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Kristina M Utzschneider

Publications and source records attributed to Kristina M Utzschneider.

16 recordsLinked to original sources
PubMed2025

Metaproteomic Analysis to Assess the Impact of Storage Media on Human Gut Microbiome in Fecal Samples.

The human gut microbiome is a diverse community of microorganisms residing in the gastrointestinal tract. The storage condition of fecal samples may impact the taxonomic and protein compositions of microbiomes in these samples. Here, we performed a mass spectrometry-based metaproteomic study to assess the impact of storage media on human gut microbiome in fecal samples. We evaluated FDA-authorized OMNIgene·GUT (OG), phosphate-buffered saline (PBS), and RNALater (RNAL) buffers and identified 38,185 microbial peptides corresponding to 7348 microbial proteins, which matched 16 phyla, 20 classes, 50 orders, 104 families, 332 genera, and 453 species. We found a high similarity among the fecal microbiomes preserved in OG, PBS, and RNAL in terms of the identification of proteins, taxa, and functional annotations. Both alpha and beta diversity suggested the high similarity among samples stored in the three media. Nonetheless, we also found some notable differences among buffers regarding the abundances of a few taxon groups. A partial human proteome (over 400 proteins) was identified in the fecal samples, with most of these proteins associated with the membrane and extracellular regions. The findings indicate the similarity among microbiomes in the fecal samples stored in OG, PBS, and RNAL regarding proteome profile, taxa, and functional capacity. SUMMARY: This study thoroughly analyzed and compared the metaproteomes of fecal samples preserved at -80°C in PBS, RNALater, and OMNIgene·GUT Dx buffers, offering novel insights into the effectiveness of these buffers in maintaining the stability and composition of the human gut microbiome. We found a high similarity in the identification and quantification of proteins, taxa, and functional annotations across the three buffers, with notable quantitative differences highlighting subtle yet important variations in preservation efficacy. The unique datasets and findings could offer valuable revelations into the impact of fecal sample preservation on translational and clinical analyses of the human gut microbiome.

Humans↗
PubMed2007

Glucose- and time-dependence of islet amyloid formation in vitro.

Islet amyloid contributes to the loss of beta-cell mass in type 2 diabetes. To examine the roles of glucose and time on amyloid formation, we developed a rapid in vitro model using isolated islets from human islet amyloid polypeptide (hIAPP) transgenic mice. Islets from hIAPP transgenic and non-transgenic mice were cultured for up to 7 days with either 5.5, 11.1, 16.7 or 33.3mmol/l glucose. At various time-points throughout the culture period, islets were harvested for determination of amyloid and beta-cell areas, and for measures of cell viability, insulin content, and secretion. Following culture of hIAPP transgenic islets in 16.7 or 33.3mmol/l glucose, amyloid formation was significantly increased compared to 5.5 or 11.1mmol/l glucose culture. Amyloid was detected as early as day 2 and increased in a time-dependent manner so that by day 7, a decrease in the proportion of beta-cell area in hIAPP transgenic islets was evident. When compared to non-transgenic islets after 7-day culture in 16.7mmol/l glucose, hIAPP transgenic islets were 24% less viable, had decreased beta-cell area and insulin content, but displayed no change in insulin secretion. Thus, we have developed a rapid in vitro model of light microscopy-visible islet amyloid formation that is both glucose- and time-dependent. Formation of amyloid in this model is associated with reduced cell viability and beta-cell loss but adequate functional adaptation. It thus enables studies investigating the mechanism(s) underlying the amyloid-associated loss of beta-cell mass in type 2 diabetes.

Amyloid↗
PubMed2006

Mechanisms linking obesity to insulin resistance and type 2 diabetes.

Obesity is associated with an increased risk of developing insulin resistance and type 2 diabetes. In obese individuals, adipose tissue releases increased amounts of non-esterified fatty acids, glycerol, hormones, pro-inflammatory cytokines and other factors that are involved in the development of insulin resistance. When insulin resistance is accompanied by dysfunction of pancreatic islet beta-cells - the cells that release insulin - failure to control blood glucose levels results. Abnormalities in beta-cell function are therefore critical in defining the risk and development of type 2 diabetes. This knowledge is fostering exploration of the molecular and genetic basis of the disease and new approaches to its treatment and prevention.

Diabetes Mellitus, Type 2↗
PubMed2006

Superiority of the Modification of Diet in Renal Disease equation over the Cockcroft-Gault equation in screening for impaired kidney function in Japanese Americans.

The Cockcroft-Gault and the Modification of Diet in Renal Disease (MDRD) Study equations have not been validated in Asian Americans with varying degrees of glucose tolerance. We compared both equations to 24-h urinary creatinine clearance, the latter as a standard measurement of glomerular filtration rate (GFR), in 398 Japanese Americans (62.1+/-5.8 years, mean+/-S.D.) who had normal glucose tolerance (NGT) (n=138), impaired glucose tolerance (IGT) (n=136) and diabetes (n=124). Although both the Cockcroft-Gault (r=0.65, P<0.001) and the MDRD (r=0.74, P<0.001) equations correlated well with creatinine clearance, the latter was significantly superior (P=0.013 between r values). Receiver operating characteristic (ROC) curve analysis showed that the area under the curve (AUC) for the MDRD equation was significantly greater than for the Cockcroft-Gault equation (AUC 0.86 versus 0.80, P=0.015) in classifying subjects as having mildly reduced GFR (<90ml/min per 1.73m(2)). However, both equations overestimated the number of individuals with decreased GFR. We conclude therefore that while the MDRD equation more accurately identifies Asians who are in the early stages of kidney disease, as for other groups, a correction term appears necessary in order to reduce the number of Asian subjects being falsely diagnosed with CKD.

Aged↗
PubMed2006

Review: The role of insulin resistance in nonalcoholic fatty liver disease.

CONTEXT: Insulin resistance is an almost universal finding in nonalcoholic fatty liver disease (NAFLD). This review outlines the evidence linking insulin resistance and NAFLD, explores whether liver fat is a cause or consequence of insulin resistance, and reviews the current evidence for treatment of NAFLD. EVIDENCE ACQUISITION: Evidence from epidemiological, experimental, and clinical research studies investigating NAFLD and insulin resistance was reviewed. EVIDENCE SYNTHESIS: Insulin resistance in NAFLD is characterized by reductions in whole-body, hepatic, and adipose tissue insulin sensitivity. The mechanisms underlying the accumulation of fat in the liver may include excess dietary fat, increased delivery of free fatty acids to the liver, inadequate fatty acid oxidation, and increased de novo lipogenesis. Insulin resistance may enhance hepatic fat accumulation by increasing free fatty acid delivery and by the effect of hyperinsulinemia to stimulate anabolic processes. The impact of weight loss, metformin, and thiazolidinediones, all treatments aimed at improving insulin sensitivity, as well as other agents such as vitamin E, have been evaluated in patients with NAFLD and have shown some benefit. However, most intervention studies have been small and uncontrolled. CONCLUSION: Insulin resistance is a major feature of NAFLD that, in some patients, can progress to steatohepatitis. Treatments aimed at reducing insulin resistance have had some success, but larger placebo-controlled studies are needed to fully establish the efficacy of these interventions and possibly others in reducing the deleterious effects of fat accumulation in the liver.

Cytokines↗
PubMed2006

Effects of sex and hormone replacement therapy use on the prevalence of isolated impaired fasting glucose and isolated impaired glucose tolerance in subjects with a family history of type 2 diabetes.

Impaired fasting glucose (IFG) is more prevalent in men and impaired glucose tolerance (IGT) more prevalent in women. To explore whether this sex difference is related to female sex hormones, we performed a cross-sectional analysis of data from 2,164 (1,329 women and 835 men) first-degree relatives of individuals with type 2 diabetes. Subjects were categorized based on a 75-g oral glucose tolerance test. Sex and hormone replacement therapy (HRT) effects on the distribution of glucose tolerance were assessed using multinomial logistic regression corrected for familial clustering. Compared with men, women were more likely to have isolated IGT (relative risk 1.8 [95% CI 1.3-2.5]) and less likely to have isolated IFG (0.5 [0.3-0.7]) adjusted for ethnicity, age, waist, fasting insulin, and early insulin release (DeltaI(0-30)/DeltaG(0-30)). To evaluate HRT effects, postmenopausal women using (n = 238) or not using (n = 378) HRT were compared. HRT users were more likely to have isolated IGT (2.2 [1.2-4.0]) after adjustment, but the prevalence of isolated IFG did not differ by HRT status. Based on the influence of sex and HRT on the prevalence of isolated IFG and isolated IGT, we conclude that female sex hormones may play an important role in the pathogenesis of IFG and IGT.

Adult↗
PubMed2006

Gestational diabetes mellitus increases the risk of cardiovascular disease in women with a family history of type 2 diabetes.

OBJECTIVE: We sought to determine whether a history of gestational diabetes mellitus (GDM) further increases the risk of cardiovascular disease (CVD) in parous women with first-degree relatives with type 2 diabetes. RESEARCH DESIGN AND METHODS: Women with (n = 332) and without (n = 663) a history of GDM were compared regarding 1) the revised National Cholesterol Education Program Adult Treatment Panel III metabolic syndrome criteria, 2) the prevalence of type 2 diabetes, and 3) self-reported CVD. RESULTS: Women with prior GDM were younger (48.6 +/- 0.7 vs. 52.4 +/- 0.6 years [means +/- SE];P < 0.001) and less likely to be postmenopausal (48.3 vs. 57.9%; P < 0.005). Although both groups were obese (BMI 34.4 +/- 1.2 vs. 33.7 +/- 0.6 kg/m(2)), women with prior GDM were more likely to have metabolic syndrome (86.6 vs. 73.5%; P < 0.001) and type 2 diabetes (93.4 vs. 63.3%; P < 0.001). Moreover, they had a higher prevalence of CVD (15.5 vs. 12.4%; adjusted odds ratio 1.85 [95% CI 1.21-2.82];P = 0.005) that occurred at a younger age (45.5 +/- 2.2 vs. 52.5 +/- 1.9 years;P = 0.02) and was independent of metabolic syndrome (1.74 [1.10-2.76]; P = 0.02) and type 2 diabetes (1.56 [1.002-2.43];P < 0.05). CONCLUSIONS: Among women with a family history of type 2 diabetes, those with prior GDM were even more likely to not only have CVD risk factors, including metabolic syndrome and type 2 diabetes, but also to have experienced CVD events, which occurred at a younger age. Thus, women with both a family history of type 2 diabetes and personal history of GDM may be especially suitable for early interventions aimed at preventing or reducing their risk of CVD and diabetes.

Blood Glucose↗
PubMed2006

Impact of differences in fasting glucose and glucose tolerance on the hyperbolic relationship between insulin sensitivity and insulin responses.

OBJECTIVE: To determine whether the hyperbolic relationship between insulin sensitivity and the acute insulin response to glucose (AIRg) exists in subjects with impaired fasting glucose (IFG) or decreased glucose tolerance. RESEARCH DESIGN AND METHODS: We studied 219 healthy subjects (88 male and 131 female subjects, aged 26-75 years) with fasting plasma glucose (FPG) <6.11 mmol/l. Subjects underwent an intravenous glucose tolerance test to determine the insulin sensitivity index (Si), AIRg, and the glucose disappearance constant (Kg), the latter a measure of intravenous glucose tolerance. RESULTS: Si and AIRg were inversely related for the entire cohort, and this relationship was not significantly different from hyperbolic. The inverse relationship between Si and AIRg was not significantly different when compared between groups based on fasting glucose (normal fasting glucose [NFG], FPG <5.56 mmol/l vs. IFG, FPG 5.56-6.11 mmol/l) or by the Kg quartile. However, the curve relating Si and AIRg was left shifted in the IFG compared with NFG group (P < 0.001) and was progressively more left shifted with decreasing Kg (P < 0.001), consistent with decreasing beta-cell function. These changes were not observed for the curves relating Si and fasting insulin, suggesting that in the fasting state beta-cell function is maintained even in patients with mild IFG. Finally, the disposition index (DI) (Si x AIRg) was calculated as a measure of beta-cell function. The DI progressively decreased with increasing FPG, even in the group of subjects classified as NFG. CONCLUSIONS: The inverse relationship between insulin sensitivity and AIRg is consistent with a hyperbola not only in subjects with normal glucose tolerance but also with mild IFG or decreased Kg. Based on a hyperbolic relationship, a decrease in beta-cell function can be detected as FPG increases, even in patients who are normal glucose tolerant.

Adult↗
PubMed2005

Genetic background determines the extent of islet amyloid formation in human islet amyloid polypeptide transgenic mice.

Genetic background is important in determining susceptibility to metabolic abnormalities such as insulin resistance and beta-cell dysfunction. Islet amyloid is associated with reduced beta-cell mass and function and develops in the majority of our C57BL/6J x DBA/2J (F(1)) male human islet amyloid polypeptide (hIAPP) transgenic mice after 1 yr of increased fat feeding. To determine the relative contribution of each parental strain, C57BL/6J (BL6) and DBA/2J (DBA2), to islet amyloid formation, we studied male hIAPP mice on each background strain (BL6, n = 13; and DBA2 n = 11) and C57BL/6J x DBA/2J F(1) mice (n = 17) on a 9% (wt/wt) fat diet for 1 yr. At the end of 12 mo, islet amyloid deposition was quantified from thioflavin S-stained pancreas sections. The majority of mice in all groups developed islet amyloid (BL6: 91%, F(1): 76%, DBA2: 100%). However, the prevalence (%amyloid-positive islets; BL6: 14 +/- 3%, F(1): 44 +/- 8%, DBA2: 49 +/- 9%, P < 0.05) and severity (%islet area occupied by amyloid; BL6: 0.03 +/- 0.01%, F(1): 9.2 +/- 2.9%, DBA2: 5.7 +/- 2.3%, p < or = 0.01) were significantly lower in BL6 than F(1) and DBA2 mice. Increased islet amyloid severity was negatively correlated with insulin-positive area per islet, in F(1) (r(2) = 0.75, P < 0.001) and DBA2 (r(2) = 0.87, P < 0.001) mice but not BL6 mice (r(2) = 0.07). In summary, the extent of islet amyloid formation in hIAPP transgenic mice is determined by background strain, with mice expressing DBA/2J genes (F(1) and DBA2 mice) being more susceptible to amyloid deposition that replaces beta-cell mass. These findings underscore the importance of genetic and environmental factors in studying metabolic disease.

Amyloid↗
PubMed2005

A reduced-fat diet and aerobic exercise in Japanese Americans with impaired glucose tolerance decreases intra-abdominal fat and improves insulin sensitivity but not beta-cell function.

Lifestyle modification reduces the risk of developing type 2 diabetes and may have its effect through improving insulin sensitivity, beta-cell function, or both. To determine whether diet and exercise improve insulin sensitivity and/or beta-cell function and to evaluate these effects over time, we quantified insulin sensitivity and the acute insulin response to glucose (AIRg) in 62 Japanese Americans (age 56.5 +/- 1.3 years; mean +/- SE) with impaired glucose tolerance (IGT) who were randomized to the American Heart Association (AHA) Step 2 diet plus endurance exercise (n = 30) versus the AHA Step 1 diet plus stretching (n = 32) for 24 months. beta-Cell function (disposition index [DI]) was calculated as S(i) x AIRg, where S(i) is the insulin sensitivity index. The incremental area under the curve for glucose (incAUCg) was calculated from a 75-g oral glucose tolerance test. Intra-abdominal fat (IAF) and subcutaneous fat (SCF) areas were measured by computed tomography. At 24 months, the Step 2/endurance group had lower weight (63.1 +/- 2.4 vs. 71.3 +/- 2.9 kg; P = 0.004) and IAF (75.0 +/- 7.9 vs. 112.7 +/- 10.4 cm(2); P = 0.03) and SCF (196.5 +/- 18.0 vs. 227.7 +/- 19.9 cm(2); P < 0.001) areas, greater S(i) (4.7 +/- 0.5 vs. 3.3 +/- 0.3 x 10(-5) min . pmol(-1) . l(-1); P = 0.01), and a trend toward lower AIRg (294.9 +/- 50.0 vs. 305.4 +/- 30.0 pmol/l; P = 0.06) and incAUCg (8,217.3 +/- 350.7 vs. 8,902.0 +/- 367.2 mg . dl(-1) . 2 h(-1); P = 0.08) compared with the Step 1/stretching group after adjusting for baseline values. There was no difference in the DI (P = 0.7) between the groups. S(i) was associated with changes in weight (r = -0.426, P = 0.001) and IAF (r = -0.395, P = 0.003) and SCF (r = -0.341, P = 0.01) areas. Thus, the lifestyle modifications decreased weight and central adiposity and improved insulin sensitivity in Japanese Americans with IGT. However, such changes did not improve beta-cell function, suggesting that this degree of lifestyle modifications may be limited in preventing type 2 diabetes over the long term.

Abdomen↗
PubMed2005

Long-term treatment with rosiglitazone and metformin reduces the extent of, but does not prevent, islet amyloid deposition in mice expressing the gene for human islet amyloid polypeptide.

Islet amyloid deposition in type 2 diabetes is associated with reduced beta-cell mass. Therefore, interventions aimed at reducing islet amyloid formation may help preserve beta-cell mass in type 2 diabetes. Rosiglitazone and metformin act by different mechanisms to improve insulin sensitivity and thereby reduce beta-cell secretory demand, resulting in decreased release of insulin and islet amyloid polypeptide (IAPP), the unique constituent of islet amyloid deposits. We hypothesized that this reduced beta-cell secretory demand would lead to reduced islet amyloid formation. Human IAPP (hIAPP) transgenic mice, a model of islet amyloid, were treated for 12 months with rosiglitazone (1.5 mg.kg(-1).day(-1), n = 19), metformin (1 g.kg(-1).day(-1), n = 18), or control (n = 17). At the end of the study, islet amyloid prevalence (percent islets containing amyloid) and severity (percent islet area occupied by amyloid), islet mass, beta-cell mass, and insulin release were determined. Islet amyloid prevalence (44 +/- 8, 13 +/- 4, and 11 +/- 3% for control, metformin-, and rosiglitazone-treated mice, respectively) and severity (9.2 +/- 3.0, 0.22 +/- 0.11, and 0.10 +/- 0.05% for control, metformin-, and rosiglitazone-treated mice, respectively) were markedly reduced with both rosiglitazone (P < 0.001 for both measures) and metformin treatment (P < 0.001 for both measures). Both treatments were associated with reduced insulin release assessed as the acute insulin response to intravenous glucose (2,189 +/- 857, 621 +/- 256, and 14 +/- 158 pmol/l for control, metformin-, and rosiglitazone-treated mice, respectively; P < 0.05 for metformin vs. control and P < 0.005 for rosiglitazone vs. control), consistent with reduced secretory demand. Similarly, islet mass (33.4 +/- 7.0, 16.6 +/- 3.6, and 12.2 +/- 2.1 mg for control, metformin-, and rosiglitazone-treated mice, respectively) was not different with metformin treatment (P = 0.06 vs. control) but was significantly lower with rosiglitazone treatment (P < 0.05 vs. control). When the decreased islet mass was accounted for, the islet amyloid-related decrease in beta-cell mass (percent beta-cell mass/islet mass) was ameliorated in both rosiglitazone- and metformin-treated animals (57.9 +/- 3.1, 64.7 +/- 1.4, and 66.1 +/- 1.6% for control, metformin-, and rosiglitazone-treated mice, respectively; P < 0.05 for metformin or rosiglitazone vs. control). In summary, rosiglitazone and metformin protect beta-cells from the deleterious effects of islet amyloid, and this effect may contribute to the ability of these treatments to alleviate the progressive loss of beta-cell mass and function in type 2 diabetes.

Amyloid↗
PubMed2004

Diet-induced weight loss is associated with an improvement in beta-cell function in older men.

Although weight loss in older subjects has been shown to improve insulin sensitivity, it is unclear what effect this lifestyle intervention has on beta-cell function. To determine whether diet-induced weight loss can improve beta-cell function in older subjects, we studied 19 healthy male subjects (age, 65.4 +/- 0.9 yr; body mass index, 30.9 +/- 0.6 kg/m2; mean +/- SEM) before and after a 3-month 1200-kcal/d diet. The insulin sensitivity index (SI) was quantified using Bergman's minimal model. The acute insulin response to glucose (AIRg) and the maximal glucose-potentiated insulin response (AIRmax) were determined and then adjusted for SI (SI x AIRg and SI x AIRmax), thus providing measures of beta-cell function. Subjects demonstrated significant weight loss (95.6 +/- 2.4 to 86.1 +/- 2.5 kg; P < 0.001). Both fasting plasma glucose [97.3 +/- 1.6 to 95.1 +/- 1.3 mg/dl (5.4 +/- 0.09 to 5.3 +/- 0.07 mM); P = 0.05] and insulin [18.5 +/- 1.3 to 12.2 +/- 1.0 microU/ml (110.9 +/- 7.7 to 73.5 +/- 5.9 pM); P < 0.001] levels decreased. With weight loss, SI increased [1.59 +/- 0.24 to 2.49 +/- 0.32 x 10(-4) min(-1)/(microU/ml) (2.65 +/- 0.4 to 4.15 +/- 0.5 x 10(-5) min(-1)/pM); P < 0.001], whereas both AIRg [63.4 +/- 13.4 to 51.0 +/- 10.7 microU/ml (380 +/- 80 to 306 +/- 64 pM); P < 0.05] and AIRmax [314 +/- 31.4 to 259.9 +/- 33.4 microU/ml (1886 +/- 188 to 1560 +/- 200 pM); P < 0.05] decreased. Overall beta-cell function improved (SI x AIRg, 9.63 +/- 2.28 to 12.78 +/- 2.58 x 10(-3) min(-1), P < 0.05; and SI x AIRmax, 51.01 +/- 9.2 to 72.69 +/- 13.4 x 10(-3) min(-1), P < 0.05). Thus, the weight loss-associated improvements in both insulin sensitivity and beta-cell function may explain the beneficial effects of a lifestyle intervention on delaying the development of diabetes in older subjects.

Age Factors↗
PubMed2004

Impact of intra-abdominal fat and age on insulin sensitivity and beta-cell function.

The prevalence of glucose intolerance and type 2 diabetes increases with age. To determine whether the hyperbolic relationship between insulin sensitivity and the insulin response is affected by age and whether the decline in beta-cell function with age is related to increases in intra-abdominal fat or age per se, we studied 220 healthy subjects with fasting glucose <6.1 mmol/l (89 men and 131 women, aged 26-75 years, BMI 18.7-40.4 kg/m(2)). The insulin sensitivity index (S(i)) and the acute insulin response to glucose (AIRg) were determined, and from these beta-cell function was estimated as the disposition index (S(i) x AIRg). Intra-abdominal fat and subcutaneous fat areas were quantified by computed tomography. S(i) (5.40 +/- 0.5 vs. 7.86 +/- 0.7 x10(-5) min(-1)/[pmol/l]), P < 0.01) was decreased and intra-abdominal fat (117 +/- 10 vs. 81 +/- 9 cm(2), P < 0.05) was increased in the oldest (age 60-75 years) versus the youngest (age 26-44 years) quartile. The hyperbolic relationship between S(i) and AIRg was present independent of age; thus, beta-cell function measured as the disposition index (1,412 +/- 120 vs. 2,125 +/- 150 x10(-5) min(-1), P < 0.01) was lower in the oldest versus the youngest quartile. In multiple regression, intra-abdominal fat (r = -0.470, P < 0.001) but not age was associated with S(i), but both intra-abdominal fat (r = -0.198, P = 0.003) and age (r = -0.131, P = 0.05) were correlated with the disposition index. These data suggest that although intra-abdominal fat is a strong determinant of insulin sensitivity and beta-cell function, age has an independent effect on beta-cell function that may contribute to the increased prevalence of type 2 diabetes in older populations.

Abdomen↗
PubMed2004

Intra-abdominal fat is a major determinant of the National Cholesterol Education Program Adult Treatment Panel III criteria for the metabolic syndrome.

The underlying pathophysiology of the metabolic syndrome is the subject of debate, with both insulin resistance and obesity considered as important factors. We evaluated the differential effects of insulin resistance and central body fat distribution in determining the metabolic syndrome as defined by the National Cholesterol Education Program (NCEP) Adult Treatment Panel III. In addition, we determined which NCEP criteria were associated with insulin resistance and central adiposity. The subjects, 218 healthy men (n = 89) and women (n = 129) with a broad range of age (26-75 years) and BMI (18.4-46.8 kg/m2), underwent quantification of the insulin sensitivity index (Si) and intra-abdominal fat (IAF) and subcutaneous fat (SCF) areas. The metabolic syndrome was present in 34 (15.6%) of subjects who had a lower Si [median: 3.13 vs. 6.09 x 10(-5) min(-1)/(pmol/l)] and higher IAF (166.3 vs. 79.1 cm2) and SCF (285.1 vs. 179.8 cm2) areas compared with subjects without the syndrome (P < 0.001). Multivariate models including Si, IAF, and SCF demonstrated that each parameter was associated with the syndrome. However, IAF was independently associated with all five of the metabolic syndrome criteria. In multivariable models containing the criteria as covariates, waist circumference and triglyceride levels were independently associated with Si and IAF and SCF areas (P < 0.001). Although insulin resistance and central body fat are both associated with the metabolic syndrome, IAF is independently associated with all of the criteria, suggesting that it may have a pathophysiological role. Of the NCEP criteria, waist circumference and triglycerides may best identify insulin resistance and visceral adiposity in individuals with a fasting plasma glucose <6.4 mmol/l.

Abdomen↗
PubMed2003

Complex distribution, not absolute amount of adiponectin, correlates with thiazolidinedione-mediated improvement in insulin sensitivity.

Adiponectin is an adipocyte-specific secretory protein that circulates in serum as a hexamer of relatively low molecular weight (LMW) and a larger multimeric structure of high molecular weight (HMW). Serum levels of the protein correlate with systemic insulin sensitivity. The full-length protein affects hepatic gluconeogenesis through improved insulin sensitivity, and a proteolytic fragment of adiponectin stimulates beta oxidation in muscle. Here, we show that the ratio, and not the absolute amounts, between these two oligomeric forms (HMW to LMW) is critical in determining insulin sensitivity. We define a new index, S(A), that can be calculated as the ratio of HMW/(HMW + LMW). db/db mice, despite similar total adiponectin levels, display decreased S(A) values compared with wild type littermates, as do type II diabetic patients compared with insulin-sensitive individuals. Furthermore, S(A) improves with peroxisome proliferator-activated receptor-gamma agonist treatment (thiazolidinedione; TZD) in mice and humans. We demonstrate that changes in S(A) in a number of type 2 diabetic cohorts serve as a quantitative indicator of improvements in insulin sensitivity obtained during TZD treatment, whereas changes in total serum adiponectin levels do not correlate well at the individual level. Acute alterations in S(A) (DeltaS(A)) are strongly correlated with improvements in hepatic insulin sensitivity and are less relevant as an indicator of improved muscle insulin sensitivity in response to TZD treatment, further underscoring the conclusions from previous clamp studies that suggested that the liver is the primary site of action for the full-length protein. These observations suggest that the HMW adiponectin complex is the active form of this protein, which we directly demonstrate in vivo by its ability to depress serum glucose levels in a dose-dependent manner.

3T3-L1 Cells↗