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[Cross-sectional study of the relation between carboxypeptidase-H antibody and islet beta cell function in patients with latent autoimmune diabetes in adults].

OBJECTIVE: To explore the relation between carboxypeptidase-H antibody (CPH-Ab) and islet beta cell function in patients with latent autoimmune diabetes in adults (LADA) and to further confirm the diagnostic value of CPH-Ab for LADA. METHODS: Five hundred and forty-five patients who were initially diagnosed as Type 2 diabetes mellitus (T2DM) were tested with CPH-Ab and GAD-Ab by radioligand assay (RLA). T2DM patients, according to CPH-Ab and GAD-Ab status, were divided into CPH-Ab(+) group, GAD-Ab(+) group, and Ab(-) group to compare their islet beta cell function [represented by fasting C-peptide (FCP) and 2h postprandial C-peptide (2hCP)]. The relation between CPH-Ab and islet beta cell function in LADA was analyzed. RESULTS: The fasting C-peptide level in CPH-Ab(+) patients was between that of GAD-Ab(+) patients and that of Ab(-) patients (P<0.05), and the difference was still significant when the 3 groups were stratified with duration of disease (All P<0.05), but not with body mess index (all P>0.05). Corrected by concomitant variables including age, age at onset, duration of disease, and sex, the differences among the 3 groups were statistically significant (both P<0.001). Among the 3 groups FCP was lower than Ab(-) group in CPH-Ab(+) (P<0.05) and both FCP and PCP were lower than Ab(-) group in GAD-Ab(+) group (P<0.05 and P<0.01). The proportions of patients with insulin deficiency in CPH-Ab(+), GAD-Ab(+), and Ab(-) group were 27.6% (8/29), 48.1% (8/52) and 13.5% (54/400), respectively, which were significantly different among the 3 groups (P<0.001). GAD-Ab, BMI, and fasting blood glucose had effects on FCP and PCP in T2DM patients (All P<0.05), while CPH-Ab did not enter the equation in multivariable stepwise regressive analysis (P>0.05). CONCLUSION: The effect of CPH-Ab is less marked than that of GAD-Ab on islet beta-cell function in LADA patients. The value of CPH-Ab for the failure of islet beta-cell function in LADA should be determined prospectively.

Adult↗

Acute insulin response is an independent predictor of type 2 diabetes mellitus in individuals with both normal fasting and 2-h plasma glucose concentrations.

BACKGROUND: Earlier prospective studies have identified insulin action and secretion as predictors of T2DM in populations with normal glucose tolerance (NGT) and impaired glucose tolerance (IGT) (2-h OGTT < 7.8 and 7.8-11 mmol/L, respectively). Fasting plasma glucose (FPG), an additional and recently modified (normal <5.6 mmol/L) diagnostic criterion is associated with insulin secretion. We wanted to establish whether insulin secretion persists as an independent predictor of T2DM in individuals with no clinical evidence of impaired glucose regulation based on FPG and 2-h plasma glucose concentrations. METHODS: Insulin action (M, euglycemic-hyperinsulinemic clamp), insulin secretion (acute insulin response (AIR), IVGTT), and adiposity (%Fat, DXA or densitometry) were compared at baseline in 358 Pima Indians (232M/126F, 18-44 years old) with normal glucose regulation of whom 61 (35M/26F) developed diabetes (DIAB) during a median follow-up time of 7.6 years. RESULTS: In proportional-hazard analysis, % Fat (HR = 1.52, p = 0.03), M (HR = 0.51, p = 0.04) and AIR (HR = 0.64, p = 0.003) predicted the development of diabetes after adjustment for age and sex. In regression analysis adjusting for age, sex, %Fat and M at baseline, the non-diabetic group (NON-DM) had a higher AIR (p = 0.0002) than the DIAB group; the positive association of AIR with adiposity observed in the NON-DM group was absent in the DIAB group. Cumulative incidence rates (12y) for diabetes were highest (48%) in subjects with both M and AIR below the population median and lowest (11%) in subjects with both M and AIR above the population median. CONCLUSION: AIR can predict diabetes prior to the current clinical indicators of impaired glucose regulation.

Adiposity↗

Differential effect of pioglitazone (PGZ) and rosiglitazone (RGZ) on postprandial glucose and lipid metabolism in patients with type 2 diabetes mellitus: a prospective, randomized crossover study.

BACKGROUND: Postprandial metabolism is impaired in patients with type 2 diabetes (T2Dm). Two thiazolidinediones pioglitazone (PGZ) and rosiglitazone (RGZ) have similar effects on glycaemic control but differ in their effects on fasting lipids. This study investigated the effects of RGZ and PGZ on postprandial metabolism in a prospective, randomized crossover trial. METHODS: Seventeen patients with T2Dm were randomized to RGZ or PGZ for 12 weeks, with an 8-week wash-out period. Fasting blood samples were taken for glucose (FPG), insulin, HbA(1c), lipids, apolipoproteins (apo), lipoprotein (LPL) and hepatic lipase (HL), and cholesterol ester transfer protein (CETP) activity. A standardized breakfast was served and postprandial glucose, insulin, and lipid subfraction profiles were determined. RESULTS: RGZ and PGZ treatment resulted in a similar improvement in FPG, HbA(1c) and homeostasis model assessment. Fasting and postprandial triglyceride (TG) levels were significantly lower following PGZ therapy (fasting: -0.35 vs 0.44 mmol/L; p < 0.04; postprandial AUC-TG: -195.6 vs 127.9 mmol/L/min; p < 0.02) associated with changes in VLDL-2-TG (-0.10 vs 0.21 mmol/L; p = 0.23) and VLDL-3-TG (0.0 vs 0.34 mmol/L; p < 0.04). Fasting cholesterol increased with RGZ compared to PGZ (0.06 vs 0.59 mmol/L; p < 0.04), particularly in VLDL-2-C (-0.30 vs 0.59 mmol/L; p < 0.03) and VLDL-3-C (-0.85 vs 2.11 mmol/L; p < 0.02). Postprandial VLDL lipid and protein content increased after RGZ and decreased after PGZ. Fasting apoB, apoA-I, apoC-II/C-III-ratio, and LPL activity did not differ. CETP activity decreased after RGZ and increased after PGZ (-6.2 vs 4.2 p/mol/mL/min; p < 0.002). CONCLUSIONS: Both the glitazones had similar effects on glucose metabolism. The additional beneficial effect of PGZ on lipid metabolism may be related to its effects on insulin-independent VLDL production and CETP activity.

Blood Glucose↗

Variant screening of PRKAB2, a type 2 diabetes mellitus susceptibility candidate gene on 1q in Pima Indians.

The AMP-activated protein kinase (AMPK) is a key enzyme involved in the regulation of lipid and glucose metabolism. There are multiple isoforms of the three subunits of this enzymatic complex, each encoded by a different gene in humans. We have investigated the PRKAB2 gene encoding the beta2 subunit, which is located on chromosome 1q within a region linked with type 2 diabetes mellitus (T2DM) in the Pima Indians and four different Caucasian populations. The gene consists of eight exons spanning about 15 kb, and we detected nine variants in the introns and 3' UTR, including eight informative single nucleotide polymorphisms (SNPs) and one rare 4 bp insertion/deletion. In an analysis of representative markers in selected Pima Indians including 149 diabetic cases (onset age < 25 years) and 150 controls (at least 45 years old, with normal glucose tolerance), we found no evidence for association of this locus with T2DM. We conclude that variants in PRKAB2 are unlikely to contribute to the disease susceptibility in Pima Indians.

AMP-Activated Protein Kinases↗

Expression of resistin protein in normal human subcutaneous adipose tissue and pregnant women subcutaneous adipose tissue and placenta.

The expression of resistin protein in normal human abdominal, thigh, pregnant women abdominal, non-pregnant women abdominal subcutaneous adipose tissue and placenta and the relationship between obesity, type 2 diabetes mellitus (T2DM), pregnant physiological insulin resistance (IR) and gestational diabetes mellitus (GDM) was investigated. The expression of resistin protein in normal human abdominal, thigh, pregnant women abdominal, non-pregnant women abdominal subcutaneous adipose tissue and placenta was detected by using Western blotting method. Fasting serum glucose concentration was measured by glucose oxidase assay. Serum cholesterol (CHOL), serum triglycerides (TG), serum HDL cholesterol (HDL-C) and serum LDL cholesterol (LDL-C) were determined by full automatic biochemical instrument. Fasting insulin was measured by enzyme immunoassay to calculate insulin resistance index (IRI). Height, weight, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured to calculate body mass index (BMI) and body fat percentage (BF %). Resistin protein expression in pregnant women placental tissue (67 905 +/- 8441) (arbitrary A values) was much higher than that in subcutaneous adipose tissue in pregnant women abdomen (40 718 +/- 3818, P < 0.01), non-pregnant women abdomen (38 288 +/- 2084, P < 0.01), normal human abdomen (39 421 +/- 6087, P < 0.01) and thigh (14 942 +/- 6706, P < 0.001) respectively. The resistin expression in abdominal subcutaneous adipose tissue showed no significant difference among pregnant, non-pregnant women and normal human, but much higher than that in thigh subcutaneous adipose tissue (P < 0.001). Pearson analysis revealed that resistin protein was correlated with BMI (r = 0.42), fasting insulin concentration (r = 0.38), IRI (r = 0.34), BF % (r = 0.43) and fasting glucose (r = 0.39), but not with blood pressure, CHOL, TG, HDL-C and LDL-C. It was suggested that resistin protein expression in human abdominal subcutaneous adipose tissue was much higher than that in human thigh subcutaneous adipose tissue. Resistin was closely related with central obesity, leading to IR, subsequently obesity and T2DM. Resistin protein expression in placental tissue was much higher than that in subcutaneous adipose tissue in normal human abdomen, pregnant abdomen, non-pregnant women abdomen and thigh. It was indicated that resistin protein could be secreted from human placental tissue. Resistin might be one of the factors that lead to pregnant physiological IR and GDM.

Blood Glucose↗

The influence of the Pro12Ala mutation of PPARgamma2 receptor gene on beta-cells restoration and insulin resistance in type 2 diabetes with hypertension.

The aim of this investigation was to determine whether a PPARgamma2 Pro12Ala polymorphism was associated with insulin resistance, beta-cell function and hypertension in Chinese populations. 289 unrelated Chinese subjects first diagnosed Type 2 diabetes (HbAC1 < 6.0) were investigated, including 132 hypertensive diabetic (HTD) subjects, 157 normotensive diabetic (NTD) subjects. Blood pressure and anthropometric measurements were collected from all participants, as well as several venous blood samples during oral glucose tolerance test (OGTT). Biochemical measurements (high-density lipoprotein (HDL) and low-density lipoprotein-cholesterol (LDL), triglycerides) and PPARgamma2 Pro12Ala genotype were also determined. And insulin resistance and beta-cells function was assessed by HOMA-IR and HOMA-beta respectively. The frequency of subjects bearing the Pro12Ala was lower in the hypertension group (3.03%) than in the non-hypertension group (5.7%) (P < 0.05) after adjusted for age, BMI and gender. Hypertensive diabetic Pro12Ala subjects had lower fasting plasma glucose level (P = 0.0127), and better glucose tolerance 60 min after oral glucose (P = 0.0361). Moreover, plasma insulin concentrations at 60 min was lower than those without A variant (P = 0.0275), and both hypertensive Ala/Pro in HOMA-beta (P = 0.0455) and AUC for insulin (P = 0.0473) were higher, and HOMA-IR was lower (P = 0.0375) as compared with hypertensive Pro/Pro subjects. No association was observed between Pro12Ala genotype and BMI, total cholesterol, HDL- cholesterol or triglycerides in either group. Our findings suggested that the Ala 12 allele of the PPARgamma2 gene may improve insulin resistance and ameliorate beta-cell function reserves in T2DM with hypertension, and protect patients from hypertension in T2DM. As an important thrifty gene, environment factors may exerts an effect of PPAR gamma2 on glucose homeostasis and insulin resistance.

Alanine↗

[Future targets in the treatment of type 2 diabetes].

Prevention and treatment of type 2 diabetes mellitus (T2DM) and the metabolic syndrome represent a major clinical challenge, because effective strategies such as fat restriction and exercise are difficult to implement into diabetes treatment. Based on the increasing knowledge on the pathogenesis of T2DM, new therapeutic approaches are currently under investigation. Potential targets of new therapeutic approaches include: (i) Inhibition of hepatic glucose production, (ii) stimulation of glucose-dependent insulin secretion, (iii) enhancement of insulin signal transduction, and (iv) reduction of body fat mass. Agonists of glucagon-like-peptide 1 (GLP-1) and antagonists of dipeptidylpeptidase IV, which inactivates GLP-1, stimulate glucose-dependent insulin secretion, improve hyperglycemia and are already tested in clinical trials. In humans, glucagon antagonists and an amylin analogue reduce glucagon-dependent glucose production. The glucose-lowering effect of current modulators of lipid oxidation is not pronounced and their use could be limited by side effects. In addition to clinically approved thiazolidendiones, new agonists of the peroxisome proliferator activator receptor gamma (PPAR gamma) as well as combined PPAR alpha/gamma agonists are developed at present. The direct modulation of insulin signal transduction is still limited to experimental studies.

Animals↗

Eating behavior affects quality of life in type 2 diabetes mellitus.

We evaluated the prevalence of disordered eating behavior in 168 unselected outpatients with type 2 diabetes mellitus (T2DM) and the effects on the health related quality of life (HRQL). Subjects in generally good glycemic control, treated by diet or oral hypoglycemic agents (58% M; 63.8+/-SD 10.1 years; BMI, 29.7+/-5.9 kg/m2) completed self-administered questionnaires for HRQL (SF-36) and eating behavior [(Three-Factor Eating Questionnaire (TFEQ); Binge Eating Scale (BES)]. Data on HRQL were computed as effectsizes in comparison to population norm. The prevalence of altered TFEQ scales was not different between genders, and varied between 22.1% (disinhibition) and 41.4% (restriction), but only 6.7% had a positive BES score. Age (OR, 0.58 for decade; 95% CI, 0.39-0.87), duration of diabetes (OR, 1.33 for 5 years; 1.01-1.74) and BMI (OR, 1.11; 1.04-1.18) were predictive for the presence of disinhibition. BMI also predicted hunger (OR, 1.16; 1.08-1.25). SF36 domains were not different in relation to positive BES. Disinhibition at TFEQ was significantly associated with poor social functioning (p=0.018) and role-emotional (p=0.022), whereas hunger was associated with poor physical functioning (p=0.010), role-physical (p=0.0014), social functioning (p=0.015) and role-emotional (p=0.0001). Metabolic control, duration of diabetes, and the presence of complications were not associated with HRQL. A disordered eating behavior may be present in T2DM patients, and is associated with poor HRQL. This condition must be considered for an olistic approach to weight control.

Aged↗

Phlorizin treatment prevents the decrease in plasma insulin levels but not the progressive histopathological changes in the pancreatic islets during aging of Zucker diabetic fatty rats.

A hallmark of Type 2 diabetes mellitus (T2DM) is chronic hyperglycemia, which is thought to play a role in pancreatic beta-cell failure. Here we investigated whether treatment of Zucker diabetic fatty (ZDF) rats, an animal model for T2DM, with the renal glucose transport inhibitor phlorizin could prevent alterations in the pancreatic islets. ZDF rats were treated with phlorizin or vehicle for 13 weeks starting with 6-week-old rats and before the onset of hyperglycemia. During the treatment, blood glucose levels in sham-treated ZDF rats increased rapidly from 7.7 +/- 0.3 to 24.8 +/- 0.6 mmol/l, whereas those in phlorizin-treated ZDF rats increased only slightly, but significantly, from 7.0 +/- 0.2 to 8.9 +/- 0.6 mmol/l. Phlorizin prevented the decrease in plasma insulin levels and caused a higher increase in body weight of the ZDF rats. Compared to 6-week-old untreated ZDF rats, in 19-week-old sham- and phlorizin-treated ZDF rats similar changes were found in islet architecture (more irregular boundaries and a disrupted mantle of peripheral islet cells) and in the mitochondria at the ultrastructural level (swelling of the matrix and disruption of the cristae). Using reverse transcriptase-polymerase chain reaction, no differences in mRNA expression levels were found for insulin, islet amyloid polypeptide (IAPP), and the prohormone convertase (PC) 1 and PC2 between 6-week-old untreated ZDF rats and 19-week-old sham- and phlorizin-treated ZDF rats. However, immunohistochemistry revealed similar decreases in insulin and IAPP protein expression in 19-week-old sham- and phlorizin-treated ZDF rats compared to those in 6-week-old untreated ZDF rats. These observations indicate that during aging of ZDF rats phlorizin treatment does not prevent the decreases in insulin and IAPP protein expression and the progressive histopathological changes in the pancreatic islets. Therefore, it is highly unlikely that these changes are caused by chronic hyperglycemia.

Aging↗

Beta-cell dysfunction and glucose intolerance: results from the San Antonio metabolism (SAM) study.

AIMS/HYPOTHESIS: Both insulin resistance and beta-cell dysfunction play a role in the transition from normal glucose tolerance (NGT) to Type 2 diabetes (T2DM) through impaired glucose tolerance (IGT). The aim of the study was to define the level of glycaemia at which beta-cell dysfunction becomes evident in the context of existing insulin resistance. METHODS: Insulin response (OGTT) and insulin sensitivity (euglycaemic insulin clamp) were evaluated in 388 subjects in the San Antonio Metabolism (SAM) study (138 NGT, 49 IGT and 201 T2DM). In all subjects the insulin secretion/insulin resistance index (DeltaI/DeltaG/IR) was calculated as the ratio of the increment in plasma insulin to the increment in plasma glucose during the OGTT divided by insulin resistance, as measured during the clamp. RESULTS: In lean NGTs with a 2-h plasma glucose concentration (2-h PG) between 5.6 and 6.6 and between 6.7 and 7.7 mmol/l, there was a progressive decline in DeltaI/DeltaG/IR compared with NGTs with a 2-h PG less than 5.6 mmol/l. There was a further decline in DeltaI/DeltaG/IR in IGTs with a 2-h PG between 7.8 and 9.3 and between 9.4 and 11.0 mmol/l, and in Type 2 diabetic patients with a 2-h PG greater than 11.1 mmol/l. Lean and obese subjects showed coincident patterns of relation of 2-h PG to DeltaI/DeltaG/IR. CONCLUSION/INTERPRETATION: When the plasma insulin response to oral glucose is related to the glycaemic stimulus and severity of insulin resistance, there is a progressive decline in beta-cell function that begins in "normal" glucose tolerant individuals.

Adult↗

Estimation of single nucleotide polymorphism allele frequency in DNA pools by using Pyrosequencing.

Positional cloning of genes underlying complex diseases, such as type 2 diabetes mellitus (T2DM), typically follows a two-tiered process in which a chromosomal region is first identified by genome-wide linkage scanning, followed by association analyses using densely spaced single nucleotide polymorphic markers to identify the causal variant(s). The success of genome-wide single nucleotide polymorphism (SNP) detection has resulted in a vast number of potential markers available for use in the construction of such dense SNP maps. However, the cost of genotyping large numbers of SNPs in appropriately sized samples is nearly prohibitive. We have explored pooled DNA genotyping as a means of identifying differences in allele frequency between pools of individuals with T2DM and unaffected controls by using Pyrosequencing technology. We found that allele frequencies in pooled DNA were strongly correlated with those in individuals (r=0.99, P<0.0001) across a wide range of allele frequencies (0.02-0.50). We further investigated the sensitivity of this method to detect allele frequency differences between contrived pools, also over a wide range of allele frequencies. We found that Pyrosequencing was able to detect an allele frequency difference of less than 2% between pools, indicating that this method may be sensitive enough for use in association studies involving complex diseases where a small difference in allele frequency between cases and controls is expected.

Base Sequence↗

The -822G/A polymorphism in the promoter region of the MAP4K5 gene is associated with reduced risk of type 2 diabetes in Chinese Hans from Shanghai.

MAP4K5 (mitogen-activated protein kinase kinase kinase kinase 5), an early component of MAP kinase signal cascades was shown to activate Jun kinase in mammalian cells. The association between SNPs of MAP4K5 and type 2 diabetes (T2DM) was investigated due to the known relationship of the JNK pathway with T2DM. A total of 1,399 cases were included in the study. Oral glucose tolerance test (OGTT) and insulin release test (IRT) were performed, and blood DNA samples were extracted and genotyped on the MAP4K5 -822G/A site. These cases were subdivided into central-obesity and nonobesity groups, based upon their individual waist circumference. Allele-specific real-time PCR was employed for genotyping. No difference was found between the two groups in the distribution of three genotypes on MAP4K5 -822G/A. In the central-obesity group, fewer diabetic patients (38.9%) were present in the AA genotype group than the GG/GA group (58.5%, P=0.024). Glucose levels after 30 and 60 min of 75 g glucose tolerance, area under the curve for glucose, and insulin secretion indexes were lower (P<0.05) in AA than those in GG/GA genotype group in the central-obesity cases. Other variables did not show significant differences between the two groups. In the Han population from Shanghai, the AA genotype of MAP4K5 -822G/A in central-obesity cases appears less likely to develop diabetes compared with the other genotypes. Therefore, the G allele may be a factor that does not protect central-obesity cases from developing into diabetes.

Adult↗

Quality of life, health status and clinical outcomes in Type 2 diabetes patients.

This study examines relationships between patient reported outcomes (PROs) and clinical outcomes in Type 2 diabetes mellitus (T2DM). Patients at the outpatient clinics of a university hospital completed measures of generic health status (SF-12), diabetes-specific quality of life (Audit of Diabetes Dependent Quality of Life - ADDQoL), and depressive symptoms (Center for Epidemiologic Studies Depression - CES-D). Patient reported data were merged with a retrospective collection of clinical and utilization data, including HbA1C, from electronic medical records. A Charlson comorbidity score, diabetes complications score, BMI, and total number of ER and hospital visits were calculated. Usable response rate was 44.3% (n = 385). Patients were dichotomized into glycemic control levels based on the ADA recommended A1C level < 7.0, vs. >or= 7.0. The ADDQoL, PCS-12, and MCS-12 scores were separately examined as dependent variables using hierarchical regression models, with glycemic control as the primary explanatory variable, and controlling for demographics and clinical variables including comorbidities and complications. Glycemic control was not a significant predictor in any regression model. Obesity was a significant predictor leading to poorer PCS-12 and MCS-12 scores, while depressive symptoms significantly resulted in lower PCS-12, MCS-12 and ADDQoL scores. These and other factors related to self-management behaviors may contribute to a greater understanding of how to intervene with patients with T2DM. The use of such PROs alongside biomedical measures such as A1C is recommended.

Aged↗

Oxidative stress: changes in pregnancy and with gestational diabetes mellitus.

Pregnancy is susceptible to oxidative stress and antioxidant defenses can be altered in response to elevated levels of oxidative stress. Limited data in gestational diabetes mellitus (GDM) suggest that products of lipid peroxidation may be increased and antioxidant enzyme activities decreased, although the results have been inconsistent. As in type 2 diabetes mellitus (T2DM), glycemic levels in patients with GDM correlate with concentrations of lipid peroxides. The effects of supplementation with antioxidants or antioxidant-rich food in T2DM are controversial. Whether or not increased antioxidant intake can reduce the complications of GDM in both mother and fetus has not been explored.

Antioxidants↗

Fatty acid-induced inflammation and insulin resistance in skeletal muscle and liver.

Plasma free fatty acid (FFA) levels are elevated in obesity. FFA, by causing insulin resistance in muscle, liver, and endothelial cells, contributes to the development of type 2 diabetes mellitus (T2DM), hypertension, dyslipidemia, and nonalcoholic fatty liver disease (NAFLD). The mechanism through which FFA induces insulin resistance involves intramyocellular and intrahepatocellular accumulation of triglycerides and diacylglycerol, activation of several serine/threonine kinases, reduction in tyrosine phosphorylation of the insulin receptor substrate (IRS)-1/2, and impairment of the IRS/phosphatidylinositol 3-kinase pathway of insulin signaling. FFA also produces low-grade inflammation in skeletal muscle and liver through activation of nuclear factor-kappaB, resulting in release of several proinflammatory and proatherogenic cytokines. Thus, elevated FFA levels (due to obesity or to high-fat feeding) cause insulin resistance in skeletal muscle and liver, which contributes to the development of T2DM, and produce low-grade inflammation, which contributes to the development of atherosclerotic vascular diseases and NAFLD.

Diabetes Mellitus, Type 2↗

Role of impaired insulin secretion and insulin resistance in the pathogenesis of type 2 diabetes mellitus.

Type 2 diabetes mellitus (T2DM) is a heterogeneous disorder caused by a combination of genetic and acquired abnormalities that affect insulin sensitivity and insulin secretion. Currently available data suggest that insulin resistance is the acquired defect largely secondary to unhealthy lifestyles and that the major genetic factor is impaired insulin secretion. The latter is the result of both reduced beta-cell mass and functional abnormalities makes the beta-cell unable to compensate for increased insulin requirements caused by insulin resistance. Targeting both insulin resistance and impaired insulin secretion is therefore appropriate to prevent T2DM and to improve glycemic control in those with the disorder.

Diabetes Mellitus, Type 2↗

The relationship between C-reactive protein and subclinical cardiovascular disease in the Diabetes Heart Study (DHS).

BACKGROUND: Epidemiological studies suggest that levels of C-reactive protein (CRP) predict cardiovascular disease (CVD). We have evaluated the relationship between CRP and subclinical CVD in a study cohort at high risk of CVD. METHODS: The DHS is a single-center, family-based study of the genetic and environmental components of CVD in type 2 diabetes mellitus (T2DM). We evaluated 666 subjects (551 T2DM affected and 115 unaffected) with an average age of 61 years. Measures of coronary artery calcium (CAC), intimal-medial thickness (IMT) of the common carotid artery, and CRP were obtained on all subjects. RESULTS: C-reactive protein is positively and significantly associated with female sex, body mass index, and smoking and is negatively and significantly associated with age and statin use. Generalized estimating equations were used to test whether CRP was associated with each subclinical CVD measure (presence/absence of CAC, quantity of CAC, and IMT) adjusting for covariates and correlation among siblings. Stratified analyses were conducted to examine whether these associations differed across sex and statin use. In the overall analysis, CRP was not significantly associated with IMT or presence of CAC but was negatively and significantly associated with quantity of CAC (P = .01). When covariates were added, the relationship was no longer significant. Similar patterns were observed in stratified analyses based on sex, statin use, and diabetes status: weak but negative association of CAC with CRP, which became nonsignificant with adjustment for covariates. CONCLUSIONS: In a population at high risk for CVD, there was no evidence of incremental association of CRP levels with measures of subclinical CVD.

C-Reactive Protein↗

Regulation of plasma triglycerides in insulin resistance and diabetes.

Increased plasma levels of triglycerides (TG) in very low density lipoproteins (VLDL) are not only common characteristics of the dyslipidemia associated with insulin resistance and type 2 diabetes mellitus (T2DM) but are the central pathophysiologic feature of the abnormal lipid profile. Overproduction of VLDL leads to increased plasma levels of TG which, via an exchange process mediated by cholesterol ester transfer protein (CETP), results in low levels of high density lipoprotein (HDL) cholesterol and apolipoprotein A-I, and the generation of small, dense, cholesterol ester depleted low density lipoproteins (LDL). Increased assembly and secretion of VLDL by the liver results from the complex, post-transcriptional regulation of apolipoprotein B (apoB) metabolism in the liver. In the presence of low levels of hepatic TG and cholesterol, much of the constitutively synthesized apoB is degraded by both proteasomal and non-proteasomal pathways. When excess TG, and to a lesser extent, cholesterol, are present, and in the presence of active microsomal triglycerides transfer protein, apoB is targeted for secretion. The major sources of TG in the liver: uptake of fatty acids (FA) released by lipolysis of adipose tissue TG, uptake of TGFA in VLDL and chylomicrons remnants, and hepatic de novo lipogenesis (the synthesis of FA from glucose) are all abnormally increased in insulin resistance. Treatment of the dyslipidemia in insulin resistant individuals and patients with T2DM has been successful in reducing cardiovascular disease; LDL cholesterol, TG, and HDL cholesterol are all appropriate targets for therapy when diet, exercise, and weight loss do not achieve goals.

Adipose Tissue↗