Quantitative insulin sensitivity check index: a simple, accurate method for assessing insulin sensitivity in humans

The relation between two polymorphisms in the glucocorticoid receptor gene and body mass index, blood pressure and cholesterol in obese patients

OBJECTIVE

We have recently reported that, in healthy elderly Dutch individuals, a N363S polymorphism in the glucocorticoid receptor (GR) gene is associated with higher sensitivity to low-dose dexamethasone (0.25 mg), evaluated as both cortisol suppression and insulin response, and with an increased body mass index (BMI). In the present study we investigated the role of the N363S polymorphism, and a BclI restriction site polymorphism in a group of Italian patients with severe obesity.

DESIGN

Two hundred and seventy-nine patients (mean BMI 45.9 +/- 0.9 kg/m2) were genotyped using both PCR-restriction fragment length polymorphism analysis and Taqman Sequence Detection System. Determination of several metabolic and antropometric parameters was also performed in order to correlate them to the genotype.

RESULTS

In this group of obese patients, 13 subjects (eight female, five males) were heterozygous for the N363S variant (allelic frequency 2.3%) and had significantly higher BMI (P < 0.04), resting energy expenditure (P < 0.03) and food intake (P < 0.01) when compared to wild-type homozygotes. When the data were analysed according to sex, female heterozygotes for the N363S allele had significantly higher BMI (P = 0.04), resting energy expenditure (P = 0.03) and food intake (P = 0.008) than obese women with the wild-type 363 GR gene. Male carriers of this variant also had higher values for these variables although the differences did not reach statistical significance. A case-control study with homozygous wild-type obese subjects which were age-, sex- and BMI-matched, revealed no difference in resting energy expenditure and food intake. The allele frequency of the BclI variant was 27% (89 females and 41 males out of 269 subjects). No differences in anthropometric and metabolic parameters were found between subjects heterozygous or homozygous for this variant GR in this obese population. However, when we studied the effect of the presence of the BclI polymorphism and the N363S variant in the same individual, we found that the subjects who carried both polymorphisms had a tendency towards higher systolic and diastolic blood pressure and significantly higher total and LDL-cholesterol levels (P = 0.005 and P = 0.05, respectively).

DISCUSSION

Taking the results of this study and those obtained in the Dutch population, we speculate that heterozygous carriers of the N363S variant who develop obesity, may become even more obese, possibly because they have a hypersensitive insulin response and thus, via activation of lipogenesis, store fat more efficiently. Furthermore, these data suggest that N363S carriers who carry the BclI polymorphism as well, tend to have a slightly unfavourable cardiovascular profile.

Severe gastroesophageal reflux is associated with reduced carbon monoxide diffusing capacity

OBJECTIVE

To assess whether severe gastroesophageal reflux (GER) is associated with abnormalities in lung function including measures of lung volume and gas diffusion.

METHODS

Data from 147 patients with obesity (body mass index [BMI] range, 31.7 to 70 kg/m(2)) who presented for obesity surgery was analyzed retrospectively. A questionnaire was completed preoperatively that included a history of GER, frequency and severity of symptoms, investigations, and medications used. A history of lung disease, sleep-disordered breathing, and smoking also was obtained. A physician who was blinded to lung function graded GER severity prospectively by the results of pH monitoring and/or gastroscopy, and medication use. Spirometry, lung volumes, and gas transfer were measured preoperatively.

RESULTS

Patients with severe GER had reduced levels of the diffusing capacity of the lung for carbon monoxide (DLCO) [21.1 mL/min/mm Hg; 95% confidence interval (CI), 18.9 to 23.2], as measured by CO transfer, compared with those patients without GER (26.3 mL/min/mm Hg; 95% CI, 24.4 to 28.2; p = 0.001). This remained significant after adjusting for age, gender, BMI, and smoking history. Gas transfer corrected for lung volume also was reduced in the group with severe GER (4.6 mL/min/mm Hg per L; 95% CI, 4.3 to 4.9) compared to the group without GER (5.3 mL/min/mm Hg per L; 95% CI, 5.1 to 5.5; p = 0.001). There was no significant difference in other measures of lung function.

CONCLUSIONS

Severe GER is associated with an impairment of gas exchange. This may be due to microaspiration of gastric acid or fluid into the airways.

Changes in abdominal subcutaneous fat water content with rapid weight loss and long-term weight maintenance in abdominally obese men and women

OBJECTIVE

Insulin resistance decreases blood flow and volume in fat tissue. We hypothesised that fat tissue nutritive blood flow and volume, and thereby water content, would increase during weight loss and weight maintenance in obese persons.

DESIGN

Longitudinal clinical intervention with a 9-week very-low-calorie diet (VLCD) followed by one year of weight maintenance.

SUBJECTS

Obese men (n=13) and women (n=14) with the metabolic syndrome.

MEASUREMENTS

Water content of abdominal subcutaneous fat tissue as estimated by a sensor on the skin surface measuring the dielectric constant at 300 MHz. Anthropometric measures of fatness and fat distribution. Biochemical measures related to insulin resistance.

RESULTS

Subjects lost 14.5+/-3.4% of body weight during the VLCD, and generally sustained this weight loss during weight maintenance. Insulin sensitivity as estimated by an index (qualitative insulin sensitivity check index) increased during the VLCD, and remained increased throughout weight maintenance. The dielectric constant increased from 23.3+/-2.3 to 25.0+/-2.1 (P<0.001) during the VLCD, and further to 27.8+/-1.9 (P<0.001) during weight maintenance, indicating an increase in the water content of subcutaneous fat. The increase in subcutaneous fat water content did not correlate with weight loss and other measures of adiposity during the VLCD, but there was an inverse correlation that strengthened in significance from baseline to 6, 9 and 12 mo (r=-0.32 to -0.64, P=0.079-0.002). Increases in subcutaneous fat water content also correlated with improvements in insulin sensitivity at 6, 9 and 12 months of weight maintenance (r=0.34-0.54, P=0.094-0.006).

CONCLUSIONS

Water content of abdominal subcutaneous adipose tissue increases with weight loss in obese persons with the metabolic syndrome, and may reflect increased subcutaneous fat tissue nutritive blood flow. The increase in water content correlates with the increase in insulin sensitivity, suggesting that weight loss and consequent improved insulin sensitivity could mediate the increase in abdominal subcutaneous fat hydration.

Evaluation of insulin resistance in acromegalic patients before and after treatment with somatostatin analogues

Many studies have recently shown that simple computer-solved indices, based on fasting glucose and insulin levels, closely mirror the euglycemic clamp technique in studying insulin resistance or pancreatic insulin secretion. Few data are at present available on the evaluation of these novel indices in acromegalic patients, known to be GH-dependent insulin-resistant subjects, in particular during medical treatment with somatostatin analogues. Indeed, these drugs are able to inhibit not only GH and IGF-I levels, but also insulin and glucagon pancreatic secretion, with contrasting effects on glucose metabolism. In this study, insulin resistance was evaluated by the homeostasis model assessment (HOMA-IR) and insulin sensitivity by quantitative insulin check index (QUICKI) in 27 normoglycemic acromegalic patients, before and after 6-month therapy with somatostatin analogues (lanreotide-SR 30-60 mg every 7-28 days in 15 and octreotide-LAR 20-30 mg every 28 days in 12). Thirty-five age- and sex-matched healthy subjects and 17 surgically treated acromegalic patients (5 cured and 12 not cured) were studied as control groups. Before medical treatment, HOMA-IR was higher in acromegalic patients than in healthy controls (4 +/- 3 vs 1.7 +/- 0.7, p < 0.05), while QUICKI was lower (0.33 +/- 0.04 vs 0.36 +/- 0.03, p < 0.05). During medical therapy, HOMA-IR decreased to 2.4 +/- 1.6 (p < 0.05) and became similar to that recorded in both healthy subjects and surgically treated patients. However, fasting glucose was increased and fasting insulin was decreased. QUICKI did not significantly change from basal values. No differences were observed between patients who normalized or not hormonal levels. The effects of the 2 drugs, though higher glucose levels were seen in patients treated with octreotide-LAR. In conclusion, this study demonstrates that medical treatment is able to improve insulin resistance, even if only successful surgery is able to completely normalize both HOMA-IR and QUICKI.

The androgenic sex hormone profile is an essential feature of metabolic syndrome in premenopausal women: a controlled community-based study

OBJECTIVE

To evaluate sex hormones in premenopausal white women with metabolic syndrome (MBS).

DESIGN

Cross-sectional controlled community-based study.

SETTING

Pieksämäki District Health Center, Pieksämäki, Finland.

PATIENT(S)

Five hundred forty-three women, aged 34 to 54 years, were screened according to National Cholesterol Education Program criteria: waist >88 cm, hypertension >/=130/>/=85 mm Hg, hypertriglyceridemia >/=1.7 mmol/L, high-density lipoprotein (HDL)-cholesterol <1.3 mmol/L, and fasting glucose >/=6.1 mmol/L. Sixty-three women fulfilled at least three of the above-mentioned criteria and were enrolled. Eighty-eight age-matched women without MBS served as controls.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURES

Sex steroid levels in relation to insulin sensitivity and body composition.

RESULT(S)

A markedly lower insulin sensitivity index and higher free androgen index were detected in the women with MBS than in the controls. Abdominal obesity and increased diastolic blood pressure were significantly associated with high free androgen index in multiple regression analysis.

CONCLUSION(S)

A hyperandrogenic hormone profile appeared to be a typical feature of premenopausal female MBS even without polycystic ovary syndrome (PCOS).

Relative impact of insulin resistance and obesity on cardiovascular risk factors in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) affects 5% to 7% of women of reproductive age. Insulin resistance and obesity are components of this important syndrome that may contribute to excess cardiovascular risk. We analyzed data from 69 patients with PCOS who had undergone quantitative assessment of insulin sensitivity, blood pressure, lipid profiles, and androgen levels to determine the impact of insulin resistance and obesity on parameters of cardiovascular risk. Homeostasis model assessment (HOMA) was used to stratify patients in terms of insulin resistance. To obtain a reference population, we used data from the National Health and Nutrition Examination Study (NHANES III, 1988 to 1994). The most insulin-resistant tertile of patients exhibited higher body mass index (BMI), androgen levels, systolic and diastolic blood pressure (DBP), triglyceride (TG) levels, and decreased high-density lipoprotein cholesterol (HDL-C) levels. Insulin resistance, not BMI, was the main determinant of HDL-C and TG levels and systolic blood pressure (SBP) in PCOS. Among normal women, both BMI and insulin resistance influenced cardiovascular risk factors. Insulin resistance was a more significant predictor of TGs in women with PCOS than in normal women (P =.008). In contrast to normal women, insulin resistance in PCOS appears to be the prime determinant of abnormal lipids, blood pressure, and androgens. Thus, early detection of insulin resistance, as well as weight reduction, should be emphasized for all patients with PCOS.

Restoration of euglycemia and normal acute insulin response to glucose in obese subjects with type 2 diabetes following bariatric surgery

Insulin resistance and loss of glucose-stimulated acute insulin response (AIR) are the two major and earliest defects in the course of type 2 diabetes. We investigated whether weight loss after bariatric surgery in patients with morbid obesity and type 2 diabetes could restore euglycemia and normal AIR to an intravenous glucose tolerance test (IVGTT). We studied 25 morbidly obese patients-12 with type 2 diabetes, 5 with impaired glucose tolerance, and 8 with normal glucose tolerance (NGT)-before and after a biliopancreatic diversion (BPD) with Roux-en-Y gastric bypass (RYGBP). Twelve individuals with normal BMI served as control subjects. Twelve months after surgery, in the diabetes group, BMI decreased from 53.2 +/- 2.0 to 29.2 +/- 1.7 kg/m(2), fasting glucose decreased from 9.5 +/- 0.83 to 4.5 +/- 0.13 mmol/l, and fasting insulin decreased from 168.4 +/- 25.9 to 37.7 +/- 4.4 pmol/l (mean +/- SE; P < 0.001). AIR, the mean of insulin concentration at 2, 3, and 5 min over basal in the IVGTT, increased by 770 and 935% at 3 and 12 months after surgery, respectively (from 24.0 +/- 22.7 to 209 +/- 43.4 and 248 +/- 33.1 pmol/l, respectively; P < 0,001). Conversely, in the NGT group, the AIR decreased by 40.5% (from 660 +/- 60 to 393 +/- 93 pmol/l; P = 0.027) 12 months after surgery. BPD with RYGBP performed in morbidly obese patients with type 2 diabetes leads to significant weight loss, euglycemia, and normal insulin sensitivity; but most importantly, it restores a normal beta-cell AIR to glucose and a normal relationship of AIR to insulin sensitivity. This is the first study to demonstrate that the lost glucose-induced AIR in patients with type 2 diabetes of mild or moderate severity is a reversible abnormality.

Insulin sensitivity in young women with vasovagal syncope

BACKGROUND

Insulin, in addition to its known metabolic effects, has sympatho-excitatory and vasodilatory actions on muscular blood vessels. The goal of this study was to evaluate insulin sensitivity in young women with vasovagal syncope and positive tilt test results (HUT+) and to compare it with that in patients with negative tilt test results (HUT-) and in control subjects without a history of syncope.

METHODS

Different indices of insulin sensitivity were obtained by an oral glucose tolerance test (OGTT) in 13 young women with syncope and HUT+ (age 26.8 +/- 9.1 years, body mass index 20.4 +/- 2.1), 8 patients with HUT- (age 26 +/- 5.6 years, body mass index 21.9 +/- 2.4), and 13 control subjects without syncope and HUT- (age 28.9 +/- 8.8 years, body mass index 23.1 +/- 1.7). The following parameters were assessed: fasting glucose and insulin levels (G(0), I(0)); G(0)/I(0) ratio; G(0) x I(0); areas under the curve for glucose and insulin; homeostatic model assessment (HOMA); quantitative insulin sensitivity check index (QUICKI); and composite whole-body insulin sensitivity index (ISI).

RESULTS

G(0) and I(0) values were significantly lower in patients with HUT+ than in control subjects (G(0) 4.9 vs 81.9, P <.05, I(0) 4.7 vs 9.1, P <.005). All the fasting values-based indices (ie, HOMA 0.9 vs 1.9, P <.005) and the ISI (12.8 vs 7.1, P =.01) differed significantly in both groups. None of the parameters showed significant differences between patients with HUT- and control subjects. Sixty-one percent of patients with HUT+ had a vasovagal reaction during OGTT.

CONCLUSIONS

Young women with vasovagal syncope and HUT+ have a greater insulin sensitivity. They have a propensity to reproduce symptoms during the OGTT. This hypersensitivity could be one of the predisposing factors for vasovagal episodes.

A common polymorphism in the promoter of UCP2 contributes to the variation in insulin secretion in glucose-tolerant subjects

It was reported that the common -866G/A polymorphism in the promoter of the human uncoupling protein-2 (UCP2) gene, which enhances its trascriptional activity, is associated with increased mRNA levels in human adipocytes and reduced risk of obesity. Studies in knockout mice and beta-cells indicate that UCP2 may play a role in beta-cell function. In this study, we addressed the question of whether the common -866G/A polymorphism in UCP2 gene contributes to the variation of insulin secretion in humans by genotyping 301 nondiabetic subjects who underwent an oral glucose tolerance test. Glucose-stimulated insulin secretion estimated by several indexes of beta-cell function was significantly lower in carriers of the -866A/A genotype compared with -866A/G or -866G/G according to the dosage of the A allele (P = 0.002-0.05). To investigate directly whether the UCP2 -866G/A polymorphism affects human islet function, pancreatic islets isolated from two -866G/G homozygous, seven -866G/A heterozygous, and one -866A/A homozygous nondiabetic donors were studied. Islets from -866A/A homozygous had lower insulin secretion in response to glucose stimulation as compared with -866G/G and -866G/A carriers. These results indicate that the common -866G/A polymorphism in the UCP2 gene may contribute to the biological variation of insulin secretion in humans.

Success of laparoscopic ovarian wedge resection is related to obesity, lipid profile, and insulin levels

OBJECTIVE

To evaluate the effects of laparoscopic ovarian wedge resection on hormonal and metabolic parameters of polycystic ovary syndrome (PCOS) and to compare profiles of women who achieved pregnancy with those who did not.

DESIGN

Prospective study.

SETTING

University hospital.

PATIENT(S)

Thirty-three women with PCOS.

INTERVENTION(S)

Laparoscopic ovarian wedge resection using harmonic scalpel.

MAIN OUTCOME MEASURE(S)

Pregnancy; levels of testosterone, DHEAS, gonadotropins, sex hormone-binding globulin (SHBG), and glucose and insulin during 2-hour glucose tolerance test; lipid profile; body mass index; and waist-to-hip ratio.

RESULT(S)

Twenty-two women (67%) achieved clinical pregnancy within the mean of 4.9 months after surgery. Baseline parameters of women who became pregnant differed from those who did not: those who became pregnant were less obese, had lower levels of total cholesterol, low-density lipoprotein, and triglycerides; higher levels of SHBG; lower levels of fasting insulin; lower insulin area under the curve; and higher insulin sensitivity index. Subjects not pregnant by 12 weeks after surgery underwent repeat endocrine and metabolic evaluations. In these women, wedge resection was followed by declines in testosterone, LH, and insulin sensitivity index. Wedge resection had no significant effect on SHBG, DHEAS, or lipid profile.

CONCLUSION(S)

Laparoscopic wedge resections are associated with the highest pregnancy rates among less obese subjects with favorable lipid profiles and lower insulin. In this study, the postoperative decline of serum testosterone and LH is not attributable to improvement of insulin sensitivity.

Insulin resistance and its contribution to colon carcinogenesis

The insulin resistance-colon cancer hypothesis, stating that insulin resistance may be associated with the development of colorectal cancer, represents a significant advance in colon cancer, as it emphasizes the potential for this cancer to become a modifiable disease. The fact that the incidence of insulin resistance has been increasing in the United States and much of the rest of the Western world where colon cancer remains the second leading cause of cancer death makes the exploration of the interrelationship of these conditions a subject of high priority. Here, we review the salient features of insulin resistance, defined as impaired biological response to the action of insulin. Recent epidemiological studies, evaluating potential associations between colon cancer risk and diabetes mellitus, dietary intake and metabolic factors, and IGF levels in several clinical settings, provide strong support of the insulin resistance-colon cancer hypothesis (without establishing causality). Mechanistically, insulin resistance has been associated with hyperinsulinemia, increased levels of growth factors including IGF-1, and alterations in NF-kappaB and peroxisome proliferator-activated receptor signaling, which may promote colon cancer through their effects on colonocyte kinetics. It is a reasonable expectation that in the not too distant future, critical interventions to the already mapped molecular sequence of events, which link two apparently disparate entities, combined with lifestyle changes could abrogate the development of colon cancer.

QUICKI is a useful index of insulin sensitivity in subjects with hypertension

Insulin resistance may link disorders of metabolic homeostasis such as diabetes and obesity with disorders of hemodynamic homeostasis such as hypertension. Thus it is of interest to validate simple methods for quantifying insulin sensitivity in hypertensive patients. The quantitative insulin-sensitivity check index (QUICKI) is a novel mathematical transformation of fasting blood glucose and insulin levels. In obese and diabetic subjects, QUICKI has a significantly better linear correlation with glucose clamp determinations of insulin sensitivity than minimal-model estimates. To determine whether QUICKI is also useful in hypertensive subjects, we performed glucose clamps and frequently sampled intravenous glucose tolerance tests (FSIVGTT) on 27 hypertensive subjects taken off antihypertensive medication. Indexes of insulin sensitivity derived from glucose clamp studies (SIClamp) were compared with QUICKI, minimal-model analysis of FSIVGTTs (SIMM), and homeostasis model assessment (HOMA). The correlation between QUICKI and SIClamp ( r = 0.84) was significantly better than that between SIMM and SIClamp( r = 0.65; P < 0.028). The correlation between QUICKI and SIClamp was comparable to that between 1/HOMA and SIClamp ( r = 0.82). When studies were repeated in 14 subjects who had resumed antihypertensive medications, the percent changes in SIClamp for each of these patients were significantly correlated with percent changes in QUICKI ( r = 0.61) and HOMA ( r = −0.54) but not SIMM ( r = −0.18). We conclude that QUICKI is a simple, robust index of insulin sensitivity that is useful for evaluating and following the insulin resistance of hypertensive subjects in both research studies and clinical practice.

Detection of insulin resistance in Turkish adults: a hospital-based study

AIM

The aim of the present study was to investigate the usefulness of insulin sensitivity check indices in our hospital population.

METHODS

Both HOMA (insulin X glucose in mmol/l/22.5) and QUICKI (1/log insulin in microu/ml + log glucose in mg/dl) indices were calculated from fasting values in 1,774 subjects from the medical records of Baskent University Adana Hospital.

RESULTS

Subjects with diabetes, hyperlipidaemia and central obesity were characterized by significantly higher HOMA and lower QUICKI indices than those of healthy subjects. A fall in the QUICKI index (0.3469 +/- 0.028 in healthy subjects and 0.3247 +/- 0.025 in non-obese diabetics) as well as an increase in HOMA index (2.24 +/- 1.26 in healthy subjects and 3.59 +/- 2.08 in non-obese diabetics) corresponded to metabolic and clinical manifestations of insulin resistance in various groups of subjects. Age, low HDL cholesterol, male sex, type 2 DM and hypertension were independent risk factors for CAD. Age, male sex, waist circumference and CAD were found to be risk factors for hypertension. Fasting insulin and glucose levels contain sufficient information to assess insulin sensitivity over a wide range in a diverse population. The following can be accepted as mean values to assess insulin resistance in our hospital population: 0.3469 +/- 0.028 for the QUICKI index and 2.24 +/- 1.26 for the HOMA index

CONCLUSIONS

HOMA and QUICKI indices are simple and reproducible methods for determining insulin sensitivity in humans.

Testosterone levels in pregnant women correlate with the insulin response during the glucose tolerance test

OBJECTIVE

To evaluate the association between insulin/insulin-like growth factor I (IGF-I) systems and androgen levels in pregnancy.

DESIGN

Prospective cohort study.

SETTING

Yale University School of Medicine.

PATIENT(S)

Pregnant women undergoing a 100-gram 3-hour glucose tolerance test (GTT).

INTERVENTION(S)

Serum samples collected during GTT were analyzed for insulin, androgens, free IGF-I, insulin-like growth factor-binding protein (IGFBP) 1, and estriol.

MAIN OUTCOME MEASURE(S)

Observing the relationship between insulin/IGFs and androgen levels.

RESULT(S)

The insulin area under the curve (I(AUC)) during GTT correlated positively with total T and free T, but not with dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulphate (DHEAS), or estriol. The peak insulin values (I(max)) during GTT also correlated positively with total T and free T, but not with DHEA, DHEAS, or estriol. There was no statistically significant correlation of T levels with free IGF-I, IGFBP-1, glucose, DHEAS, or estriol. Multiple linear regression analysis modeling showed that I(AUC) and I(max) did have a statistically significant correlation with free T levels.

CONCLUSION(S)

This study demonstrates for the first time that I(AUC) and I(max) measured in hyperinsulinemic states such as pregnancy correlate with T levels. In view of the lack of correlation between insulin and DHEAS or estriol, insulin-related T production during pregnancy is likely of ovarian origin.

Insulin sensitivity and beta-cell secretion in thalassaemia major with secondary haemochromatosis: assessment by oral glucose tolerance test

Diabetes mellitus in patients with thalassaemia major is caused by secondary haemochromatosis due to transfusional iron overload. The pathogenetic mechanisms leading from siderosis to diabetes are still poorly understood. This study aimed at assessing the influence of insulin resistance and insulin deficiency on that process. Glucose, insulin and C-peptide levels during oral glucose tolerance tests (OGTT) from 36 thalassaemic patients with normal ( n=23), impaired ( n=6), or diabetic glucose tolerance ( n=7) and 32 control subjects were examined. Insulin secretion and insulin sensitivity were assessed by established calculated indices. Fasting, 2h and integrated glucose concentration were significantly increased in thalassaemic patients with normal glucose tolerance compared to controls (5.01/4.59 mmol/l, 6.33/5.17 mmol/l, and 844.2/739.3 mmol/l per min, respectively; all P<0.03). Patients with impaired glucose tolerance presented hyperinsulinaemia and delayed peak insulin during OGTT. The C-peptide/insulin ratio was decreased in patients with abnormal glucose tolerance compared to controls (5.85/7.33 x 10(3)pmol/l per min, P<0.03). It was negatively correlated with age in patients ( r=-0.45, P<0.01), but positively in controls ( r=0.43, P<0.03). Insulin sensitivity was significantly reduced in patients with impaired glucose tolerance or diabetes compared to controls. In addition, a significant decrease in patients with normal glucose tolerance was shown by two insulin sensitivity indices (all P<0.05). In thalassaemia patients, insulin sensitivity was negatively correlated with age. Insulin secretion capacity according to the homeostasis assessment model was significantly reduced in patient groups compared to controls (Kruskal-Wallis-test, P<0.004).

CONCLUSION

Insulin resistance is of central importance for the development of diabetes mellitus in patients with secondary haemochromatosis. An additional early defect in beta-cell secretion cannot be excluded.

Relationship between the growth hormone/insulin-like growth factor-I axis, insulin sensitivity, and adrenal androgens in normal prepubertal and pubertal girls

The aim of this study was to analyze the possible implication of changes in the GH/IGF-I axis and in insulin sensitivity for the regulation of adrenal androgen secretion of normal prepubertal and adolescent girls. A total of 61 normal girls were evaluated in prepuberty [Group (Gr)1, n = 33; early (Gr1A, n = 16) and late (Gr1B, n = 17)]; puberty (Gr3, n = 28), early (Gr3A, n = 9) and late (Gr3B, n = 19); and during the transition between prepuberty and puberty (Gr2, n = 26). Insulin sensitivity was estimated by the fasting glucose/insulin ratio (G/I). In Gr1, G/I was significantly higher, and the mean serum IGF-I and serum dehydroepiandrosterone sulfate (DHEAS) were significantly lower than in Gr3 (P < 0.0001). Mean G/I in Gr1A and Gr3A was significantly higher than in Gr1B (P < 0.01) and Gr3B (P < 0.02), respectively, and ratios in Gr1B were also significantly higher than in Gr3A (P < 0.02). However, body mass index (BMI) in Gr1A, Gr1B, and Gr3A was not significantly different, although a significant increment was observed between late prepuberty (Gr1B) and late puberty (Gr3B; P < 0.0001). On the other hand, serum IGF-I levels in Gr1A and Gr3A were significantly lower than those in Gr1B (P < 0.01) and Gr3B (P < 0.02), respectively. The mean serum DHEAS level in Gr1A and Gr3A was significantly lower than in Gr1B (P < 0.01) and Gr3B (P < 0.02), respectively, and the level in Gr1B was also significantly lower than in Gr3A (P < 0.02). Correlation studies within Gr1, Gr2, and Gr3 were also performed. There was a significant positive correlation between serum DHEAS and age and a significant negative correlation between serum DHEAS and G/I in the three groups. However, a significant positive correlation between serum DHEAS and serum IGF-I was only found in Gr1. Furthermore, a significant negative correlation between BMI and the G/I was found in Gr2 and Gr3. Therefore, changes in insulin sensitivity might be involved in adrenal androgen synthesis both in prepuberty and in puberty, as well as during the transition from prepuberty to puberty. Changes in BMI suggest that adiposity might be a mediator of this effect, particularly during late puberty. On the other hand, the GH/IGF axis might be an important metabolic signal involved in the maturational changes of human adrenal androgens during prepuberty, at the time of adrenarche. Indeed, a significant negative correlation between G/I and serum IGF-I was found in Gr1, as well as in Gr2. In conclusion, the findings of this study indicate that the GH/IGF-I axis and insulin resistance might be involved in the mechanism of adrenarche during prepuberty in normal girls. Because these relationships had not been seen in boys, we proposed that prepubertal ovarian estrogens might be responsible for the sex difference. The relationship between insulin resistance and adrenal androgens persists during the transition from prepuberty to puberty, as well as during puberty.

Polycystic ovary syndrome [PCOS]: comprehensive management in primary care

Polycystic ovary syndrome is a common premenopausal endocrino-metabolic disorder. In addition to hyperandrogenism, menstrual abnormalities, ovulatory disturbances and infertility, insulin resistance, dyslipidemia, and obesity may eventuate in long-term cardiovascular consequences.

Short-term triglyceride lowering with fenofibrate improves vasodilator function in subjects with hypertriglyceridemia

OBJECTIVE

The objective of this study was to investigate the effects of lowering plasma triglycerides (TGs) on endothelial function and gain insight into the role played by free fatty acids (FFAs) in hypertriglyceridemia-associated vascular dysfunction.

METHODS AND RESULTS

Eleven hypertriglyceridemic subjects without coronary artery disease, diabetes, elevated low-density lipoprotein cholesterol, tobacco use, or hypertension were studied using a randomized, double-blinded, crossover design (fenofibrate and placebo, 14 days). After each regimen, forearm blood flow was assessed by plethysmography in response to arterial acetylcholine, nitroprusside, and verapamil infusion. Hourly plasma TGs, FFA, glucose, and insulin were measured during a 24-hour feeding cycle to characterize the metabolic environment. Changes in plasma FFA after intravenous heparin were used to estimate typical FFA accumulation in the luminal endothelial microenvironment. Fenofibrate lowered plasma TG (P<0.001), total cholesterol (P<0.01), and apolipoprotein B (P<0.01) without altering high-density lipoprotein or low-density lipoprotein cholesterol concentrations. Forearm blood flow in response to acetylcholine (P<0.0001), nitroprusside (P<0.001), and verapamil (P<0.0001) improved after fenofibrate. Fenofibrate lowered 24-hour (P<0.0001) and post-heparin (P<0.001) TG and tended to lower 24-hour (P=0.054) and post-heparin (P=0.028) FFA.

CONCLUSIONS

Vascular smooth muscle function significantly improves after lowering plasma TG without changes in confounding lipoproteins or insulin resistance. The data raise additional questions regarding the role of FFA in hypertriglyceridemia-associated vascular dysfunction.

Prediction of type 2 diabetes using simple measures of insulin resistance: combined results from the San Antonio Heart Study, the Mexico City Diabetes Study, and the Insulin Resistance Atherosclerosis Study

To determine and formally compare the ability of simple indexes of insulin resistance (IR) to predict type 2 diabetes, we used combined prospective data from the San Antonio Heart Study, the Mexico City Diabetes Study, and the Insulin Resistance Atherosclerosis Study, which include well-characterized cohorts of non-Hispanic white, African-American, Hispanic American, and Mexican subjects with 5-8 years of follow-up. Poisson regression was used to assess the ability of each candidate index to predict incident diabetes at the follow-up examination (343 of 3,574 subjects developed diabetes). The areas under the receiver operator characteristic (AROC) curves for each index were calculated and statistically compared. In pooled analysis, Gutt et al.'s insulin sensitivity index at 0 and 120 min (ISI(0,120)) displayed the largest AROC (78.5%). This index was significantly more predictive (P < 0.0001) than a large group of indexes (including those by Belfiore, Avignon, Katz, and Stumvoll) that had AROC curves between 66 and 74%. These findings were essentially similar both after adjustment for covariates and when analyses were conducted separately by glucose tolerance status and ethnicity/study subgroups. In conclusion, we found substantial differences between published IR indexes in the prediction of diabetes, with ISI(0,120) consistently showing the strongest prediction. This index may reflect other aspects of diabetes pathogenesis in addition to IR, which might explain its strong predictive abilities despite its moderate correlation with direct measures of IR.

Intramyocellular lipid accumulation and reduced whole body lipid oxidation in HIV lipodystrophy

Antiretroviral therapy in human immunodeficiency virus (HIV)-positive patients can induce a lipodystrophy syndrome of peripheral fat wasting and central adiposity, dyslipidemia, and insulin resistance. To test whether in this syndrome insulin resistance is associated with abnormal muscle handling of fatty acids, 12 HIV-1 patients (8 females/4 males, age = 26 +/- 2 yr, HIV duration = 8 +/- 1 yr, body mass index = 22.0 +/- 1.0 kg/m(2), on protease inhibitors and nucleoside analog RT inhibitors) and 12 healthy subjects were studied. HIV-1 patients had a total body fat content (assessed by dual-energy X-ray absorptiometry) similar to that of controls (22 +/- 1 vs. 23 +/- 2%; P = 0.56), with a topographic fat redistribution characterized by reduced fat content in the legs (18 +/- 2 vs. 32 +/- 3%; P < 0.01) and increased fat content in the trunk (25 +/- 2 vs. 19 +/- 2%; P = 0.03). In HIV-positive patients, insulin sensitivity (assessed by QUICKI) was markedly impaired (0.341 +/- 0.011 vs. 0.376 +/- 0.007; P = 0.012). HIV-positive patients also had increased total plasma cholesterol (216 +/- 20 vs. 174 +/- 9 mg/dl; P = 0.05) and triglyceride (298 +/- 96 vs. 87 +/- 11 mg/dl; P = 0.03) concentrations. Muscular triglyceride content assessed by means of (1)H NMR spectroscopy was higher in HIV patients in soleus [92 +/- 12 vs. 42 +/- 5 arbitrary units (AU); P < 0.01] and tibialis anterior (26 +/- 6 vs. 11 +/- 3 AU; P = 0.04) muscles; in a stepwise regression analysis, it was strongly associated with QUICKI (R(2) = 0.27; P < 0.0093). Even if the basal metabolic rate (assessed by indirect calorimetry) was comparable to that of normal subjects, postabsorptive lipid oxidation was significantly impaired (0.30 +/- 0.07 vs. 0.88 +/- 0.09 mg x kg(-1) x min(-1); P < 0.01). In conclusion, lipodystrophy in HIV-1 patients in antiretroviral treatment is associated with intramuscular fat accumulation, which may mediate the development of the insulin resistance syndrome.

Polymorphisms of the insulin receptor substrate-2 in patients with type 2 diabetes

We investigated the significance of Gly1057Asp and Leu647Val insulin receptor substrate (IRS)-2 polymorphisms in two Italian cohorts comprising 186 glucose-tolerant subjects and 240 subjects with type 2 diabetes from the Lazio region (i.e. representative of central Italy), and 123 glucose-tolerant subjects from the Sicily region (i.e. representative of south Italy). The allelic frequency of Gly1057Asp variant did not differ between diabetics (32.9%) and nondiabetic subjects, whatever their ethnicity was (35.8% and 33.7% from Lazio and Sicily, respectively). As compared with Gly/Gly subjects within each group, Asp/Asp individuals showed no differences in quantitative traits, including fasting insulin and C-peptide, and several indices of insulin sensitivity and secretion. Only one of the diabetic patients was heterozygous for the Leu647Val variant, and none of the control subjects carried this variant. This patient had three children who were also heterozygous for this variant. They were glucose tolerant, and their insulin sensitivity and insulin secretion indices were within the range of age-matched controls. We also analyzed IRS-2 function in fibroblasts from carriers of Gly1057Asp or Leu647Val variant. No defects in IRS-2 expression, insulin-stimulated phosphorylation, or binding to the p85 subunit of phosphatidylinositol 3-kinase were observed. These results strongly argue against a major role of IRS-2 polymorphisms in the pathogenesis of type 2 diabetes.

Effects of an oral androgen on muscle and metabolism in older, community-dwelling men

To determine whether oxymetholone increases lean body mass (LBM) and skeletal muscle strength in older persons, 31 men 65-80 yr of age were randomized to placebo (group 1) or 50 mg (group 2) or 100 mg (group 3) daily for 12 wk. For the three groups, total LBM increased by 0.0 +/- 0.6, 3.3 +/- 1.2 (P < 0.001), and 4.2 +/- 2.4 kg (P < 0.001), respectively. Trunk fat decreased by 0.2 +/- 0.4, 1.7 +/- 1.0 (P = 0.018), and 2.2 +/- 0.9 kg (P = 0.005) in groups 1, 2, and 3, respectively. Relative increases in 1-repetition maximum (1-RM) strength for biaxial chest press of 8.2 +/- 9.2 and 13.9 +/- 8.1% in the two active treatment groups were significantly different from the change (-0.8 +/- 4.3%) for the placebo group (P < 0.03). For lat pull-down, 1-RM changed by -0.6 +/- 8.3, 8.8 +/- 15.1, and 18.4 +/- 21.0% for the groups, respectively (1-way ANOVA, P = 0.019). The pattern of changes among the groups for LBM and upper-body strength suggested that changes might be related to dose. Alanine aminotransferase increased by 72 +/- 67 U/l in group 3 (P < 0.001), and HDL-cholesterol decreased by -19 +/- 9 and -23 +/- 18 mg/dl in groups 2 and 3, respectively (P = 0.04 and P = 0.008). Thus oxymetholone improved LBM and maximal voluntary muscle strength and decreased fat mass in older men.

An inadequate glycaemic response to glucagon is linked to insulin resistance in preterm infants?

AIMS

To define clinical, metabolic, and hormonal characteristics of preterm infants relative to glucagon responsiveness.

METHODS

Two phase study of 78 preterm infants (25-36 weeks gestation) on regular four hourly feeds anticipating discharge home at 36 weeks mean corrected gestation. In phase 1 infants were fasted until hypoglycaemic, or maximally for eight hours. Endocrine and metabolic profiles were obtained at completion. Phase 2 was performed the following day. A feed was omitted and replaced by a bolus dose of intravenous glucagon (100 micro g/kg). Main outcome measures were measurements of blood glucose and lactate concentrations, taken immediately pre-glucagon, and thereafter every 15 minutes for 60 minutes. A rise in glucose concentration of >1 mmol/l (55 infants) was defined as an adequate response to glucagon. An inadequate glycaemic response was <1 mmol/l (23 infants).

RESULTS

Several differences in fasting blood glucose and hormone concentrations were identified in infants with an inadequate glycaemic response to glucagon compared to those with an adequate response: relative fasting hyperglycaemia (mean 3.7 v 3.3 mmol/l, p = 0.008); fasting hyperinsulinaemia (mean 4.3 v 2.6 mU/l, p = 0.014); an increased insulin:glucagon ratio (0.19 v 0.11, p = 0.014), and a lower insulin sensitivity QUICKI index (0.19 v 0.22, p = 0.04). There was no distinctive phenotype to reliably predict response to glucagon.

CONCLUSION

Some preterm infants show an inadequate glycaemic response to glucagon and have features suggestive of insulin resistance. The potential long term implications of such insulin resistance may have appreciable public health consequences.

Fasting plasma ghrelin levels are negatively correlated with insulin resistance and PAI-1, but not with leptin, in obese children and adolescents

Ghrelin is a novel growth hormone-releasing peptide isolated from human and rat stomach that induces weight gain by increasing food intake and reducing fat utilization. Although recent data indicate that ghrelin is downregulated in human adult obesity, the characteristics of human obesity are heterogeneous, especially in children and adolescents, and depend on the distribution of subcutaneous and visceral fat tissue. We measured fasting plasma ghrelin concentrations by radioimmunoassay in 49 obese Japanese children and adolescents (38 boys and 11 girls; mean age 10.2 +/- 2.8 years; BMI 28.0 +/- 4.5 kg/m(2), percent overweight 56.0 +/- 20.7%), and analyzed associations of their ghrelin concentrations with their body composition, insulin resistance, and adipocytokine concentrations. Fasting plasma ghrelin levels were negatively correlated with BMI and waist circumference, but not with percent overweight or percent body fat, whereas fasting leptin levels were positively correlated with all of the following parameters: BMI, waist circumference, percent overweight, and percent body fat. Plasma ghrelin levels were negatively correlated with fasting immunoreactive insulin, homeostasis model assessment insulin resistance index, and quantitative insulin sensitivity check index values. There was no correlation between plasma ghrelin and leptin, but ghrelin was negatively correlated with the PAI-1 concentrations. The results suggest that the downregulation of ghrelin secretion may be a consequence of higher insulin resistance associated with visceral fat accumulation and elevated PAI-1 concentrations, and not a consequence of total body fat accumulation associated with elevated leptin concentrations.

Fasting blood sample-based assessment of insulin sensitivity in kidney-pancreas-transplanted patients

OBJECTIVE

To ascertain whether simple indexes of insulin sensitivity based on a fasting blood sample may be reliable measures of insulin sensitivity in combined kidney-pancreas- transplanted patients.

RESEARCH DESIGN AND METHODS

Estimates of insulin sensitivity based on fasting plasma glucose, insulin (homeostasis model assessment of insulin sensitivity [HOMA-IS], Quantitative Insulin Sensitivity Check Index [QUICKI]), and free fatty acid (revised QUICKI) concentrations were compared with insulin sensitivity as assessed with the gold standard technique (euglycemic-hyperinsulinemic clamp) in 22 patients who had undergone kidney-pancreas transplantation (KP-Tx) and 18 matched healthy subjects (NOR).

RESULTS

In KP-Tx patients, indexes based on the glucose-insulin product, HOMA-IS (r = 0.47, P = 0.03) and QUICKI (r = 0.47, P = 0.03), were shown to be reliable measures of insulin sensitivity. The introduction of fasting plasma free fatty acid concentration in the revised QUICKI (r = 0.76, P < 0.0001) considerably improved the power of prediction of the clamp-based measure of insulin sensitivity as observed in the healthy control subjects (r = 0.83, P < 0.0001).

CONCLUSIONS

This study shows that in KP-Tx patients, HOMA-IS and QUICKI are reliable measures of insulin sensitivity; the additional incorporation of fasting plasma free fatty acid concentration into the glucose-insulin product (revised QUICKI) resulted in a considerably more powerful index.

Metabolic effects of nandrolone decanoate and resistance training in men with HIV

Thirty human immunodeficiency virus (HIV)-infected men were randomized to a high dose of nandrolone decanoate weekly (group 1) or nandrolone plus resistance training (group 2) for 12 wk. For the two groups, nandrolone had no significant effects on total cholesterol, LDL cholesterol, LDL phenotype, or fasting triglycerides, although triglycerides decreased by 66 +/- 124 mg/dl for the entire population (P = 0.01). Group 2 subjects had a favorable increase of 5.2 +/- 7.7A in LDL particle size (P = 0.03), whereas there was no change in group 1. Lipoprotein(a) decreased by 7.3 +/- 6.8 mg/dl for group 1 (P = 0.002) and by 6.9 +/- 8.1 for group 2 (P = 0.013). However, HDL cholesterol decreased by 8.7 +/- 7.4 mg/dl for group 1 (P < 0.001) and by 10.6 +/- 5.9 for group 2 (P < 0.001). Percentages of HDL(2b) (9.7-12 nm) and HDL(2a) (8.8-9.7 nm) subfractions decreased similarly for the two groups, whereas HDL(3a) (8.2-8.8 nm) and HDL(3b) (7.8-8.2 nm) increased in the groups during study therapy (P < or = 0.02 for all comparisons). There was no evidence of a decreased insulin sensitivity in either group, whereas fasting glucose, fasting insulin, and homeostasis model assessment improved in group 2 (P < 0.05). These metabolic effects were favorable (other than for HDL), but changes were generally transient (except for HDL in group 2), with measurements returning to baseline 2 mo after the interventions were completed.

Indices of insulin action, disposal, and secretion derived from fasting samples and clamps in normal glucose-tolerant black and white children

OBJECTIVE

To validate fasting indices of insulin sensitivity and secretion in a diverse pediatric population against gold standard estimates from euglycemic and hyperglycemic clamps.

RESEARCH DESIGN AND METHODS

A total of 31 children (mean BMI 25.1 +/- 4.9 kg/m(2), mean age 8.7 +/- 1.4 years, 15 girls and 16 boys, 12 black and 19 white) underwent euglycemic and hyperglycemic clamps 2-6 weeks apart to derive insulin sensitivity indices (SI (Eug clamp) and SI (Hyper clamp)). Fasting samples were used to derive the homeostasis model assessment of insulin resistance index (HOMA-IR), HOMA of percent beta-cell function (HOMA-B%), quantitative insulin sensitivity check index (QUICKI), insulinogenic index, antilipolytic insulin sensitivity index (ISI-FFA), and C-peptide-to-insulin ratio.

RESULTS

The QUICKI correlated best with SI (Eug clamp) (r = 0.69, P < 0.05) and had greater correlations to SI (Eug clamp) than did either SI (Hyper clamp) (r = 0.45, P < 0.05) or the HOMA-IR (r = -0.51, P < 0.05). Both fasting insulin and the insulinogenic index correlated well with first- and steady-phase insulin secretion (r's from 0.79 to 0.86, P < 0.05). HOMA-B% was not as highly correlated (r = 0.69-0.72, P < 0.05). Fasting C-peptide-to-insulin ratio was not significantly correlated with clamp-derived metabolic clearance rate of insulin. ISI-FFA was not correlated with the degree of free fatty acid suppression obtained from the clamps.

CONCLUSIONS

The QUICKI, fasting insulin, and the insulinogenic index all closely correlate with corresponding clamp-derived indices of insulin sensitivity and secretion in this diverse pediatric cohort. These results, if replicated in similarly diverse populations, suggest that estimates based on fasting samples can be used to rank order insulin secretion and sensitivity in pediatric cohorts.

Plasma adiponectin levels in overweight and obese Asians

OBJECTIVE

Hypoadiponectin has been documented in subjects with obesity, diabetes mellitus, or coronary heart disease, suggesting a potential use of plasma adiponectin in following the clinical progress in subjects with metabolic syndrome (MS). In this study, we investigated the plasma adiponectin levels in relation to the variables of MS among overweight/obese Asian subjects.

RESEARCH METHODS AND PROCEDURES

The plasma adiponectin, anthropometric and biochemical measurements, oral glucose tolerance tests (OGTT), and modified insulin suppression tests were performed on 180 overweight/obese Asian subjects [body mass index (BMI) >or= 23 kg/m(2)], including 47 subjects with morbid obesity (BMI >or= 40 kg/m(2)).

RESULTS

The plasma adiponectin levels negatively correlated with BMI, waist-to-hip ratio, fasting plasma glucose, insulin, triglyceride, uric acid levels, hyperinsulinemia, and glucose intolerance in OGTT, but positively with high-density lipoprotein-cholesterol. In contrast, they were not related to blood pressure and total cholesterol. Moreover, insulin sensitivity, measured by quantitative insulin sensitivity check index (QUICKI) or in insulin suppression tests, significantly correlated with the plasma adiponectin levels. Among morbidly obese subjects, only the waist-to-hip ratio correlated with the plasma adiponectin levels. Using multivariate linear regression models, the area under curve of plasma glucose in OGTT and high-density lipoprotein-cholesterol among the overweight/obese subjects and WHR among the morbidly obese subjects were significantly related to the plasma adiponectin levels after adjustment for other variables.

DISCUSSION

In overweight/obese Asians, the plasma adiponectin levels significantly correlated with various indices of MS except hypertension. Whether the plasma adiponectin level could be a suitable biomarker for following the clinical progress of MS warrants further investigation.

Gender differences in factors influencing insulin resistance in elderly hyperlipemic non-diabetic subjects

BACKGROUND

The increase in the prevalence of insulin resistance-related metabolic syndrome, a disorder that greatly increases the risk of diabetes, heart attack and stroke, is alarming. One of the most frequent and early symptoms of metabolic syndrome is hypertriglyceridemia. We examined the gender differences between various metabolic factors related to insulin resistance in elderly non-diabetic men and postmenopausal women of comparable age suffering from hypertriglyceridemia, and compared them with healthy subjects of equal age.

RESULTS

The indexes of insulin resistance HOMA IR and QUICKI were significantly higher in both hyperlipemic men and women than in controls; 95% confidence limits of hyperlipemic subjects did not overlap with controls. In both normolipemic and hyperlipemic men and women serum leptin correlated significantly with insulin resistance, while HDL-cholesterol correlated inversely with HOMA-IR only in women (both normo- and hyperlipemic), and serum tumor necrosis factor alpha (TNFalpha) only in hyperlipemic women. According to results of multiple regression analysis with HOMA-IR as a dependent variable, leptin played a significant role in determining insulin resistance in both genders, but--aside from leptin--triglycerides, TNFalpha and decreased HDL-cholesterol were significant determinants in women, while body mass index and decreased HDL-cholesterol were significant determinants in men. The coefficient of determination (R2) of HOMA IR by above mentioned metabolic variables was in women above 60%, in men only about 40%.

CONCLUSION

The significant role of serum leptin in determination of insulin resistance in both elderly men and postmenopausal women of equal age was confirmed. However, the study also revealed significant gender differences : in women a strong influence of triglycerides, TNFalpha and decreased HDL-cholesterol, in men only a mild role of BMI and decreased HDL-cholesterol.

Behavioral, metabolic, and molecular correlates of lower insulin sensitivity in Mexican-Americans

We determined whether lower insulin sensitivity persists in young, nonobese, nondiabetic Mexican-American [MA; n = 13, 27.0 +/- 2.0 yr, body mass index (BMI) 23.0 +/- 0.7] compared with non-Hispanic white (NHW; n = 13, 24.8 +/- 1.5 yr, BMI 22.8 +/- 0.6) males and females after accounting for cardiorespiratory fitness (maximal O(2) uptake), abdominal fat distribution (computed tomography scans), dietary intake (4-day records), and skeletal muscle insulin-signaling protein abundance from muscle biopsies (Western blot analysis). MA were significantly less insulin sensitive compared with their NHW counterparts when estimated by homeostatic model assessment of insulin resistance (MA: 1.53 +/- 0.22 vs. NHW: 0.87 +/- 0.16, P < 0.05) and the revised quantitative insulin sensitivity check index (MA: 0.45 +/- 0.08 vs. NHW: 0.58 +/- 0.19, P = 0.05). However, skeletal muscle protein abundance of insulin receptor-beta (IRbeta), phosphatidylinositol 3-kinase p85 subunit, Akt1, Akt2, and GLUT4 were not significantly different. Differences in indexes of insulin sensitivity lost significance after percent dietary intake of palmitic acid, palmitoleic acid, and skeletal muscle protein abundance of IRbeta were accounted for. We conclude that differences in insulin sensitivity between nonobese, nondiabetic MA and NHW persist after effects of chronic and acute exercise and total and abdominal fat distribution are accounted for. These differences may be mediated, in part, by dietary fat intake.

Clinical manifestations and insulin resistance (IR) in polycystic ovary syndrome (PCOS) among South Asians and Caucasians: is there a difference?

OBJECTIVE

Polycystic ovary syndrome (PCOS) is more prevalent in South Asian women residing in the UK than in Caucasians. Insulin resistance (IR) is central to the pathogenesis of PCOS, while type 2 diabetes is commoner in South Asians. We aimed to determine a possible ethnic difference in the clinical and biochemical characteristics of South Asian vs. Caucasian women with PCOS.

PATIENTS AND DESIGN

A case-control cross-sectional observational study of consecutive women with anovular PCOS (47 South Asians, 40 Caucasians) and their age-matched controls (11 South Asians and 22 Caucasians).

MEASUREMENTS

Index subjects: a questionnaire-based interview on clinical symptoms and family history; anthropometric measurements, clinical observations of the presence and degree of acne, hirsutism and acanthosis nigricans; transvaginal pelvic ultrasound; biochemical analyses of fasting blood sugar, fasting plasma insulin, fasting lipids, testosterone, and SHBG concentrations.

CONTROL GROUP

age- and weight-matched unrelated women from the same ethnic backgrounds without PCOS seeking treatment for male infertility were studied by similar methods to those used with the index subjects.

RESULTS

South Asians with PCOS presented at a younger age (age 26 +/- 4 vs. 30.1 +/- 5 years, P = 0.005). Body mass index (BMI) and waist : hip ratios were similar in the two affected cohorts. More South Asians had oligomenorrhoea commencing at a younger age. Hirsutism (Ferriman Gallwey score 18 vs. 7.5, P = 0.0001), acne, acanthosis nigricans and secondary infertility were significantly more prevalent in South Asians. The fasting glucose was similar (4.52 +/- 0.08 vs. 4.62 +/- 0.09 mmol/l, P = 0.25), the fasting insulin higher (89.4 +/- 8.9 vs. 48.6 +/- 4.8 pmol/l, P = 0.0001) and insulin sensitivity (IS) lower (0.335 +/- 0.005 vs. 0.357 +/- 0.002, P = 0.0001) among South Asians. Serum SHBG was significantly less in South Asians (35 +/- 3.3 vs. 55 +/- 9.4 nmol/l, P = 0.02), while serum testosterone was similar (2.69 +/- 0.11 vs. 2.64 +/- 0.13 nmol/l, P = 0.37).

CONCLUSIONS

We conclude that South Asians with anovular PCOS seek treatment at a younger age, have more severe symptoms, and have higher fasting insulin concentrations and lower insulin sensitivity than Caucasians.

Expanding the natural history of nonalcoholic steatohepatitis: from cryptogenic cirrhosis to hepatocellular carcinoma

BACKGROUND & AIMS

Nonalcoholic steatohepatitis (NASH) may progress to cirrhosis; whether NASH plays also a role in the development of hepatocellular carcinoma (HCC) is unknown.

METHODS

Among 641 cirrhosis-associated HCCs, we retrospectively identified 44 patients with cryptogenic cirrhosis (CC). Of these, 23 were actively followed up and were compared in a case-control study with viral- and alcohol-associated HCC. Family and personal history of diabetes, hypertension, coronary heart disease, dyslipidemia, obesity, and biochemical data were compared between groups. Iron status and presence of mutations in the HFE gene of familiar hemochromatosis were also determined.

RESULTS

Family history was not different in relation to etiology. The prevalence of obesity and diabetes was significantly higher in patients with CC. Although liver function was similar, CC patients had higher glucose, cholesterol, and triglyceride plasma levels, increased parameters of insulin resistance, and lower aminotransferase levels. Iron status and prevalence of mutations in the HFE gene did not differ. Logistic regression analysis identified in sequence hypertriglyceridemia, diabetes, and normal aminotransferases as independent factors associated with HCC arising in CC.

CONCLUSIONS

Features suggestive of NASH are more frequently observed in HCC arising in patients with CC than in age- and sex-matched HCC patients of well-defined viral or alcoholic etiology. HCC may represent a late complication of NASH-related cirrhosis.

CordyMax Cs-4 improves glucose metabolism and increases insulin sensitivity in normal rats

OBJECTIVE

To evaluate effects of CordyMax trade mark Cs-4, a mycelial fermentation product of Cordyceps sinensis, on improving glucose metabolism and insulin sensitivity.

DESIGN

An in vivo pharmacology study. Subjects and Study Interventions: Adult Wistar rats, male and female, were given CordyMax 250 or 500 mg/kg per day or placebo for 17 days by gavage.

OUTCOME MEASUREMENTS

Fasting blood glucose, fasting plasma insulin, glucose-insulin index, and oral glucose tolerance.

RESULTS

Rats fed Cs-4 at either 250 or 500 mg/kg showed significantly reduced fasting blood glucose after the 17-day treatment, by 27% and 24% from baselines respectively (both p < 0.001). Examination of fasting plasma insulin demonstrated a 37% decrease in the high dose treatment groups (p = 0.012). Glucose-insulin index, an index of insulin sensitivity, increased by 10% and 17% in both 250 and 500 mg/kg groups (p = 0.008 and p = 0.0001, respectively). Oral glucose tolerance tests showed significantly improved glucose tolerance at 0.5, 1.0, and 2.0 hours after oral administration of a bolus of glucose (the area under the glucose curve: p = 0.05-0.006), but no change at 5 hours.

CONCLUSION

CordyMax Cs-4 is effective in lowering basal blood glucose and plasma insulin, improving glucose metabolism by enhancing insulin sensitivity, and improving oral glucose tolerance.

Alcohol consumption in the severely obese: relationship with the metabolic syndrome

OBJECTIVE

The aim of this study was to examine the association between the clinical and biochemical features of the metabolic syndrome and quantity and type of alcohol intake in the severely obese.

RESEARCH METHODS AND PROCEDURES

A cross-sectional study was performed in 486 consecutive severely obese subjects. Data on alcohol consumption was collected by serial clinical interviews and a questionnaire. The relationship between alcohol intake and the clinical and serum chemistry features of the metabolic syndrome was analyzed by multiple statistical techniques. Laboratory measures included lipid profile, fasting blood glucose, hemoglobin A1c, and fasting serum insulin. An indirect index of insulin resistance was calculated using the log-transformed fasting insulin and glucose product.

RESULTS

There were 486 subjects, 84% women, with a mean age of 40.6 +/- 10 years (range, 16 to 71 years) and a body mass index of 45.3 +/- 7 kg/m(2) (range, 34 to 77 kg/m(2)). Alcohol consumers (N = 276) showed a marked reduction in the adjusted odds ratio of type 2 diabetes (odds ratio = 0.29; 95% confidence interval, 0.16 to 0.55) compared with rare or nonconsumers (N = 210). There was a U-shaped relationship between the amount and frequency of alcohol consumption and fasting triglyceride, fasting glucose, hemoglobin A1c, and index of insulin resistance measurements. Consumers of < 100 g/wk had more favorable measures. The effect was attenuated when diabetics were excluded from the analysis. Timing of alcohol consumption did not influence outcome measures.

DISCUSSION

Light-to-moderate alcohol consumption is associated with a lower prevalence of type 2 diabetes, reduced insulin resistance, and more favorable vascular risk profile in the severely obese. We would propose that light to moderate alcohol consumption should not be discouraged in the severely obese.

Diabetogenic effect of tacrolimus in South African patients undergoing kidney transplantation1

BACKGROUND

Diabetes mellitus (DM) is a complication of tacrolimus therapy. This prospective study evaluated the prevalence of DM in South African black and white patients receiving tacrolimus after kidney transplantation and factors that could identify patients before transplantation who may be at risk of developing DM.

METHODS

Fasting blood samples from 17 patients (11 black, 6 white) were analyzed immediately pretransplantation and at 1 and 3 months posttransplantation for glucose, HbAIC, insulin, C-peptide, free fatty acids, lipids, urea, and creatinine. Insulin resistance (IR) was calculated using the homeostasis model assessment (HOMA) and quantitative insulin sensitivity check index (QUICKI) formulas.

RESULTS

Eight patients (47%) became diabetic (six black, two white), and nine patients (five black, four white) remained nondiabetic. Mean glucose concentrations in the diabetic group were significantly higher at 1 month (P=0.03) and 3 months (P=0.01). Mean insulin level was also significantly raised at 3 months (P=0.01) as was HbAIC (P=0.001). C-peptide concentrations did not change significantly in either group. Significant correlations emerged between fasting glucose concentrations at 3 months posttransplantation and initial HOMA (r=0.486; P=0.048) and initial QUICKI (r=-0.582; P=0.014).

CONCLUSIONS

Occurrence of DM was high and somewhat greater in black patients. IR was the main mechanism involved, together with inadequate beta-cell compensation. IR pretransplantation predicts the subsequent development of DM.

Rationale and methods for the estimation of insulin secretion in a given patient: from research to clinical practice

Although the plasma insulin assay is now 40 years old, it is not widely used in clinical practice. However, simple methods (such as the various indexes relating fasting insulin to fasting glucose), the increase in plasma insulin at the 30th minute of an oral glucose tolerance test, and the increase in insulin or C-peptide after stimulation by glucagon are relatively reliable compared with more sophisticated approaches to assess beta-cell sensitivity to glucose, kinetics of insulin secretion, residual insulin secretion, or insulin sensitivity. But these measures are of no decisive help in distinguishing between the various forms of impaired fasting glucose or non-insulin-dependent diabetes, such as type 2 diabetes, slow type 1 diabetes, the various forms of maturity-onset diabetes of the young, or the mitochondrial genome defects. No data are available to show that the measurement of plasma insulin may be of help to adapt the treatment of a diabetic patient, except for the need of insulin therapy. There are some suggestions that fasting plasma insulin and, more precisely, the homeostasis model assessment indexes may help to predict the progression toward diabetes or the progressive deterioration of beta-cell function in diabetic patients.

Cardiovascular risk in rheumatoid arthritis versus osteoarthritis: acute phase response related decreased insulin sensitivity and high-density lipoprotein cholesterol as well as clustering of metabolic syndrome features in rheumatoid arthritis

Rheumatoid arthritis (RA) patients experience a markedly increased frequency of cardiovascular disease. We evaluated cardiovascular risk profiles in 79 RA patients and in 39 age-matched and sex-matched osteoarthritis (OA) patients. Laboratory tests comprised ultrasensitive C-reactive protein (CRP) and fasting lipids. Insulin sensitivity (IS) was determined by the Quantitative Insulin Sensitivity Check Index (QUICKI) in all OA patients and in 39 of the RA patients. Ten RA patients were on glucocorticoids. RA patients exercised more frequently than OA patients (chi2 = 3.9, P < 0.05). Nine RA patients and one OA patient had diabetes (chi2 = 4.5, P < 0.05). The median CRP, the mean QUICKI and the mean high-density lipoprotein (HDL) cholesterol were 9 mg/l (range, 0.5-395 mg/l), 0.344 (95% confidence interval [CI], 0.332-0.355) and 1.40 mmol/l (95% CI, 1.30-1.49 mmol/l) in RA patients, respectively, as compared with 2.7 mg/l (range, 0.3-15.9 mg/l), 0.369 (95% CI, 0.356-0.383) and 1.68 mmol/l (95% CI, 1.50-1.85 mmol/l) in OA patients. Each of these differences was significant (P < 0.05). After controlling for the CRP, the QUICKI was similar in RA and OA patients (P = 0.07), while the differences in HDL cholesterol were attenuated but still significant (P = 0.03). The CRP correlated with IS, while IS was associated with high HDL cholesterol and low triglycerides in RA patients and not in OA patients. A high CRP (>/= 8 mg/l) was associated with hypertension (chi2 = 7.4, P < 0.05) in RA patients. RA glucocorticoid and nonglucocorticoid users did not differ in IS and lipids (P > 0.05). Excess cardiovascular risk in RA patients as compared with OA patients includes the presence of decreased IS and HDL cholesterol in RA patients. The latter is only partially attributable to the acute phase response. The CRP, IS, HDL cholesterol, triglycerides and hypertension are inter-related in RA patients, whereas none of these relationships were found in OA patients.

Repeatability characteristics of simple indices of insulin resistance: implications for research applications

The objectives of this study were to evaluate test characteristics, such as normality of distribution, variation, and repeatability, of simple fasting measures of insulin sensitivity and to use the results to choose among these measures. Duplicate fasting samples of insulin and glucose were collected before 4 h of euglycemic hyperinsulinemic clamping using insulin infusion rates ranging from 40-600 mU/m2 x min. Currently recommended estimates of insulin sensitivity, including the fasting insulin, 40/insulin, the homeostasis model assessment, the logarithmic transformation of the homeostasis model assessment, and the Quantitative Insulin Sensitivity Check Index, were evaluated. The normality of distribution and the variability of the tests (coefficient of variation and discriminant ratio) were compared between the measures and against the "gold standard" hyperinsulinemic clamp. Data from 253 clamp studies in 152 subjects were examined, including 79 repeated studies for repeatability analysis. In subjects ranging from lean to diabetic, the log transformed fasting measures combining insulin and glucose had normal distributions and test characteristics superior to the other simple indices (logarithmic transformation of the homeostasis model assessment coefficient of variation, 0.55; discriminant ratio, 13; Quantitative Insulin Sensitivity Check Index coefficient of variation, 0.05; discriminant ratio, 10) and statistically comparable to euglycemic hyperinsulinemic clamps (coefficient of variation, 0.10; discriminant ratio, 6.4). These favorable characteristics helped explain the superior correlations of these measures with the hyperinsulinemic clamps among insulin-resistant subjects. Furthermore, therapeutic changes in insulin sensitivity were as readily demonstrated with these simple measures as with the hyperinsulinemic clamp. The test characteristics of the logarithmic transformation of the homeostasis model assessment and the Quantitative Insulin Sensitivity Check Index are superior to other simple indices of insulin sensitivity. This helps explain their excellent correlations with formal measures both at baseline and with changes in insulin sensitivity and supports their broader application in clinical research.

Incorporation of the fasting plasma FFA concentration into QUICKI improves its association with insulin sensitivity in nonobese individuals

Insulin resistance plays a major role in the pathophysiology of diabetes and is associated with obesity and cardiovascular disease. Excellent methods exist for the assessment of insulin sensitivity in the laboratory setting, such as the glucose clamp. However, these methods are not suitable for large population studies, and, thus, surrogate estimates of insulin sensitivity based on measurements in a single blood sample have been developed. Recently an index based on the logarithm and the reciprocal of the insulin-glucose product (QUICKI) has been proposed. QUICKI correlated with insulin sensitivity across the entire spectrum of glucose tolerance, but its performance was less satisfactory in normal subjects. Aim of this study was to ascertain whether the inclusion of fasting plasma free fatty acids concentration into QUICKI improves its association with insulin sensitivity in nonobese subjects. To test this hypothesis, we performed a euglycemic hyperinsulinemic clamp [40 mU/(m(2).min)] in 57 young, healthy, nonobese individuals with (n = 17) or without (n = 40) first-degree relatives affected by type 2 diabetes (the former group being an in vivo model of mild insulin resistance). We then compared the clamp-based index of insulin sensitivity with both QUICKI and a revised QUICKI, the latter index including the contribution of fasting free fatty acid concentration as well. The revised QUICKI considerably improved the relationship with the clamp-based index of insulin sensitivity (r = 0.51, P < 0.0001) with respect to QUICKI (r = 0.27, P < 0.05). In addition, the revised QUICKI revealed a reduction of insulin sensitivity in the offspring of type 2 diabetes (10%; P < 0.006) that QUICKI was unable to detect (3%; P = 0.28). In conclusion, this study suggests that the incorporation of fasting free fatty acid level into QUICKI is useful to improve its correlation with the clamp-based index of insulin sensitivity and its discriminatory power in case of mild insulin resistance. Further investigation is needed to ascertain its applicability to patients with obesity and type 2 diabetes.

Clinically useful estimates of insulin sensitivity during pregnancy: validation studies in women with normal glucose tolerance and gestational diabetes mellitus

OBJECTIVE

We examined whether selected indexes of insulin sensitivity derived from an oral glucose tolerance test (IS(OGTT)) or fasting glucose/insulin levels (IS(QUICKI) and IS(HOMA)) can be used to predict insulin sensitivity in women before and during pregnancy.

RESEARCH DESIGN AND METHODS

A 2-h euglycemic-hyperinsulinemic clamp (5 mmol/l glucose, 40 mU. m(-2). min(-1) insulin) and a 120-min oral glucose tolerance test (75 g load pregravid, 100 g pregnant) were repeated on 15 women (10 with normal glucose tolerance [NGT] and 5 with gestational diabetes mellitus [GDM]) pregravid and during both early (12-14 weeks) and late (34-36 weeks) pregnancy. An index of insulin sensitivity derived from the clamp (IS(CLAMP)) was obtained from glucose infusion rates adjusted for change in fat-free mass and endogenous glucose production measured using [6,6(-2)H(2)]glucose.

RESULTS

Univariate analysis using combined groups and periods of pregnancy resulted in significant correlations between IS(CLAMP) and IS(OGTT) (r(2) = 0.74, P < 0.0001), IS(QUICKI) (r(2) = 0.64, P < 0.0001), and IS(HOMA) (r(2) = 0.53, P < 0.0001). The IS(OGTT) provided a significantly better correlation (P < 0.0001) than either IS(QUICKI) or IS(HOMA.) Multivariate analysis showed a significant group effect (P < 0.0003) on the prediction model, and separate equations were developed for the NGT (r(2) = 0.64, P < 0.0001) and GDM (r(2) = 0.85, P < 0.0001) groups. When subdivided by period of pregnancy, the correlation between IS(CLAMP) and IS(OGTT) pregravid was r(2) = 0.63 (P = 0.0002), during early pregnancy was r(2) = 0.80 (P < 0.0001), and during late pregnancy was r(2) = 0.64 (P = 0.0002).

CONCLUSIONS

Estimates of insulin sensitivity from the IS(OGTT) during pregnancy were significantly better than from fasting glucose and insulin values. However, separate prediction equations are necessary for pregnant women with NGT and women with GDM.

TNF-alpha and hyperandrogenism: a clinical, biochemical, and molecular genetic study

To evaluate the role of TNF-alpha in the pathogenesis of hyperandrogenism, we have evaluated the serum TNF-alpha levels, as well as several polymorphisms in the promoter region of the TNF-alpha gene, in a group of 60 hyperandrogenic patients and 27 healthy controls matched for body mass index. Hyperandrogenic patients presented with mildly increased serum TNF-alpha levels as compared with controls (mean[median] +/- SD: 7.2[7.0] +/- 3.3 pg/ml vs. 5.6[4.4] +/- 4.0 pg/ml, P < 0.02). Although no differences in body mass index and insulin resistance indexes were observed between patients and controls, when subjects were classified by body weight, serum TNF-alpha was increased only in lean patients as compared with lean controls, but this difference was not statistically significant when comparing obese patients with obese controls. The TNF-alpha gene polymorphisms studied here (-1196C/T, -1125G/C, -1031T/C, -863C/A, -857C/T, -316G/A, -308G/A, -238G/A, and -163G/A) were equally distributed in hyperandrogenic patients and controls. However, carriers of the -308A variant presented with increased basal and leuprolide-stimulated serum androgens and 17-hydroxyprogesterone levels when considering patients and controls as a group. No differences were observed in serum TNF-alpha levels, body mass index, and insulin resistance indexes, depending on the presence or absence of these variants. In conclusion, our present results suggest that the TNF-alpha system might contribute to the pathogenesis of hyperandrogenism, independent of obesity and insulin resistance. However, elucidation of the precise mechanisms underlying the relationship between the TNF-alpha system and androgen excess is needed before considering TNF-alpha as a significant contributing factor to the development of hyperandrogenism.

Improved endothelial function with metformin in type 2 diabetes mellitus

OBJECTIVES

This study was designed to assess the effect of metformin on impaired endothelial function in type 2 diabetes mellitus.

BACKGROUND

Abnormalities in vascular endothelial function are well recognized among patients with type 2 (insulin-resistant) diabetes mellitus. Insulin resistance itself may be central to the pathogenesis of endothelial dysfunction. The effects of metformin, an antidiabetic agent that improves insulin sensitivity, on endothelial function have not been reported.

METHODS

Subjects with diet-treated type 2 diabetes but without the confounding collection of cardiovascular risk factors seen in the metabolic syndrome were treated with metformin 500 mg twice daily (n = 29) or placebo (n = 15) for 12 weeks. Before and after treatment, blood flow responses to intraarterial administration of endothelium-dependent (acetylcholine), endothelium-independent (sodium nitroprusside) and nitrate-independent (verapamil) vasodilators were measured using forearm plethysmography. Whole-body insulin resistance was assessed on both occasions using the homeostasis model (HOMA-IR).

RESULTS

Subjects who received metformin demonstrated statistically significant improvement in acetylcholine-stimulated flows compared with those treated with placebo (p = 0.0027 by 2-way analysis of variance), whereas no significant effect was seen on nitroprusside-stimulated (p = 0.27) or verapamil-stimulated (p = 0.40) flows. There was a significant improvement in insulin resistance with metformin (32.5% reduction in HOMA-IR, p = 0.01), and by stepwise multivariate analysis insulin resistance was the sole predictor of endothelium-dependent blood flow following treatment (r = -0.659, p = 0.0012).

CONCLUSIONS

Metformin treatment improved both insulin resistance and endothelial function, with a strong statistical link between these variables. This supports the concept of the central role of insulin resistance in the pathogenesis of endothelial dysfunction in type 2 diabetes mellitus. This has important implications for the investigation and treatment of vascular disease in patients with type 2 diabetes mellitus.

The effects of metformin on body mass index and glucose tolerance in obese adolescents with fasting hyperinsulinemia and a family history of type 2 diabetes

OBJECTIVES

The prevalence of type 2 diabetes in American adolescents has increased markedly during the past generation. Although the factors that contribute to the development of type 2 diabetes are complex and not wholly elucidated, the triad of severe obesity, hyperinsulinemia, and a family history of type 2 diabetes places a child at an increased risk for development of the disease. Current approaches to the prevention of type 2 diabetes, including dietary counseling and exercise, have had limited success. We reasoned that drugs that increase glucose tolerance in diabetic patients might prove useful in preventing the progression to glucose intolerance in high-risk patients. To that end, we conducted a double-blind, placebo-controlled study of the effects of metformin on body mass index (BMI), serum leptin, glucose tolerance, and serum lipids in obese adolescents with fasting hyperinsulinemia and a family history of type 2 diabetes.

METHODS

The study population consisted of 29 white and black adolescents aged 12 to 19 years. All had BMIs exceeding 30 kg/m(2). Criteria for enrollment included: 1) a fasting insulin concentration exceeding 15 microU/mL; and 2) at least 1 first- or second-degree relative with type 2 diabetes. All patients had fasting plasma glucose concentrations <110 mg% and hemoglobin A1c concentrations </=6.0%. All had normal linear growth and sexual development for age, with no marked hirsutism, severe acne, or menstrual irregularities characteristic of polycystic ovary syndrome. Eight participants had acanthosis nigricans. After baseline laboratory studies including a rapidly sampled intravenous glucose tolerance test, patients were randomized to receive metformin (500 mg twice daily) or a placebo for a total of 6 months. The effects of metformin on BMI standard deviation score, serum leptin, glucose tolerance, and serum lipids were analyzed. The study was double-blinded and included no specific dietary restrictions.

RESULTS

Metformin caused a decline of 0.12 standard deviation in BMI in study participants (-1.3% from baseline), and a 5.5% reduction in serum leptin in girls. In contrast, BMI and serum leptin rose 0.23 standard deviation (2.3%) and 16.2%, respectively, in the placebo group during the treatment period. Metformin caused a progressive decline in fasting blood glucose (from a mean of 84.9 to 75.1 mg%) and a reduction in fasting insulin levels (from 31.3 to 19.3 microU/mL). In contrast, fasting glucose levels in the placebo group rose slightly from 77.2 to 82.3 mg%, and fasting insulin levels did not change. Insulin sensitivity, as assessed by the ratio of fasting insulin to glucose concentrations and the quantitative insulin sensitivity check index (1/[log fasting insulin + log fasting glucose]) and homeostasis model assessment insulin resistance index (fasting insulin x fasting glucose/22.5) indices, increased slightly in the metformin-treated participants. However, the insulin sensitivity measured using Bergman's minimal model did not change. There were also no significant changes in glucose effectiveness, hemoglobin A1c, serum lipids, or serum lactate in the metformin or placebo groups. Metformin was tolerated well by the majority of patients. Transient abdominal discomfort or diarrhea occurred in 40% of treated participants; there were no episodes of vomiting or lactic acidosis.

CONCLUSIONS

The treatment of obesity and insulin resistance in adults often proves ineffective because the vicious cycle leading to type 2 diabetes may have become entrenched and, to some extent, may be irreversible. Early detection and therapy of the obese adolescent with a family history of type 2 diabetes may interrupt the cycle of weight gain and insulin resistance that leads to glucose intolerance in adulthood. Through its ability to reduce fasting blood glucose and insulin concentrations and to moderate weight gain, metformin might complement the effects of dietary and exercise counseling and reduce the risk of type 2 diabetes in selected patients.