance is a major elimination route for circulating progranulin. Furthermore, the adipokine is positively and independently associated with markers of inflammation and adiponectin.

Physical activity, sedentary behaviour and metabolic control following stroke: a cross-sectional and longitudinal study

BACKGROUND

Physical activity and sedentary behaviour are key moderators of cardiovascular disease risk and metabolic control. Despite the importance of a physically active lifestyle, little is known about the effects of stroke on physical activity. We assessed physical activity and sedentary behaviour at three time points following stroke compared to a healthy control group.

METHODS

Physical activity and sedentary behaviour were objectively measured using a portable multi-sensor array in 31 stroke participants (73±9 years, National Institute of Health Stroke Scale 2±2, mobile 10 metres with/without aid) within seven days and at three and six months. Stroke data were compared with an age, sex and body mass index matched healthy control group (n = 31).

RESULTS

Within seven days of stroke, total energy expenditure and physical activity were significantly lower and sedentary time higher in the stroke group compared to controls (total energy expenditure 1840±354 vs. 2220±489 kcal, physical activity 28±32 vs. 79±46 min/day, steps 3111±2290 vs. 7996±2649, sedentary time 1383±42 vs. 1339±44 min/day, p<0.01). At three months physical activity levels had increased (64±58 min/day) but plateaued by six months (66±68 min/day).

CONCLUSIONS

Physical activity levels are reduced immediately post-stroke and remain below recommended levels for health and wellbeing at the three and six month time points. Clinicians should explore methods to increase physical activity and reduce sedentary behaviour in both the acute and later stages following stroke.

A lower degree of PBMC L1 methylation is associated with excess body weight and higher HOMA-IR in the presence of lower concentrations of plasma folate

BACKGROUND

Identification of associations between global DNA methylation and excess body weight (EBW) and related diseases and their modifying factors are an unmet research need that may lead to decreasing DNA methylation-associated disease risks in humans. The purpose of the current study was to evaluate the following; 1) Association between the degree of peripheral blood mononuclear cell (PBMC) L1 methylation and folate, and indicators of EBW, 2) Association between the degree of PBMC L1 methylation and folate, and insulin resistance (IR) as indicated by a higher homeostasis model assessment (HOMA-IR).

METHODS

The study population consisted of 470 child-bearing age women diagnosed with abnormal pap. The degree of PBMC L1 methylation was assessed by pyrosequencing. Logistic regression models specified indicators of EBW (body mass index-BMI, body fat-BF and waist circumference-WC) or HOMA-IR as dependent variables and the degree of PBMC L1 methylation and circulating concentrations of folate as the independent predictor of primary interest.

RESULTS

Women with a lower degree of PBMC L1 methylation and lower plasma folate concentrations were significantly more likely to have higher BMI, % BF or WC (OR = 2.49, 95% CI:1.41-4.47, P = 0.002; OR = 2.49, 95% CI:1.40-4.51, P = 0.002 and OR = 1.98, 95% = 1.14-3.48 P = 0.0145, respectively) and higher HOMA-IR (OR = 1.78, 95% CI:1.02-3.13, P = 0.041).

CONCLUSION

Our results demonstrated that a lower degree of PBMC L1 methylation is associated with excess body weight and higher HOMA-IR, especially in the presence of lower concentrations of plasma folate.

A novel fasting blood test for insulin resistance and prediabetes

BACKGROUND

Insulin resistance (IR) can precede the dysglycemic states of prediabetes and type 2 diabetes mellitus (T2DM) by a number of years and is an early marker of risk for metabolic and cardiovascular disease. There is an unmet need for a simple method to measure IR that can be used for routine screening, prospective study, risk assessment, and therapeutic monitoring. We have reported several metabolites whose fasting plasma levels correlated with insulin sensitivity. These metabolites were used in the development of a novel test for IR and prediabetes.

METHODS

Data from the Relationship between Insulin Sensitivity and Cardiovascular Disease Study were used in an iterative process of algorithm development to define the best combination of metabolites for predicting the M value derived from the hyperinsulinemic euglycemic clamp, the gold standard measure of IR. Subjects were divided into a training set and a test set for algorithm development and validation. The resulting calculated M score, M(Q), was utilized to predict IR and the risk of progressing from normal glucose tolerance to impaired glucose tolerance (IGT) over a 3 year period.

RESULTS

M(Q) correlated with actual M values, with an r value of 0.66. In addition, the test detects IR and predicts 3 year IGT progression with areas under the curve of 0.79 and 0.70, respectively, outperforming other simple measures such as fasting insulin, fasting glucose, homeostatic model assessment of IR, or body mass index.

CONCLUSIONS

The result, Quantose(TM), is a simple test for IR based on a single fasting blood sample and may have value as an early indicator of risk for the development of prediabetes and T2DM.

Analysis of the degree of insulin resistance in post menopausal women by using skin temperature measurements and fasting insulin and fasting glucose levels: a case control study

INTRODUCTION

In addition to being associated with the termination of the reproductive life in women, menopause coincides with an increase in several co-morbidities which include insulin resistance. An increase in the insulin resistance is associated with an increased risk of diabetes, cardiovascular disease and breast cancer.

AIM

To analyze the degree of insulin resistance in post menopausal women by using skin temperature measurements and to confirm the insulin resistance from the fasting insulin and the fasting glucose levels.

METHODS

The insulin insensitivity was assessed by using skin temperature measurements and this was further proved by assessing the fasting insulin and the fasting glucose levels, and by incorporating the values for the Homeostatic model assessment (HOMA) and the Quantitative insulin sensitivity check index (QUICKI).

STATISTICAL ANALYSIS

This was a case control study and the association was found by applying Fischer's exact test and the P value was estimated. The statistical significance was set at p < 0.05. Student's t test was applied to determine the significant difference in the skin temperature measurements.

RESULTS

By using the HOMA index, only 15 subjects out of the 25 post menopausal women were identified to be insulin resistant. 11 of them were also identified by QUICKI. No premenopausal woman from the recruited population showed insulin resistance with the HOMA and the QUICKI indices. The skin temperature measurements showed significant correlations with the HOMA and the QUICKI indices. There was a significant decrease (p value < 0.0001) in the skin temperature in the postmenopausal women as compared to that in the premenopausal women. The mean ± SD was found to be 0.3834 ± 0.1666 in the premenopausal women, and it was 2.192 ± 3.943 in the postmenopausal women.

CONCLUSION

This study suggests a linear correlation between the skin temperature measurements and the insulin resistance. An increased prevalence of insulin resistance was seen in the postmenopausal women as compared to the premenopausal women.

Clinical validation of the quick dynamic insulin sensitivity test

The quick dynamic insulin sensitivity test (DISTq) can yield an insulin sensitivity result immediately after a 30-min clinical protocol. The test uses intravenous boluses of 10 g glucose and 1 U insulin at t = 1 and 11 min, respectively, and measures glucose levels in samples taken at t = 0, 10, 20, and 30 min. The low clinical cost of the protocol is enabled via robust model formulation and a series of population-derived relationships that estimate insulin pharmacokinetics as a function of insulin sensitivity (SI). Fifty individuals underwent the gold standard euglycaemic clamp (EIC) and DISTq within an eight-day period. SI values from the EIC and two DISTq variants (four-sample DISTq and two-sample DISTq30) were compared with correlation, Bland-Altman and receiver operator curve analyses. DISTq and DISTq30 correlated well with the EIC [R = 0.76 and 0.75, and receiver operator curve c-index = 0.84 and 0.85, respectively]. The median differences between EIC and DISTq/DISTq30 SI values were 13% and 22%, respectively. The DISTq estimation method predicted individual insulin responses without specific insulin assays with relative accuracy and thus high equivalence to EIC SI values was achieved. DISTq produced very inexpensive, relatively accurate immediate results, and can thus enable a number of applications that are impossible with established SI tests.

Role of insulin resistance indices in predicting new-onset diabetes after kidney transplantation

New-onset diabetes mellitus (NODAT) is a serious complication following renal transplantation. In this cohort study, we studied 118 nondiabetic renal transplant recipients to examine whether indices of insulin resistance and secretion calculated before transplantation and at 3 months post-transplantation are associated with the development of NODAT within 1 year. We also analysed the long-term impact of early diagnosed NODAT. Insulin indices were calculated using homeostasis model assessment (HOMA) and McAuley's Index. NODAT was diagnosed using fasting plasma glucose. Median follow-up was 11 years. The cumulative incidence of NODAT at 1 year was 37%. By logistic regression, recipient age (per year) was the only significant pretransplant predictor of NODAT (OR 1.04, CI 1.009-1.072), while age (OR 1.04, CI 1.005-1.084) and impaired fasting glucose (OR 2.97, CI 1.009-8.733) were significant predictors at 3 months. Pretransplant and 3-month insulin resistance and secretion indices did not predict NODAT. All-cause mortality was significantly higher in recipients developing NODAT within 1 year compared with those remaining nondiabetic (44% vs. 22%, log-rank P = 0.008). By Cox's regression analysis, age (HR 1.075, CI 1.042-1.110), 1-year creatinine (HR 1.007, CI 1.004-1.010) and NODAT within 3 months (HR 2.4, CI 1.2-4.9) were independent predictors of death. In conclusion, NODAT developing early after renal transplantation was associated with poor long-term patient survival. Insulin indices calculated pretransplantation using HOMA and McAuley's Index did not predict NODAT.

Clinical and metabolic effects of first-line treatment with somatostatin analogues or surgery in acromegaly: a retrospective and comparative study

To evaluate the metabolic effects of first-line somatostatin analogues or surgery in acromegaly. Retrospective, comparative, 12-month follow-up. Two hundred and thirty one patients (123 men, age 47.32 ± 14.63 years) with active acromegaly, first line treatments were somatostatin analogues in 151 (65.4%) and surgery in 80 (34.6%). Metabolic syndrome (MS) parameters, glucose, insulin and GH during oral glucose tolerance test, stimulated insulin sensitivity by insulin sensitivity index (ISI Matsuda), early and total insulin-secretion rate by insulinogenic index and AUC(INS), visceral adiposity function, expressed by visceral adipose index (VAI). Somatostatin analogues treatment improved all MS parameters and significantly reduced fasting glucose (P < 0.001), HbA1c (P = 0.014) and the prevalence of DM (P = 0.003) when disease control was achieved. Both somatostatin analogues and surgery improved ISI Matsuda (P < 0.001) and reduced AUC(INS) (P < 0.001) and VAI (P < 0.001 and P = 0.003, respectively). Only in controlled somatostatin analogues-treated patients a significant reduction in insulinogenic index (P = 0.010) was observed. ISI Matsuda showed a significant independent correlation with IGF-1 levels (β = -0.258; P = 0.001) and VAI score (β = -0.430; P < 0.001). VAI was independently correlated with IGF-1 (β = 0.183; P = 0.004). Both somatostatin analogues and surgery can safely be used as first-line therapy in acromegaly, without any untoward effects on glucose tolerance. The control of acromegaly is the main determinant of beneficial effects on general features of insulin sensitivity. VAI could represent an additional link between disease control and insulin sensitivity.

Skim milk, whey, and casein increase body weight and whey and casein increase the plasma C-peptide concentration in overweight adolescents

In adults, dietary protein seems to induce weight loss and dairy proteins may be insulinotropic. However, the effect of milk proteins in adolescents is unclear. The objective was to test whether milk and milk proteins reduce body weight, waist circumference, homeostatic model assessment, plasma insulin, and insulin secretion estimated as the plasma C-peptide concentration in overweight adolescents. Overweight adolescents (n = 203) aged 12-15 y with a BMI of 25.4 ± 2.3 kg/m(2) (mean ± SD) were randomized to 1 L/d of skim milk, whey, casein, or water for 12 wk. All milk drinks contained 35 g protein/L. Before randomization, a subgroup of adolescents (n = 32) was studied for 12 wk before the intervention began as a pretest control group. The effects of the milk-based test drinks were compared with baseline (wk 0), the water group, and the pretest control group. Diet and physical activity were registered. Outcomes were BMI-for-age Z-scores (BAZs), waist circumference, plasma insulin, homeostatic model assessment, and plasma C-peptide. We found no change in BAZ in the pretest control and water groups, whereas it was greater at 12 wk in the skim milk, whey, and casein groups compared with baseline and with the water and pretest control groups. The plasma C-peptide concentration increased from baseline to wk 12 in the whey and casein groups and increments were greater than in the pretest control (P < 0.02). There were no significant changes in plasma C-peptide in the skim milk or water group. These data suggest that high intakes of skim milk, whey, and casein increase BAZs in overweight adolescents and that whey and casein increase insulin secretion. Whether the effect on body weight is primary or secondary to the increased insulin secretion remains to be elucidated.

Association of chronic viral hepatitis B with insulin resistance

AIM: To investigate the relationship between chronic viral hepatitis B (CVHB) and insulin resistance (IR) in Korean adults.

METHODS: A total of 7880 adults (3851 men, 4029 women) who underwent a comprehensive medical examination were enrolled in this study. Subjects diagnosed with either diabetes mellitus, or any other disorder that could influence their insulin sensitivity, were rejected. Anthropometry, metabolic risk factors, hepatitis B surface antigen, hepatitis B surface antibody, hepatitis B core antibody, fasting plasma glucose and insulin were measured for all subjects. Homeostasis model assessment (HOMA), quantitative insulin check index (QUICKI), and Mf_fm index were used for determining insulin sensitivity. Each participant was categorized into a negative, recovery, or CVHB group. To compare variables between groups, a t-test and/or one-way analysis of variance were used. Partial correlation coefficients were computed to present the association between insulin resistance and other variables. Multiple logistic regression analysis was used to assess the independent association between CVHB and IR.

RESULTS: The mean age of men and women were 48.9 and 48.6 years, respectively. Subjects in the CVHB group had significantly higher waist circumference [(86.0 ± 7.7 cm vs 87.3 ± 7.8 cm, P = 0.004 in men), (78.3 ± 8.6 cm vs 80.5 ± 8.5 cm, P < 0.001 in women)], cystatin C [(0.96 ± 0.15 mg/dL vs 1.02 ± 0.22 mg/dL, P < 0.001 in men), (0.84 ± 0.15 mg/dL vs 0.90 ± 0.16 mg/dL, P < 0.001 in women)], fasting insulin [(5.47 ± 3.38 μU/mL vs 6.12 ± 4.62 μU/mL, P < 0.001 in men), (4.57 ± 2.82 μU/mL vs 5.06 ± 3.10 μU/mL, P < 0.001 in women)] and HOMA index [(1.24 ± 0.86 vs 1.43 ± 1.24, P < 0.001 in men), (1.02 ± 0.76 vs 1.13 ± 0.87, P = 0.033 in women)] compared to control group. The HOMA index revealed a positive correlation with body mass index (BMI) (r = 0.378, P < 0.001), waist circumference (r =0.356, P < 0.001), percent body fat (r = 0.296, P < 0.001), systolic blood pressure (r = 0.202, P < 0.001), total cholesterol (r = 0.134, P < 0.001), triglycerides (r = 0.292, P < 0.001), cystatin C (r = 0.069, P < 0.001) and uric acid (r = 0.142, P < 0.001). The QUICKI index revealed a negative correlation with BMI (r = -0.254, P < 0.001), waist circumference (r = 0-0.243, P < 0.001), percent body fat (r = -0.217, P < 0.001), systolic blood pressure (r = -0.132, P < 0.001), total cholesterol (r = -0.106, P < 0.001), triglycerides (r = -0.205, P < 0.001), cystatin C (r = -0.044, P < 0.001) and uric acid (r = -0.096, P < 0.001). For subjects identified with IR, the odds ratio of an accompanying diagnosis of chronic hepatitis B was 1.534 (95% CI: 1.158-2.031, HOMA index criteria) or 1.566 (95% CI: 1.124-2.182, QUICKI criteria) after adjustment for age, gender, BMI, and amount of alcohol consumption.

CONCLUSION: Our study demonstrates that CVHB is associated with IR. CVHB may need to be monitored for occurrence of IR and diabetes mellitus.

Association of vitamin D with glucose levels in indigenous and mixed population Argentinean boys

INTRODUCTION

There is little information about low vitamin D concentrations in apparently healthy indigenous children in South America.

OBJECTIVES

(a) To compare the prevalence of hypovitaminosis D in SAC (San Antonio de los Cobres) versus BA (Buenos Aires) boys and (b) to determine the association of serum vitamin D concentration with age, gender, and risk factors for diabetes.

METHODS

This cross-sectional study compares 129 boys from SAC with a 98% indigenous population, versus 116 boys from BA with a mixed population. Anthropometric measures and serum levels of glucose, lipids, insulin, and 25-hydroxyvitamin D [25(OH)D] were measured in May 2011 and May 2010 (fall season). Optimal, insufficiency, deficiency, and severe deficiency of vitamin D were defined as [25(OH)D[levels ≥75 nmol/L, 50 to <75 nmol/L, 25 to <50 nmol/L, and <25 nmol/L respectively.

RESULTS

The mean age was 9.7±2.7 in SAC and 11.3±2.51 years in BA children. Seventeen (13.2%) SAC and 2 (1.7%) BA children were underweight; 99 (76.7%) SAC and 58 (50.0%) BA children were normal weight; 5 (3.9%) SAC and 15 (12.9%) BA children were overweight; and 8 (6.2%) SAC and 41 (35.3%) BA children were obese (p<0.001). Sixty-six (51.2%) SAC and 1 (0.9%) BA children had vitamin D severe deficiency; 58 (45.0%) SAC and 53 (45.7%) BA children had deficiency; 5 (3.9%) SAC and 61 (52.6%) BA had insufficiency; and 0 (0%) SAC and 1 (0.9%) BA children had optimal vitamin D (p<0.001). Therefore, there was a lower prevalence of overweight/obesity and a higher prevalence of vitamin D deficiency in SAC than in BA children. Separate linear regression models showed an inverse association between glucose levels (beta=-0.22; p=0.01) and HOMA=IR (beta=-0.21; p=0.02) with vitamin D levels adjusted for age, z-BMI and community.

CONCLUSIONS

There was a higher prevalence of 25(OH)D deficiency in SAC versus BA boys, suggesting that dark skin, high altitudes, or genetic backgrounds could contribute to this problem. In addition, we found an inverse association between [25(OH)D] and glucose concentration in apparently healthy children. Additional longitudinal studies should be done to confirm these findings.

Associations between surrogate measures of insulin resistance and waist circumference, cardiovascular risk and the metabolic syndrome across Hispanic and non-Hispanic white populations

AIMS

We evaluated the relations between surrogate indices of insulin resistance and waist circumference, metabolic syndrome and coronary heart disease risk across Hispanic and non-Hispanic white populations.

METHODS

The study was a cross-sectional analysis of participants without diabetes in the San Antonio Heart Study, Mexico City Diabetes Study and Spanish Insulin Resistance Study. We evaluated commonly used indices of insulin resistance, including homeostasis model assessment, McAuley's index, Gutt's insulin sensitivity index, Avignon's insulin sensitivity index and the Stumvoll index with and without demographics, the modified Matsuda index and the product of the triglycerides and glucose index. The metabolic syndrome was defined by American Heart Association/National Heart, Lung, and Blood Institute criteria and coronary heart disease risk by Framingham risk scores.

RESULTS

The Stumvoll index with demographics and the Avignon's insulin sensitivity index had the strongest correlations with waist circumference across populations. The triglycerides and glucose and McAuley's indices had the most robust correlations with Framingham risk score. The triglycerides and glucose index had the greatest ability to detect individuals with the metabolic syndrome and ≥ 10% coronary heart disease risk. Some indices display significant variability in the strength of the relationship with adiposity and coronary heart disease risk across populations.

CONCLUSIONS

There are significant differences between insulin resistance indices regarding the ability to detect the metabolic syndrome and coronary heart disease risk across populations. Studies may need to consider the index of insulin resistance that best suits the objectives.

Shiftwork and higher pancreatic secretion: early detection of an intermediate state of insulin resistance?

Previous studies have suggested that shiftwork can affect the prevalence of metabolic syndrome. This is thought to be related to disturbance of lipid parameters rather than their effects on glucose metabolism. Several complex mechanisms are suspected to be involved and notably insulin resistance, though the available data are limited. The objective of the present study was to provide further evidence for the effects of shiftwork on glucose and lipid metabolism with a specific focus on insulin resistance. A cross-sectional study has recruited 97 shiftworkers (SWs) (three shifts, 8 h) and 95 strictly day workers (DWs) from the same plant for 2001-2002. Several indices of insulin sensitivity or resistance were calculated, based on formulas of the homeostasis model assessment for insulin resistance (HOMA-IR), the Revised-Quicki, McAuley and Disse indices. The HOMA-β-cell index was used as a reflection of pancreatic secretion. Characteristics of the occupation, habitual diet and lifestyles were recorded. Logistic regression analysis in which pancreatic function or insulin sensitivity was the dependent variable was used to compare alternative models.

RESULTS

SWs were characterized as having significantly higher triglycerides and free fatty acids and normal but lower blood glucose. The risk of a high β-cell activity was increased almost three-fold in SWs. By adjusting for many confounding factors, SWs had significantly lower insulin sensitivity according to several indices, whereas HOMA-IR was not meaningfully different between shift and DWs. Lower insulin sensitivity and a compensatory pancreas response to maintain a normal glucose tolerance may suggest an intermediate state before development of frank insulin resistance in SWs. Early detection of these moderate alterations of the insulin/glucose balance could be important in the prevention of diabetes.

Physical activity is related to insulin sensitivity in children and adolescents, independent of adiposity: a review of the literature

In adults, there is evidence that physical activity effectively improves insulin sensitivity regardless of adiposity. Whether this is also the case in children and adolescents is less clear. Clarifying this matter may help to identify the best outcomes to target in exercise programs for these age groups, where changes in adiposity may not always be desirable or realistic. A review of the literature was conducted on studies that examined the relationships of physical activity, cardiorespiratory fitness and strength with insulin sensitivity independent of adiposity in children and adolescents. Experimental (intervention) and correlational (longitudinal and cross-sectional) studies on participants ages 18 years and younger were identified. A total of 42 studies were included in this review. Sample sizes in the studies ranged from 14 to 4955 participants, with individual ages ranging from 5 to 19 years. A significant relationship with insulin sensitivity existed in 78% of studies on physical activity, 69% of studies on cardiorespiratory fitness and 66% of studies on strength. In studies that examined both physical activity and cardiorespiratory fitness concurrently, evidence suggests that they are both correlated with insulin sensitivity independent of adiposity, especially when physical activity is at higher intensities. However, the strength of this relationship might be influenced by study design, measurement techniques and participant characteristics. This is the first review of its type to take research design into account and to examine study outcomes according to participant ethnicity, gender, age, pubertal status and weight status.

Evaluation of two new surrogate indices including parameters not using insulin to assess insulin sensitivity/resistance in non-diabetic postmenopausal women: a MONET group study

AIM

The study evaluated and compared, with other surrogate indices of insulin sensitivity/resistance (IS/R), the relevance of the TyG index, a product of fasting glucose and triglyceride (TG) levels, and the EGIR index, which includes TG, high-density lipoprotein cholesterol (HDL-c) and waist circumference in its formula to estimate IS/R, in non-diabetic postmenopausal women.

METHODS

A secondary analysis was performed using the baseline data for 163 non-diabetic postmenopausal women from the Montreal-Ottawa New Emerging Team (MONET) population database. The subjects participated in hyperinsulinaemic-euglycaemic (HIEG) clamp and oral glucose tolerance (OGTT) tests. Correlations and comparisons between surrogate indices were performed in addition to inter-rater agreement tests. The optimal value of surrogate indices for diagnosis of IS/R was established on a receiver operating characteristic (ROC) scatter plot.

RESULTS

A significant correlation was found between the HIEG clamp and all IS/R surrogate indices tested [r=-0.370 (TyG index) to 0.608 (SIisOGTT index); P<0.001]. On ROC curve analysis, a higher AUROC was found for SIisOGTT (0.791) than for TyG and EGIR (0.706 and 0.675, respectively; P=0.07 and P<0.05, respectively).

CONCLUSION

The TyG and EGIR IS/R indices were only relatively modestly related to the HIEG clamp. In contrast, both fasting- and OGTT-derived IS/R surrogate indices, which include insulin values in their formulae, appeared to be more accurate in estimating IS/R in our study population. Thus, the TyG and EGIR IS/R indices need to be tested and validated more extensively in different populations before being put to large-scale clinical use.

Early basal insulin therapy decreases new-onset diabetes after renal transplantation

No effective interventions to reduce risk for new-onset diabetes after transplantation (NODAT), a condition associated with postoperative hyperglycemia and reduced patient and graft survival, have been established. In this 1-year, proof-of-concept clinical trial, we randomly assigned 50 renal transplant recipients to immediate-postoperative isophane insulin for evening blood glucose ≥140 mg/dl (treatment group) or short-acting insulin and/or oral antidiabetic agents for blood glucose ≥180-250 mg/dl (standard-of-care control group). We included only patients without a history of diabetes who received tacrolimus. By the third postoperative evening, all patients in the treatment group had blood glucose ≥140 mg/dl and were subsequently treated with basal insulin; during the first 3 weeks after transplantation, the mean ± SD daily insulin dosage was 17±11 IU/d. Among controls, 23 (92%) of 25 had blood glucose ≥200 mg/dl and 18 (72%) of 25 received standard-of-care antihyperglycemic treatment. Asymptomatic hypoglycemia occurred five times in the treatment group and once in the control group. Throughout follow-up, the treatment group had 73% lower odds of NODAT (odds ratio, 0.27) than the control group, and hemoglobin A1c was on average 0.38% lower in the treatment group than the control group. Twelve months after transplantation, all patients in the treatment group were insulin-independent, whereas 7 (28%) of 25 controls required antidiabetic agents. The groups did not differ for insulin sensitivity, but the treatment group showed better β-cell function throughout the 1-year follow-up. In conclusion, this study suggests regimens that include basal insulin significantly reduce the odds for NODAT after renal transplantation, presumably via insulin-mediated protection of β cells.

Prevalence of hyperinsulinemia associated with body mass index, genetic predisposition, and lifestyle in college freshmen students

OBJECTIVE

College lifestyle places an individual at greater risk for the development of insulin resistance (IR) and disease. The aim of this study was to establish a baseline measurement of insulin, and other variables influencing IR in college freshmen.

PARTICIPANTS

Twenty-two men and women, 18 to 19 years of age, during first month of college.

METHODS

Following 12-hour fast, subjects reported to the laboratory for determination of body mass index (BMI) and completion of questionnaire determining ethnicity, family history, and patterns of diet, exercise, and stress. Blood samples were obtained and analyzed for glucose and insulin.

RESULTS

Mean insulin value for men (14.9 ± 1.86 μU/mL) was normal, and that for women (17.3 ± 1.74 μU/mL) was slightly elevated. When subjects were grouped by BMI, genetic predisposition, and summated lifestyle risk, fasting insulin values were significantly different. Eight of 22 subjects were hyperinsulinemic (insulin >19 μU/mL).

CONCLUSION

Hyperinsulinemia is prevalent in this population and merits further investigation and intervention.

Evaluation of various insulin sensitivity indices in lean idiopathic hirsutism patients

Hirsutism is characterized by excessive growth of terminal hair in a male pattern. Idiopathic hirsutism (IH) is a common cause of hirsutism. Since there are few data demonstrating IH is associated with insulin resistance, we tried to assess various insulin sensitivity indices in lean IH and compare with healthy subjects. A cross-sectional study was performed in 71 lean (BMI between 20-25 kg/m(2)) women (17-39 years old), 31 with IH and 40 healthy individuals. Blood glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), hepatic insulin sensitivity (ISI (HOMA)), Quicky index, reciprocal fasting insulin resistance index, fasting Belfiore index, and fasting glucose/insulin ration (GIR) were estimated using a single fasting sample of glucose and insulin levels. Raynaud indices calculated using the mathematical estimation in a single fasting sample of insulin levels were determined and compared in two groups. Fasting insulin, Raynaud index, HOMA-IR and Fasting insulin resistance index (FIRI) results were higher in IH group than in controls (p<0.01, for all). Fasting Belfiore index, QUICKI index, ISI(HOMA) and FIRI(-1) results were lower in IH group than in controls (p<0.01, for all). Our study showed that lean IH patients were more insulin resistant than healthy subjects. We propose that insulin sensitivity indices are useful methods for measuring insulin resistance in IH.

Prediction of insulin resistance with anthropometric measures: lessons from a large adolescent population

OBJECTIVE

The aim of this study was to describe the minimum number of anthropometric measures that will optimally predict insulin resistance (IR) and to characterize the utility of these measures among obese and nonobese adolescents.

RESEARCH DESIGN AND METHODS

SIX ANTHROPOMETRIC MEASURES (SELECTED FROM THREE CATEGORIES: central adiposity, weight, and body composition) were measured from 1298 adolescents attending two New York City public high schools. Body composition was determined by bioelectric impedance analysis (BIA). The homeostatic model assessment of IR (HOMA-IR), based on fasting glucose and insulin concentrations, was used to estimate IR. Stepwise linear regression analyses were performed to predict HOMA-IR based on the six selected measures, while controlling for age.

RESULTS

The stepwise regression retained both waist circumference (WC) and percentage of body fat (BF%). Notably, BMI was not retained. WC was a stronger predictor of HOMA-IR than BMI was. A regression model using solely WC performed best among the obese II group, while a model using solely BF% performed best among the lean group. Receiver operator characteristic curves showed the WC and BF% model to be more sensitive in detecting IR than BMI, but with less specificity.

CONCLUSION

WC combined with BF% was the best predictor of HOMA-IR. This finding can be attributed partly to the ability of BF% to model HOMA-IR among leaner participants and to the ability of WC to model HOMA-IR among participants who are more obese. BMI was comparatively weak in predicting IR, suggesting that assessments that are more comprehensive and include body composition analysis could increase detection of IR during adolescence, especially among those who are lean, yet insulin-resistant.

No effect of ultraviolet radiation on blood pressure and other cardiovascular risk factors

OBJECTIVES

Recent epidemiological studies have reported inverse associations between vitamin D status and blood pressure. The study aim is to determine if exposure to ultraviolet B radiation, which synthesizes vitamin D, lowers blood pressure, compared with ultraviolet A radiation.

METHODS

Men and women (n = 119) with low vitamin D levels [serum 25-hydroxyvitamin D [25(OH)D] <50 nmol/l], completed a randomized clinical trial carried out during winter. Blood pressure was measured for 12-14 h with an ambulatory monitor at baseline and 12 weeks. In between, participants received 24 whole body exposures of either ultraviolet B (n = 58) or ultraviolet A (n = 61) over 12 weeks.

RESULTS

Mean (SD) 25(OH)D increased from 43.7 (9.7) to 92.6 (16.9) nmol/l in the ultraviolet B arm after 12 weeks, and from 45.4 (9.2) to 64.9 (11.3) nmol/l in the ultraviolet A arm. However, mean blood pressure, which was similar for the ultraviolet B and ultraviolet A at baseline (134.9/79.2 vs. 132.9/77.8 mmHg; P = 0.59 and 0.56, respectively), did not change from baseline to 12 weeks in either group. The mean change [95% confidence interval (CI)] in blood pressure over this period in the ultraviolet B group compared with the ultraviolet A group was -2.2 (-7.8, 3.3) mmHg for systolic (P = 0.42) and -2.7 (-6.5, 1.0) mmHg for diastolic (P = 0.15).

CONCLUSION

Exposure to ultraviolet B did not lower blood pressure. Our results suggest that if vitamin D protects against cardiovascular disease, it involves some mechanism other than blood pressure.

The effects of rosiglitazone and metformin on inflammation and endothelial dysfunction in patients with type 2 diabetes mellitus

Diabetic patients have a markedly increased risk of cardiovascular disease compared with non-diabetics. Two drug groups today target insulin resistance; biguanides and thiazolidinediones. In addition, these may have other effects on cardiovascular risk factors. The aim of this study was to evaluate the effects of metformin and rosiglitazone on non-traditional cardiovascular risk factors. Forty type 2 diabetic patients were randomized into metformin and rosiglitazone groups. After receiving the optimal doses, the patients were monitored for 12 weeks. Biochemical parameters, lipid parameters, CRP, insulin, c-peptide, and HbA1c levels were analyzed. VWF, PAI-1, ICAM-1, TNF-α, IL-6, E-selectin, and fibrinogen levels were measured in order to assess coagulation status and endothelial dysfunction. In the metformin group, body mass index, PPG, HbA1c, IL-6, ICAM-1, and TNF-α levels were significantly decreased after 12 weeks compared with the basal levels. IL-6 levels decreased from 75 pg/ml ± 20 to 42 pg/ml ± 9 (P 0.023) and TNF- α levels from 61 pg/ml ± 31 to 39 pg/ml ± 10 (P 0.018). In the rosiglitazone group, FPG, PPG, HbA1c, insulin, HOMA-IR, IL-6, and TNF-α levels decreased significantly after 12 weeks compared with the basal levels. IL-6 levels decreased from 78 pg/ml ± 21 to 41 pg/ml ± 9 (P 0.028) and TNF-α levels from 62 pg/ml ± 19 to 37 pg/ml ± 10 (P 0.012). At the end of the study, no significant differences were determined between groups. Insulin resistance and type 2 diabetes are strongly associated with low grade inflammation. Both metformin and rosiglitazone were effective in controlling inflammatory markers in addition to metabolic parameters.

The dynamic insulin sensitivity and secretion test--a novel measure of insulin sensitivity

The objective was to validate the methodology for the dynamic insulin sensitivity and secretion test (DISST) and to demonstrate its potential in clinical and research settings. One hundred twenty-three men and women had routine clinical and biochemical measurements, an oral glucose tolerance test, and a DISST. For the DISST, participants were cannulated for blood sampling and bolus administration. Blood samples were drawn at t = 0, 10, 15, 25, and 35 minutes for measurement of glucose, insulin, and C-peptide. A 10-g bolus of intravenous glucose at t = 5 minutes and 1 U of intravenous insulin immediately after the t = 15 minute sample were given. Fifty participants also had a hyperinsulinemic-euglycemic clamp. Relationships between DISST insulin sensitivity (SI) and the clamp, and both DISST SI and secretion and other metabolic variables were measured. A Bland-Altman plot showed little bias in the comparison of DISST with the clamp, with DISST underestimating the glucose clamp by 0.1·10(-2)·mg·L·kg(-1)·min(-1)·pmol(-1) (90% confidence interval, -0.2 to 0). The correlation between SI as measured by DISST and the clamp was 0.82; the c unit for the receiver operating characteristic curve analysis for the 2 tests was 0.96. Metabolic variables showed significant correlations with DISST SI and the second phase of insulin release. The DISST also appears able to distinguish different insulin secretion patterns in individuals with identical SI values. The DISST is a simple, dynamic test that compares favorably with the clamp in assessing SI and allows simultaneous assessment of insulin secretion. The DISST has the potential to provide even more information about the pathophysiology of diabetes than more complicated tests.

Fasting glucose to leptin ratio as a new diagnostic marker in patients with diabetes mellitus

OBJECTIVES

To identify the fasting glucose/leptin ratio as a new simple method for the detection of insulin resistance in Iraqi diabetes mellitus patients, and to examine its usefulness as a new marker for insulin resistance.

METHODS

A case control study conducted at the National Diabetes Center, College of Medicine at Al-Mustansiryia University from 1 August 2008 to 30 January 2010. An enzyme spectrophotometric method was used to determine fasting glucose, while HPLC Technique determined leptin and insulin hormones in serum of patients with diabetes mellitus (n=61) and normal healthy subjects as controls (n=63).

RESULTS

A positive significant correlation with linear regression equations were found between fasting insulin and fasting leptin hormones, and fasting glucose/insulin and fasting glucose/leptin ratios among the diabetic patient group. While negative, significant correlations were found with linear regression equations between fasting insulin and fasting glucose/insulin ratio, and fasting insulin and fasting glucose/leptin ratio in patients group. Glucopse/leptin ratio had a higher sensitivity compared to glucose/insulin ratio, Quantitative Insulin-Sensitivity Check Index and Homeostasis Model Assessment indexes.

CONCLUSION

Overall, the glucose/leptin ratio can be used in addition to glucose/insulin ratio, Quantitative Insulin-Sensitivity Check Index, and Homeostasis Model Assessment to accurately assess insulin resistance in subjects with hyperglycemia.

Community screening for cardiovascular risk factors and levels of treatment in a rural Māori cohort

OBJECTIVES

To document levels of cardiovascular disease (CVD), diagnosed and undiagnosed risk factors and clinical management of CVD risk in rural Māori.

METHODS

Participants (aged 20-64 years), of Māori descent and self-report, were randomly sampled to be representative of age and gender profiles of the community. Screening clinics included health questionnaires, fasting blood samples, blood pressure and anthropometric measures. Data were obtained from participants' primary care physicians regarding prior diagnoses and current clinical management. New Zealand Cardiovascular Guidelines were used to identify new diagnoses at screening and Bestpractice electronic-decision support software used to estimate 5-year CVD risk.

RESULTS

Mean age of participants (n=252) was 45.7 ± 0.7, 8% reported a history of cardiac disease, 43% were current smokers, 22% had a healthy BMI, 30% were overweight and 48% obese. Hypertension was previously diagnosed in 25%; an additional 22% were hypertensive at screening. Dyslipidaemia was previously diagnosed in 14% and an additional 43% were dyslipidaemic at screening. Type-2 diabetes was previously diagnosed in 11%. Glycaemic control was achieved in only 21% of those with type-2 diabetes. Blood pressure and cholesterol were above recommended targets in more than half of those with diagnosed CVD risk factors.

CONCLUSIONS

High levels of diagnosed and undiagnosed CVD risk factors, especially hypertension, dyslipidaemia and diabetes were identified in this rural Māori community.

IMPLICATIONS

There is a need for opportunistic screening and intensified management of CVD risk factors in this indigenous population group.

Comparison of insulin sensitivity indices properties calculated from OGTT

The aim of this study was to present the properties of insulin sensitivity indices formulas to justify selection of formulas to evaluate of insulin sensitivity for calculation from an oral glucose tolerance test (OGTT) data. Twelve of the most applicable formulae for ISI calculation were analyzed in the view of two sets of results: 1) point contrasts, calculated as the ratio of average ISI values in lean and obese groups of patients; and 2) interval contrasts, calculated as ratios of T from the two-sided t-test, evaluated as dimensionless, mutually comparable contrasts within a continuous scale. Statistical significance of individual ISIs in terms of their contrasts was evaluated by two-sided t-tests. P<0.001 was a considered statistically significance between a group of 59 healthy volunteers with BMI<25 kg/m2 and a group of 63 volunteers with BMI≥25 kg/m2 who underwent frequent OGTT sampling. To compare data of an individual subject with the standard, we recommend selecting the formulas with a high point contrast. To compare of data of several subject groups, we recommend using the formulas with a high interval contrast.

Bioactive properties and clinical safety of a novel milk protein peptide

Background

Milk protein fractions and peptides have been shown to have bioactive properties. This preliminary study examined the potential mechanisms of action and clinical safety of novel milk protein peptide (MP).

Findings

A novel MP mixture inhibits the tyrosine kinase activity of epidermal growth factor receptor (EGFR), vascular endothelial growth factor receptor 2 (VEGFR2), and insulin receptor (IR) with IC₅₀ of 9.85 μM, 7.7 μM, and 6.18 μM respectively. In vitro, this multi-kinase inhibitor causes apoptosis in HT-29 colon cancer cells, and in a C. elegans worm study, showed a weak but significant increase in lifespan. A six week double-blind, placebo-controlled study involving 73 healthy volunteers demonstrated that the MP mixture is safe to consume orally. All clinical blood markers remained within normal levels and no clinically significant side effects were reported. There was some evidence of improved insulin sensitivity, neutrophil-to-lymphocyte ratio (NLR), and quality of life assessment of role of physical function.

Conclusions

These data in combination with the observed in vitro anti-cancer properties warrant further clinical studies to investigate this MP mixture as a potential clinical nutrition intervention for improving the quality of life and clinical outcomes in cancer patients.

Trial Registration

NCT01412658

Polymorphism of peroxisome proliferator-activated receptor γ (PPARγ) Pro12Ala in the Iranian population: relation with insulin resistance and response to treatment with pioglitazone in type 2 diabetes

The peroxisome proliferator-activated receptor γ (PPARγ) has important effects on insulin sensitivity, obesity and diabetes. Pioglitazone improves insulin sensitivity by activating PPARγ. In view of inter-individual variability in therapeutic response to pioglitazone, this study was designed to search for an association between type 2 diabetes mellitus and Pro12Ala single-nucleotide polymorphism (SNP) in PPARγ (SNP rs1801282) and to investigate whether these genetic variants affect pioglitazone response in an Iranian population. A total of 101 patients with type 2 diabetes were treated for 12 weeks with pioglitazone (15 mg/day). Paraclinical parameters were measured before and after therapy. We genotyped 128 control participants without diabetes and all patients with type 2 diabetes. The Pro12Ala polymorphism in PPARγ was detected with real-time PCR. The Ala allele was found in 7% of the control participants vs. 3% of those with type 2 diabetes (P=0.04). The genotypic frequencies of Pro/Ala were 14.06% in the former group vs. 5.94% in the latter (P=0.036). There were significant changes in some laboratory values and biochemical markers of insulin sensitivity after pioglitazone therapy. The Pro12Ala polymorphism was associated with significant changes in insulin-to-glucose ratio after treatment (P=0.015 and P=0.005). Our findings suggest that in carriers of the 12Ala variant, pioglitazone significantly reduced the risk of type 2 diabetes, and in diabetic patients with the Pro12Ala genotype, the therapeutic response to treatment was better than in patients with the Pro12Pro genotype, although the difference between groups did not reach statistical significance.

Correlation between measures of insulin resistance in fasting and non-fasting blood

BACKGROUND

Epidemiological investigation of insulin resistance is difficult. Standard measures of insulin resistance require invasive investigations, which are impractical for large-scale studies. Surrogate measures using fasting blood samples have been developed, but even these are difficult to obtain in population-based studies. Measures of insulin resistance have not been validated in non-fasting blood samples. Our objective was to assess the correlations between fasting and non-fasting measures of insulin resistance/sensitivity.

METHODS

Fasting and non-fasting measurements of metabolic function were compared in 30 volunteers (15 male) aged 28 to 48 years. Participants provided a morning blood sample after an overnight fast and a second sample approximately 4 hours after lunch on the same day.

RESULTS

Non-fasting levels of the adipokines leptin, adiponectin, and leptin:adiponectin ratios were not significantly different and highly correlated with fasting values (r values 0.95, 0.96, and 0.95 respectively, P values < 0.001). There were moderate correlations between fasting and non-fasting estimates of insulin sensitivity using the McAuley (r = 0.60, P = 0.001) and QUICKI formulae (r = 0.39, P = 0.037). The HOMA-IR estimate of insulin resistance was also moderately correlated (r = 0.45, P = 0.016).

CONCLUSIONS

Semi-fasting measures of leptin, adiponectin, and leptin:adiponectin ratios correlate closely with fasting values and are likely to be sufficient for population-based research. Other measures of insulin resistance or sensitivity in semi-fasted blood samples are moderately correlated with values obtained after an overnight fast. These estimates of insulin resistance/sensitivity may also be adequate for many epidemiological studies and would avoid the difficulties of obtaining fasting blood samples.

Low estradiol-to-testosterone ratio is associated with oligo-anovulatory cycles and atherogenic lipidic pattern in women with polycystic ovary syndrome

OBJECTIVE

The estradiol-to-testosterone (E2/T) ratio has been investigated in different diseases but few in vivo data are available with regard to its role in women with ovary syndrome (PCOS). The aim of this study was to evaluate the role of the E2/T ratio in the ovulatory function and metabolic pattern in such women.

METHODS

We retrospectively evaluated hyperandrogenemia, clinical hyperandrogenism, ovarian morphology, hypothalamo-hypophyseal axis and metabolic syndrome parameters in a cohort of 202 consecutive women affected by PCOS. An oral glucose tolerance test measured areas under the curve for insulin (AUC(2hIRI)), for glucose (AUC(2hglucose)), and the HOMA-IR and Matsuda index of insulin resistance were evaluated. Serum progesterone (Pg) was determined from day 20 to day 24 of the menstrual cycle and chronic oligo-anovulation was established if two consecutive cycles were anovulatory.

RESULTS

Women with PCOS with normal ovulation [66/202 (32.7%)] showed a significantly higher E2/T ratio than women with PCOS with chronic oligo/anovulation [136/202 (67.3%)] (p < 0.05). Using a series of multiple linear regression models, we also investigated which variables correlated with the E2/T ratio. The analysis showed a strongly positive correlation of the E2/T ratio with Pg (β =  0.473, p < 0.001) and a negative correlation with total cholesterol (β =  -0.433, p < 0.001).

CONCLUSIONS

Our data suggest that in women with PCOS a low E2/T ratio is not only associated with chronic oligo-anovulation, but is also a determinant factor of the atherogenic lipid profile.

Androgenetic alopecia and insulin resistance: are they truly associated?

BACKGROUND

Controversies exist regarding the association of androgenetic alopecia (AGA) with insulin resistance. Are they truly associated, or is insulin resistance just related to aging, obesity, or to the presence of metabolic syndrome?

OBJECTIVE

To assess insulin resistance in young nonobese patients with AGA with and without metabolic syndrome.

METHODS

The study included four equally distributed groups of age-, sex-, and body mass index-matched young, nonobese subjects: 30 patients with AGA and metabolic syndrome (group 1); 30 patients with AGA and no metabolic syndrome (group 2); 30 patients with metabolic syndrome and no AGA (group 3); and 30 healthy controls (group 4). Insulin resistance based on fasting insulin levels and homeostasis model assessment of insulin resistance (HOMA-IR) was assessed in all groups.

RESULTS

Twenty-three patients in group 1, four patients in group 2, 25 patients in group 3, and three healthy controls had insulin resistance with statistically significant differences in fasting insulin and HOMA-IR levels between all groups, between groups 1 and 2, groups 1 and 4, groups 2 and 3, and groups 3 and 4. No significant differences existed between groups 2 and 4 or groups 1 and 3. Correlations between insulin resistance parameters, age of patients, disease duration, and stages of AGA in males and females revealed nonsignificant differences.

CONCLUSIONS

Patients with metabolic syndrome, with or without AGA, were significantly more insulin resistant compared with patients with AGA with no metabolic syndrome and with healthy subjects and, therefore, no true association exists between AGA and insulin resistance.

Correlation between changes of blood pressure with insulin resistance in type 2 diabetes mellitus with 4 weeks of pioglitazone therapy

OBJECTIVE:

To examine effects of pioglitazone (PIO) on systolic, diastolic, pulse and mean blood pressures (SBP, DBP, PP and MP, respectively) in type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS:

One hundred and six normotensive patients with T2DM with mean fasting blood glucose (FBS; 183 ± 6 mg/dl) were randomly divided into two groups. Test group was treated with 15 mg of PIO in addition to metformin 500 mg three times per day in both groups. SBP, DBP, PP and MP and fasting insulin, FBS and lipid profiles were measured before and after PIO therapy.

RESULTS:

There was a significant reduction in SBP (123 ± 2 vs. 118 ± 2 mmHg, P < 0.05), PP (41 ± 1 vs. 37 ± 1 mmHg, P < 0.05), and MP (95 ± 1 vs. 91 ± 1, P < 0.05). Clinical reduction in DBP was observed but not significant (82 ± 2 vs. 81 ± 1 mmHg, P > 0.05). There was a significant correlation between decline in SBP and DBP with respective baseline values (r = 0.76, P < 0.001 and r = 0.62, P < 0.001, respectively). Changes in PP and MP strongly correlated with baseline values (r = 0.51, P < 0.05 and r = 0.56, P < 0.05, respectively). There was a parallel reduction of FBS (183 ± 2 vs. 121 ± 3, P < 0.001) but reduction in IR or lipid profiles was not significant in test group. Changes in BP were not significant in control group ( P > 0.05).

CONCLUSION:

PIO treatment of T2DM showed early reduction of SBP and MP within first 4 weeks. Results suggest that pharmacodynamic effects of PIO mainly affect the systolic component. We hereby suggest that reduction of BP by PIO is independent from mechanisms of changes in IR and dyslipidaemia in normotensive diabetic patients.

Comparison of McAuley/fasting insulin indices with ATP III clinical criteria for the diagnosis of insulin resistance in type 2 diabetes mellitus

OBJECTIVE

To estimate the prevalence of insulin resistant syndrome (IRS) among newly diagnosed patients with type 2 diabetes and to test their validity against two indices of insulin resistance (IR).

MATERIALS AND METHODS

Prevalence of IRS was estimated according to the criteria used by ATP III in newly diagnosed type 2 diabetic patients. Sensitivity and specificity of the ACE criteria were calculated against two indices of IR namely fasting insulin (FI) level > 12 mU/l and McAuley index (McA) < 5.8. [McA= exp [2.63--0.28 ln(insulin in mU/l) -- 0.31 ln(triglycerides in mmol/l)].

RESULTS

35.7% of patients had IRS by ATP III criteria. 64.3% of patients were insulin resistant by FI and McA in each index. In patients who had IRS with ATP criteria, 80% and 86.6% were found to have McA and FI in the insulin resistant range. Out of the patients who were resistant by McA, only 40.6% had IR by ACE criteria and 93% had shown IR by FI. Out of all patients who did not fulfill the ATP III for IR, 74% and 59% were detected as having IR by fasting insulin and McA respectively. Sensitivity of the ACE criteria when tested against the FI and McA were 37.5% and 40.6%, specificity were 70% and 80%, respectively.

CONCLUSIONS

IRS was common among the newly diagnosed patients with type 2 diabetes. ACE criteria showed an acceptable specificity but lack adequate sensitivity when compared with the two Indices of insulin resistance. More valid and clinically useful criteria should be available for the accurate diagnosis of IRS in clinical practice.

Vitamin D and parathyroid hormone in insulin resistance of abdominal obesity: cause or effect?

The objective was to examine whether there were causal links between vitamin D status, parathyroid hormone, insulin resistance (IR)/insulin sensitivity (IS) and the metabolic syndrome (MS). A total of 72 Caucasian men and women, aged 55.7 ± 7.57 years, with body mass index 33.4 ± 4.02  kg/m(2) and abdominal obesity, were assessed for IR/IS based on three commonly used indices before and after 12 weeks of supervised weight loss. During weight stability, though both lower intact parathyroid hormone (iPTH) and higher vitamin D were independently associated with greater IS/lower IR, this was consistent for iPTH across the surrogate measures tested. Higher iPTH, but not lower vitamin D, increased the risk of MS after adjustment for IR/IS. Weight loss resulted in significant reductions in percent fat (-2.83 ± 2.20%), waist (-9.26 ± 5.11  cm), improvements in all IS indices, reductions in MS and iPTH (-0.28 ± 1.17  pmol/l), but no increase in vitamin D (+2.19 ± 12.17  nmol/l). Following weight loss, ΔiPTH either predicted change in IR/IS or contributed to their variance by 4.1-8.9%. On adjustment for IR/IS, higher ΔiPTH did not significantly predict MS after weight loss, though the odds ratios for the effect were sizeable. The data are suggestive of an intrinsic inverse relationship between iPTH and IS in abdominally obese individuals, independent of vitamin D. There remains the possibility of a direct relationship between iPTH and MS.

Assessing impaired glucose tolerance and insulin resistance in polycystic ovarian syndrome with a muffin test: an alternative to the glucose tolerance test

OBJECTIVE

To determine the sensitivity of a high-glucose load in a meal as an alternative to the standard oral glucose tolerance test (OGTT) in detecting impaired glucose tolerance and insulin resistance in women with polycystic ovarian syndrome (PCOS) and the relationship of body composition to insulin resistance in the PCOS cohort.

METHODS

In this prospective, single-center study, women with PCOS who were being followed up as out-patients were recruited. The study was performed between November 2007 and March 2008. All participants underwent OGTT before study enrollment. Participants were given a meal including carbohydrates, fat, and protein. Glucose and insulin levels were measured every 30 minutes for 2 hours after completing the meal. Body composition was measured by dual-energy x-ray absorptiometry.

RESULTS

Thirteen of the 15 participants completed the meal tolerance test and the body composition study. Four of 13 participants (31%) had abnormal glucose tolerance with the meal test compared with 2 of 8 participants (25%) who completed the OGTT. Those who had insulin resistance on OGTT were detected with the meal test. The 2-hour insulin levels following the meal were 38% higher than with the OGTT. Of 10 participants with insulin resistance, 9 had a total body fat mass greater than the 90th percentile, whereas 1 of 3 participants (33%) with normal body composition was insulin resistant.

CONCLUSION

Administration of oral glucose load via a meal is an effective alternative to the OGTT in diagnosing impaired glucose tolerance and insulin resistance and may be more sensitive, without the adverse effects of the oral glucose load in the OGTT. PCOS is an independent risk factor for impaired glucose tolerance and insulin resistance, regardless of body composition.

Effects of diet type and supplementation of glucosamine, chondroitin, and MSM on body composition, functional status, and markers of health in women with knee osteoarthritis initiating a resistance-based exercise and weight loss program

BACKGROUND

The purpose of this study was to determine whether sedentary obese women with knee OA initiating an exercise and weight loss program may experience more beneficial changes in body composition, functional capacity, and/or markers of health following a higher protein diet compared to a higher carbohydrate diet with or without GCM supplementation.

METHODS

Thirty sedentary women (54 ± 9 yrs, 163 ± 6 cm, 88.6 ± 13 kg, 46.1 ± 3% fat, 33.3 ± 5 kg/m2) with clinically diagnosed knee OA participated in a 14-week exercise and weight loss program. Participants followed an isoenergenic low fat higher carbohydrate (HC) or higher protein (HP) diet while participating in a supervised 30-minute circuit resistance-training program three times per week for 14-weeks. In a randomized and double blind manner, participants ingested supplements containing 1,500 mg/d of glucosamine (as d-glucosamine HCL), 1,200 mg/d of chondroitin sulfate (from chondroitin sulfate sodium), and 900 mg/d of methylsulfonylmethane or a placebo. At 0, 10, and 14-weeks, participants completed a battery of assessments. Data were analyzed by MANOVA with repeated measures.

RESULTS

Participants in both groups experienced significant reductions in body mass (-2.4 ± 3%), fat mass (-6.0 ± 6%), and body fat (-3.5 ± 4%) with no significant changes in fat free mass or resting energy expenditure. Perception of knee pain (-49 ± 39%) and knee stiffness (-42 ± 37%) was decreased while maximal strength (12%), muscular endurance (20%), balance indices (7% to 20%), lipid levels (-8% to -12%), homeostasis model assessment for estimating insulin resistance (-17%), leptin (-30%), and measures of physical functioning (59%), vitality (120%), and social function (66%) were improved in both groups with no differences among groups. Functional aerobic capacity was increased to a greater degree for those in the HP and GCM groups while there were some trends suggesting that supplementation affected perceptions of knee pain (p < 0.08).

CONCLUSIONS

Circuit style resistance-training and weight loss improved functional capacity in women with knee OA. The type of diet and dietary supplementation of GCM provided marginal additive benefits.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01271218.

Insulin resistance and the long-term consequences of polycystic ovary syndrome

In a significant number of women with the polycystic ovary syndrome there is impaired insulin metabolism with hypersecretion of insulin. Insulin resistance is defined as a diminution in the glucose response to a given amount of insulin. Insulin resistance has been implicated in the pathogenesis of many aspects of the syndrome. Hyperinsulinaemia leads to increased production of androgens resulting in anovulatory infertility. Women and particularly obese women with insulin resistance and the polycystic ovary syndrome have an increased risk of developing gestational diabetes and also type 2 diabetes and cardiovascular disease in later life. The women should be counselled about long-term health risks, and obese women with the polycystic ovary syndrome should be periodically screened. Lifestyle modification to reduce weight in obese women and treatment with insulin-sensitising drugs such as metformin in women with glucose intolerance result in the improvement of some metabolic abnormalities and hyperandrogenic disorders with the consequent restoration of normal menstrual and ovulatory function in a significant number of women with polycystic ovaries.

The definition of insulin resistance using HOMA-IR for Americans of Mexican descent using machine learning

Objective

The lack of standardized reference range for the homeostasis model assessment-estimated insulin resistance (HOMA-IR) index has limited its clinical application. This study defines the reference range of HOMA-IR index in an adult Hispanic population based with machine learning methods.

Methods

This study investigated a Hispanic population of 1854 adults, randomly selected on the basis of 2000 Census tract data in the city of Brownsville, Cameron County. Machine learning methods, support vector machine (SVM) and Bayesian Logistic Regression (BLR), were used to automatically identify measureable variables using standardized values that correlate with HOMA-IR; K-means clustering was then used to classify the individuals by insulin resistance.

Results

Our study showed that the best cutoff of HOMA-IR for identifying those with insulin resistance is 3.80. There are 39.1% individuals in this Hispanic population with HOMA-IR>3.80.

Conclusions

Our results are dramatically different using the popular clinical cutoff of 2.60. The high sensitivity and specificity of HOMA-IR>3.80 for insulin resistance provide a critical fundamental for our further efforts to improve the public health of this Hispanic population.

South Pacific Islanders resist type 2 diabetes: comparison of aerobic and resistance training

The purpose of this study was to evaluate the effectiveness of two exercise modalities for improving glycosylated hemoglobin (HbA1c) and associated clinical outcomes in Polynesian adults diagnosed with type 2 diabetes and visceral obesity. Twenty-six adults were randomized to receive resistance training or aerobic training, 3×/week, for 16 weeks. Dependent variables collected before and after intervention included: diabetes markers including HbA1c, blood lipids, relevant cytokines (C-reactive protein, adiponectin), and anthropometric and hemodynamic indices. Eighteen participants (72% female; age: 49.3 ± 5.3 years; waist circumference: 128.7 ± 18.7 cm) completed the intervention and follow-up assessments. Body mass index in the whole cohort at baseline indicated Class III (morbid) obesity (43.8 ± 9.5 kg/m(2)). Compliance to training was 73 ± 19 and 67 ± 18% in the aerobic and resistance training groups, respectively. HbA1c remained elevated in both groups after training. Aerobic training reduced systolic and diastolic blood pressure and increased serum triglycerides (all P < 0.05). No other exercise-induced adaptations were noted within or between groups. Post hoc analysis using pooled data indicated that higher adherence to training (≥75% attendance, n = 8) significantly reduced waist circumference (P < 0.001) and tended to reduce body weight and fasting insulin (all P ≤ 0.11) versus lower adherence (<75% attendance, n = 10). In conclusion, this study did not demonstrate an improvement in HbA1c with exercise in morbidly obese Polynesian people. Future investigations involving exercise regimens that are more practicable and which involve greater frequency and duration of training may be required to induce significant and clinically meaningful adaptations in this unique diabetes population.

A carbohydrate-restricted diet during resistance training promotes more favorable changes in body composition and markers of health in obese women with and without insulin resistance

OBJECTIVE

To determine whether sedentary obese women with elevated levels of homeostatic model assessment (HOMA) insulin resistance (ie, > 3.5) experience greater benefits from an exercise + higher-carbohydrate (HC) or carbohydrate-restricted weight loss program than women with lower HOMA levels.

METHODS

221 women (age, 46.5 ± 12 years; body weight, 90.3 ± 16 kg; body mass index, 33.8 ± 5 kg/m(2)) participated in a 10-week supervised exercise and weight loss program. The fitness program involved 30 minutes of circuit-style resistance training 3 days per week. Subjects were prescribed low-fat (30%) isoenergetic diets that consisted of 1200 kcals per day for 1 week (phase 1) and 1600 kcals per day for 9 weeks (phase 2) with HC or higher protein (HP). Fasting blood samples, body composition, anthropometry, resting energy expenditure, and fitness measurements were obtained at 0 and 10 weeks. Subjects were retrospectively stratified into lower (LH) or higher (HH) than 3.5 HOMA groups. Data were analyzed by multivariate analysis of variance with repeated measures and are presented as mean ± standard deviation changes from baseline.

RESULTS

Baseline HOMA levels in the LH group were significantly lower than those in the HH group (LH, 0.6 ± 0.7; HH, 6.3 ± 3.4; P = 0.001). Diet and training significantly decreased body weight (-3.5 ± 3 kg), fat mass (-2.7 ± 3 kg), blood glucose (-3%), total cholesterol (-4.5%), low-density lipoproteins (-5%), triglycerides (-5.9%), systolic blood pressure (-2.6%), and waist circumference (-3.7%), while increasing peak aerobic capacity (7.3%). Subjects in the HP group experienced greater weight loss (-4.4 ± 3.6 kg vs -2.6 ± 2.9 kg), fat loss (-3.4 ± 2.7 kg vs -1.7 ± 2.0 kg), reductions in serum glucose (3% vs 2%), and decreases in serum leptin levels (-30.8% vs -10.8%) than those in the HC group. Participants in the HH (-14.1%) and HP-HH (-21.6%) groups observed the greatest reduction in serum blood glucose.

CONCLUSION

A carbohydrate-restricted diet promoted more favorable changes in weight loss, fat loss, and markers of health in obese women who initiated an exercise program compared with a diet higher in carbohydrate. Additionally, obese women who initiated training and dieting with higher HOMA levels experienced greater reductions in blood glucose following an HP diet.

Comparison of high protein and high fiber weight-loss diets in women with risk factors for the metabolic syndrome: a randomized trial

BACKGROUND

Studies have suggested that moderately high protein diets may be more appropriate than conventional low-fat high carbohydrate diets for individuals at risk of developing the metabolic syndrome and type 2 diabetes. However in most such studies sources of dietary carbohydrate may not have been appropriate and protein intakes may have been excessively high. Thus, in a proof-of-concept study we compared two relatively low-fat weight loss diets - one high in protein and the other high in fiber-rich, minimally processed cereals and legumes - to determine whether a relatively high protein diet has the potential to confer greater benefits.

METHODS

Eighty-three overweight or obese women, 18-65 years, were randomized to either a moderately high protein (30% protein, 40% carbohydrate) diet (HP) or to a high fiber, relatively high carbohydrate (50% carbohydrate, > 35 g total dietary fiber, 20% protein) diet (HFib) for 8 weeks. Energy intakes were reduced by 2000 - 4000 kJ per day in order to achieve weight loss of between 0.5 and 1 kg per week.

RESULTS

Participants on both diets lost weight (HP: -4.5 kg [95% confidence interval (CI):-3.7, -5.4 kg] and HFib: -3.3 kg [95% CI: -4.2, -2.4 kg]), and reduced total body fat (HP: -4.0 kg [5% CI:-4.6, -3.4 kg] and HFib: -2.5 kg [95% CI: -3.5, -1.6 kg]), and waist circumference (HP: -5.4 cm [95% CI: -6.3, -4.5 cm] and HFib: -4.7 cm [95% CI: -5.8, -3.6 cm]), as well as total and LDL cholesterol, triglycerides, fasting plasma glucose and blood pressure. However participants on HP lost more body weight (-1.3 kg [95% CI: -2.5, -0.1 kg; p = 0.039]) and total body fat (-1.3 kg [95% CI: -2.4, -0.1; p = 0.029]). Diastolic blood pressure decreased more on HP (-3.7 mm Hg [95% CI: -6.2, -1.1; p = 0.005]).

CONCLUSIONS

A realistic high protein weight-reducing diet was associated with greater fat loss and lower blood pressure when compared with a high carbohydrate, high fiber diet in high risk overweight and obese women.

BMI and metabolic profile in patients with prolactinoma before and after treatment with dopamine agonists

Hyperprolactinemia might be related to weight gain, metabolic syndrome (MS), and insulin resistance (IR). Treatment with dopamine agonist (DA) has been shown to reduce body weight and improve metabolic parameters. The objectives of this study were to determine the prevalence of obesity, overweight, MS, and IR in patients with prolactinoma before and after therapy with DA and to evaluate the relation between prolactin (PRL), body weight, fat distribution, leptin levels, IR, and lipid profile before treatment. In addition, we investigated the correlation of the reduction in PRL levels with weight loss and metabolic profile improvement. Twenty-two patients with prolactinoma completed 6 months of treatment with DA. These patients were submitted to clinical (BMI, waist circumference, blood pressure (BP)), laboratory evaluation (leptin, glucose, low-density lipoprotein (LDL)-cholesterol, and triglyceride (TG) levels) and abdominal computed tomography (CT) before and after treatment. The statistical analyses were done by nonparametric tests. At the beginning of the study, the prevalence of obesity, overweight, MS, and IR was 45, 27, 27, and 18%, respectively. After 6 months of treatment with DA, PRL levels normalized, but no significant difference in BMI was observed. However, there was a significant decrease on homeostasis model assessment of insulin resistance (HOMA(IR)) index, glucose, LDL-cholesterol, and TG levels. This study suggests a possible involvement of prolactinoma on the prevalence of obesity. We should consider that DA may be effective on improving metabolic parameters, and we speculate that a period longer than 6 months of treatment is necessary to conclude whether this drug can interfere in the body weight of patients with prolactinoma.

A comparison of novel and commonly-used indices of insulin sensitivity in African American chronic hemodialysis patients

BACKGROUND

Insulin resistance (IR) is highly prevalent in chronic hemodialysis (CHD) patients and is associated with poor cardiovascular outcomes. Hyperinsulinemic euglycemic glucose clamp (HEGC) is the gold standard for measuring IR. The comparison of commonly-used indirect indices of IR to HEGC has not been adequately performed in this population. Furthermore, the validity of newly proposed adipokine-based IR indices has not been explored.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This is an observational study performed in a single center, involving 12 prevalent CHD patients (50 ± 9 years old, 100% African American, 33% women, body mass index of 34.4 ± 7.6 kg/m(2)) who were studied three consecutive times. IR was assessed by HEGC (glucose-disposal rate [GDR]), homeostatic model assessment of IR (HOMA-IR), HOMA-IR corrected by adiponectin (HOMA-AD), leptin adiponectin ratio (LAR), QUICKI, and the McAuley's index at each time point.

RESULTS

Eighty-three percent of the subjects displayed either glucose intolerance or overt insulin resistance by HEGC (GDR median, 5.71; interquartile range [IQR], 4.16, 6.81). LAR and HOMA-AD were the best correlates of IR measured by HEGC (r=-0.72, P<0.001, and -0.67, P<0.001), respectively. Fat percentage, interleukin-6, and adipokines (leptin, adiponectin, and resistin) were strongly associated with GDR. HEGC, LAR, and HOMA-AD had the best intraclass correlation coefficients.

CONCLUSION

IR is common in CHD patients. Adipokine-based indices are the best correlates of IR measurements by HEGC. HOMA-IR and QUICKI are reasonable alternatives. Use of these indices may allow better detection of alterations in insulin sensitivity in CHD patients.

How can we measure insulin sensitivity/resistance?

Insulin resistance represents a major public health problem, as it plays a major role in the pathophysiology of type 2 diabetes mellitus; it is also associated with increased cardiovascular risk and atherogenic dyslipidaemia, and is a central component of the cluster of metabolic abnormalities that comprise the metabolic syndrome. Thus, the development of tools to quantify insulin sensitivity/resistance has been the main objective of a number of studies. Insulin resistance can be estimated with the use of several biological measurements that evaluate different aspects of this complex situation. To that end, it requires various resources, ranging from just a single fasting blood sample for simple indices, such as the HOMA or QUICKI, to a research setting in which to perform the gold-standard hyperinsulinaemic-euglycaemic clamp test. The choice of method for evaluating insulin resistance depends on the nature of the information required (classification of individual subjects, group comparisons, precise measurement of either global, muscle or liver insulin sensitivity/resistance) and on the available resources. The aim of this review is to analyze the most frequently used assay methods in an attempt to evaluate when and why these methods may be useful.

The impact of insulin resistance on the outcome of laparoscopic ovarian diathermy in women with polycystic ovarian syndrome

OBJECTIVE

Insulin resistance (IR), which is common in women with polycystic ovarian syndrome (PCOS), may adversely affect the outcome of ovulation induction due to its detrimental effect on ovarian function. The aim of this study was to evaluate the impact of IR on the outcome of laparoscopic ovarian diathermy (LOD).

DESIGN

Prospective observational study.

SETTING

Tertiary fertility centre.

POPULATION

Forty-four anovulatory women with PCOS undergoing LOD.

METHODS

Fasting serum concentrations of insulin and glucose were measured before and after LOD. Insulin sensitivity was determined using the homeostasis model assessment (HOMA) index. Values of HOMA index ≥2.1 were considered abnormal, indicating IR.

MAIN OUTCOME MEASURES

Ovulation and pregnancy rates were compared between women with and without IR using χ(2) test and odds ratio (OR) with 95% confidence interval (CI).

RESULTS

Eighteen women (41%) had elevated HOMA index (≥2.1). There was no change of HOMA index after LOD (median 1.89, range 0.53-8.48 vs. 1.92, range 0.53-8.46). The ovulation rate in women with IR (12 of 18, 67%) was significantly (p=0.013, OR 0.08; 95% CI 0.01-0.74) lower than that (25 of 26, 96%) of women without IR. Likewise, the pregnancy rate (six of 18, 33%) was significantly (p=0.037, OR 0.26; 95% CI 0.07-0.94) lower in women with IR than that of women without IR (17 of 26, 65%). Using a receiver operating characteristics curve, the HOMA index was useful in predicting no ovulation after LOD (area under the curve 0.826).

CONCLUSIONS

Insulin resistance appears to have an adverse effect on the outcome of LOD and seems to be a useful prognostic factor.