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PubMed2006

Skeletal muscle protein anabolic response to increased energy and insulin is preserved in poorly controlled type 2 diabetes.

Type 2 diabetes (T2DM) subjects failing diet treatment are characterized by hyperinsulinemia and insulin resistance leading to fasting and postprandial hyperglycemia and hyperlipidemia. Energy is essential for allowing the process of protein synthesis to proceed. Additionally, insulin can stimulate protein synthesis in human muscle. The aims of this study were to determine if poorly controlled T2DM affects postabsorptive muscle protein anabolism, and if the muscle anabolic response to hyperinsulinemia with high energy availability is maintained. Control (n = 6) and T2DM subjects (n = 6) were studied in the postabsorptive state and during an isoenergetic high nutritional energy clamp (relative to postabsorptive state). Muscle protein synthesis and breakdown (nmol . min(-1) . 100 g leg muscle(-1)) were assessed using stable isotope methodology, femoral arterio-venous sampling, muscle biopsies, and a three-pool model to calculate protein turnover. Postabsorptive phenylalanine net balance and whole body rate of appearance (Ra) were not different between groups; however, basal muscle protein breakdown was higher in T2DM (94 +/- 9) than in controls (58 +/- 12) (P < 0.05) and muscle protein synthesis tended (P = 0.07) to be elevated in T2DM (66 +/- 14) compared with controls (39 +/- 6). During the clamp, net balance increased, whole body Ra and muscle protein breakdown decreased (P < 0.05), and muscle protein synthesis tended to decrease (P = 0.08) to a similar extent in both groups. We conclude that postabsorptive muscle protein turnover is elevated in poorly controlled T2DM, however, there is no excessive loss of muscle protein because net balance is not different from controls. Moreover, the anabolic response to increased insulin and energy availability is maintained in T2DM.

Adipose Tissue↗

PubMed2006

Prevalence and characteristics of impaired glucose metabolism in patients referred to comprehensive cardiac rehabilitation: the DANSUK study.

BACKGROUND: Lifestyle and pharmacological interventions can delay the progression of impaired glucose tolerance (IGT) to type 2 diabetes (T2DM), and there is growing evidence that earlier detection of T2DM and intensified risk factor management may result in improved cardiovascular morbidity and mortality. We studied the prevalence of impaired glucose metabolism (T2DM, IGT and impaired fasting glucose; IFG) in patients referred to cardiac rehabilitation, and further studied whether we could identify groups in which an oral glucose tolerance test (OGTT) need not be performed. METHODS: As part of a cardiac rehabilitation trial, 201 patients participated. Patients without a diagnosis of T2DM (N=159) underwent an OGTT 3 months after inclusion. RESULTS: Forty-two patients (21%) had known T2DM at enrolment. Based on the OGTT, 26 patients (13%) had unrecognized T2DM, 36 (18%) had IGT and 19 (9%) were diagnosed with isolated IFG according to the World Health Organization definition. Using fasting plasma glucose alone, 19% of the patients with unrecognized T2DM and two-thirds of patients with IGT would be misclassified. Using IFG as a means to detect IGT showed a sensitivity of only 33% and a positive predictive value of 39%. CONCLUSION: More than 60% of the patients (123/201) referred to cardiac rehabilitation had impaired glucose metabolism and 18% of the screened patients (29/159) would be misclassified if an OGTT was omitted. IFG and IGT did not identify the same patients or the same cardiovascular risk profile. An OGTT test should therefore be considered a constituent part of routine care management in cardiac rehabilitation settings.

Aged↗

PubMed2004

Presentation and course of Type 2 diabetes in youth in a large multi-ethnic city.

AIM: To review the clinical experience of children and teens diagnosed with Type 2 diabetes (T2DM) at a paediatric hospital serving a large urban multi-ethnic population. METHODS: Retrospective chart review of patients with T2DM followed in the diabetes clinic at the Hospital for Sick Children (HSC) over an 8-year period. Patients who were included were younger than 18, referred at the onset of diabetes, and where presentation and/or clinical course was 'typical' of T2DM. RESULTS: Of 1020 children with diabetes followed at HSC, 4% were identified as having T2DM in 2002. There was a sixfold increase in new cases from 1994 to 2002. The mean age at diagnosis was 13.5 +/- 2.2 years (range 8.8-17.5) with a female-to-male ratio of 1.7. Most had a first- or second-degree relative with T2DM. There was an overrepresentation of children with T2DM from Asian and African Canadian ethnic groups relative to the regional population. The majority of teens were asymptomatic at presentation, with a smaller number in diabetic ketoacidosis (DKA) at diagnosis. Mean HbA1c at diagnosis was 10 +/- 3.4%. Approximately one half of patients were initially treated by diet and exercise with many requiring intensification of therapy over a short period of time. CONCLUSIONS: We report a similar increase in T2DM incidence and clinical presentation at HSC to other clinic reports in large North American urban centres. Of note is the high prevalence of children of South/South-East Asian descent.

Adolescent↗

PubMed2005

5'AMP activated protein kinase expression in human skeletal muscle: effects of strength training and type 2 diabetes.

Strength training enhances insulin sensitivity and represents an alternative to endurance training for patients with type 2 diabetes (T2DM). The 5'AMP-activated protein kinase (AMPK) may mediate adaptations in skeletal muscle in response to exercise training; however, little is known about adaptations within the AMPK system itself. We investigated the effect of strength training and T2DM on the isoform expression and the heterotrimeric composition of the AMPK in human skeletal muscle. Ten patients with T2DM and seven healthy subjects strength trained (T) one leg for 6 weeks, while the other leg remained untrained (UT). Muscle biopsies were obtained before and after the training period. Basal AMPK activity and protein/mRNA expression of both catalytic (alpha1 and alpha2) and regulatory (beta1, beta2, gamma1, gamma2a, gamma2b and gamma3) AMPK isoforms were independent of T2DM, whereas the protein content of alpha1 (+16%), beta2 (+14%) and gamma1 (+29%) was higher and the gamma3 content was lower (-48%) in trained compared with untrained muscle (all P < 0.01). The majority of alpha protein co-immunoprecipitated with beta2 and alpha2/beta2 accounted for the majority of these complexes. gamma3 was only associated with alpha2 and beta2 subunits, and accounted for approximately 20% of all alpha2/beta2 complexes. The remaining alpha2/beta2 and the alpha1/beta2 complexes were associated with gamma1. The trimer composition was unaffected by T2DM, whereas training induced a shift from gamma3- to gamma1-containing trimers. The data question muscular AMPK as a primary cause of T2DM whereas the maintained function in patients with T2DM makes muscular AMPK an obvious therapeutic target. In human skeletal muscle only three of 12 possible AMPK trimer combinations exist, and the expression of the subunit isoforms is susceptible to moderate strength training, which may influence metabolism and improve energy homeostasis in trained muscle.

AMP-Activated Protein Kinases↗

PubMed2004

Muscle glycogen content in type 2 diabetes mellitus.

Muscle contains the largest reservoir of glycogen (Glyc), a depot that is closely regulated and with influence on insulin sensitivity. The current study examines muscle Glyc in type 2 diabetes mellitus (T2DM) and obesity and with respect to muscle fiber type, intramyocellular lipid content (IMCL), and mitochondrial function (oxidative enzyme activity; OX-Enz). There is increasing interest in the relation of IMCL and mitochondrial dysfunction with insulin resistance (IR), yet the association with muscle Glyc has not been examined with regard to these parameters. Using a quantitative histological approach specific to muscle fiber types, we assessed muscle Glyc, IMCL, and OX-Enz in vastus lateralis obtained by percutaneous biopsy in lean nondiabetic (L; n = 16), obese nondiabetic (Ob; n = 15), and T2DM volunteers (n = 14). Insulin sensitivity was estimated using homeostasis model assessment (HOMA)-IR. Muscle Glyc was reduced in T2DM, a deficit evident for type IIa fibers, yet minor in types I and IIb fibers. Low Glyc in T2DM correlated with fasting hyperglycemia. Also, in T2DM and Ob, there was significantly higher IMCL and lower OX-Enz in all fiber types. The IMCL-to-OX-Enz ratio, especially for type I fibers, correlated strongly with IR. Similarly, a Glyc-to-OX-Enz ratio correlated with IR, particularly for type IIb fibers. This ratio tended to be higher in Ob and T2DM. In summary, there is decreased muscle Glyc in T2DM yet a disproportional Glyc-to-OX-Enz relationship that is related to IR, although not as robustly as the IMCL-to-OX-Enz ratio.

Diabetes Mellitus, Type 2↗

PubMed2001

Gluconeogenesis in moderately and severely hyperglycemic patients with type 2 diabetes mellitus.

We tested the generally accepted concept that increased gluconeogenesis (GNG) and endogenous glucose production (EGP) are the main reasons for postabsorptive hyperglycemia in patients with type 2 diabetes mellitus (T2DM). GNG was measured with the (2)H(2)O method by use of both the C5-to-C2 ratio (C5/C2, with gas chromatography-mass spectrometry) and the C5-to-(2)H(2)O ratio (C5/(2)H(2)O, with isotope ratio mass spectrometry), and EGP was measured with 3-[(3)H]glucose in 27 patients with T2DM [13 with fasting plasma glucose (FPG) >10 mM and 14 with FPG <10 mM] and in 7 weight- and age-matched nondiabetic controls. The results showed 1) that GNG could be determined accurately with (2)H(2)O by using either C5/C2 or C5/(2)H(2)O; 2) that whereas after an overnight fast of 16 h, GNG was higher in the entire group of patients with T2DM than in controls (6.4 vs. 5.0 micromol. kg(-1). min(-1) or 60.4 vs. 51.4% of EGP, P < 0.02), GNG was within normal limits (less than the mean +/- 2 SD of controls or <65.3%) in 11/14 (79%) patients with mild to moderate hyperglycemia (FPG <10 mM) and in 5/13 (38%) of patients with severe hyperglycemia (FPG 10-20 mM); 3) that elevated GNG in T2DM was associated with a 43% decrease in prehepatic insulin secretion, i.e., with hepatic insulin deficiency; and 4) that FPG correlated significantly with glucose clearance (insulin resistance) (r = 0.70) and with GNG (r = 0.50) or EGP (r = 0.45). We conclude 1) that peripheral insulin resistance is at least as important as GNG (and EGP) as a cause of postabsorptive hyperglycemia in T2DM and 2) that GNG and EGP in T2DM are increased under conditions of significant hepatic insulin deficiency and thus probably represent a late event in the course of T2DM.

Aged↗

PubMed2006

Subsets of Finns with high HDL to total cholesterol ratio show evidence for linkage to type 2 diabetes on chromosome 6q.

OBJECTIVES: The purpose of this study was to examine carefully heterogeneity underlying evidence for linkage to type 2 diabetes (T2DM) on chromosome 6q from two sets of FUSION families. METHODS: Ordered subsets analysis (OSA) was performed on two sets of FUSION families. For OSA results showing significant improvement in evidence for linkage, T2DM-related phenotypes were compared between individuals with T2DM within the subset versus the complement. RESULTS: OSA analysis revealed 105 families with the highest average HDL to total cholesterol ratio (HDL ratio) that had strongly increased evidence for linkage (MLS = 7.91 at 78.0 cM; uncorrected p = 0.00002). Subjects with T2DM within this subset were significantly leaner, had lower fasting glucose, insulin, and C-peptide, and more favorable cardiovascular risk profile compared to the complement set of subjects with T2DM. OSA also revealed 33 families with the lowest average fasting insulin that had increased evidence for linkage at a second locus (MLS = 3.45 at 128 cM; uncorrected p = 0.017) coincident with quantitative trait locus linkage analysis results for fasting and 2-hour insulin in subjects without T2DM. CONCLUSIONS: These results suggest two diabetes susceptibility loci on chromosome 6q that may affect subsets of individuals with a milder form of T2DM.

Aged↗

PubMed2006

The use of proteomics in identifying differentially expressed serum proteins in humans with type 2 diabetes.

BACKGROUND: The aim of the study was to optimize protocols for finding and identifying serum proteins that are differentially expressed in persons with normal glucose tolerance (NGT) compared to individuals with type 2 diabetes mellitus (T2DM). Serum from persons with NGT and persons with T2DM was profiled using ProteinChip arrays and time-of-flight mass spectra were generated by surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS). RESULTS: Mass spectra from NGT- and T2DM-groups were compared. Fifteen proteins ranging from 5 to 79 kDa were differentially expressed (p < 0.05). Five of these proteins showed decreased and ten showed increased serum levels in individuals with T2DM. To be able to identify the proteins, the complexity of the sample was reduced by fractionation approaches. Subsequently, the purified fractions containing biomarkers were separated by one-dimensional SDS-polyacrylamide gel electrophoresis (SDS-PAGE) in two identical lanes. Protein bands of the first lane were excised and subjected to passive elution to recapture the biomarkers on ProteinChip arrays. The corresponding bands of the second lane were subjected to peptide-mass fingerprinting (PMF). Using this approach four of the differentially expressed proteins were identified as apolipoprotein C3 (9.4 kDa), transthyretin (13.9 kDa), albumin (66 kDa) and transferrin (79 kDa). Whereas apolipoprotein C3 and transthyretin were up-regulated, albumin and transferrin were down-regulated in T2DM. CONCLUSION: Protocols for protein profiling by SELDI-TOF MS and protein identification by fractionation, SDS-PAGE and PMF were optimized for serum from humans with T2DM. With these protocols differentially expressed proteins were discovered and identified when serum from NGT- and T2DM-individuals was analyzed.

Journal Article↗

PubMed2003

Oral L-arginine and vitamins E and C improve endothelial function in women with type 2 diabetes.

Endothelial dilator function is impaired in people with type 2 diabetes mellitus (T2DM). Prior research indicates that this can be improved with intravenous administration of ascorbate or L-arginine, but whether these agents have this effect when administered by the clinically practical oral route is unknown. To investigate this question, 10 premenopausal women with T2DM and 10 healthy, premenopausal, non-diabetic women received, in random sequence, a 1-week administration of oral L-arginine (9 g daily) or vitamins E (1800 mg) and C (1000 mg) with an intervening 1-week washout period. Flow-mediated brachial artery dilation (FMD) was measured by ultrasonography and forearm blood flow was measured by plethysmography before and following blood pressure cuff-induced forearm ischemia before and after each week of treatment. At baseline, the women with T2DM had lesser FMD responses (0.028 +/- 0.006 cm vs 0.056 +/- 0.008 cm, p < 0.05). Post-ischemic forearm hyperemia was reduced at baseline in T2DM compared with controls (16.4 +/- 1.8 vs 26.0 +/- 1.4 ml 100 ml(-1) min(-1), p < 0.05). Administration of L-arginine caused a 50 +/- 12% increase in FMD in T2DM (p < 0.05) and raised post-ischemic forearm blood flow by 29 +/- 8% (p < 0.05). No significant changes were seen in controls. Administration of vitamins E and C in women with T2DM produced an increase in the brachial artery diameter response of 79 +/- 15% (p < 0.05), but did not significantly increase the hyperemic blood flow response (p = NS). No significant changes in the responses of controls from pre to post vitamin administration were observed. We concluded that administration of two types of oral agents improved measures of endothelial function in people with T2DM.

Administration, Oral↗

PubMed2006

Calpains and their multiple roles in diabetes mellitus.

Type 2 diabetes mellitus (T2DM) can lead to death without treatment and it has been predicted that the condition will affect 215 million people worldwide by 2010. T2DM is a multifactorial disorder whose precise genetic causes and biochemical defects have not been fully elucidated, but at both levels, calpains appear to play a role. Positional cloning studies mapped T2DM susceptibility to CAPN10, the gene encoding the intracellular cysteine protease, calpain 10. Further studies have shown a number of noncoding polymorphisms in CAPN10 to be functionally associated with T2DM while the identification of coding polymorphisms, suggested that mutant calpain 10 proteins may also contribute to the disease. Here we review recent studies, which in addition to the latter enzyme, have linked calpain 5, calpain 3, and its splice variants, calpain 2 and calpain 1 to T2DM-related metabolic pathways along with T2DM-associated phenotypes, such as obesity and impaired insulin secretion, and T2DM-related complications, such as epithelial dysfunction and diabetic cataract.

Animals↗

PubMed2005

Elevated plasma level of visfatin/pre-B cell colony-enhancing factor in patients with type 2 diabetes mellitus.

CONTEXT: Visfatin (also known as pre-B cell colony-enhancing factor or PBEF) is a cytokine that is highly expressed in visceral fat and whose blood levels correlate with obesity. Originally isolated as a secreted factor that promotes the growth of B cell precursors and recently found to act as an insulin analog on the insulin receptor, its pathophysiological role in humans remains largely unknown. OBJECTIVES: In this study we investigated whether plasma visfatin level is altered in patients with type 2 diabetes mellitus (T2DM). DESIGN AND PATIENTS: Plasma visfatin as well as adiponectin and resistin concentrations were measured through ELISA in type 2 diabetic and nondiabetic subjects. RESULTS: A total of 61 patients with T2DM and 59 sex- and age-matched nondiabetic subjects were studied. Plasma visfatin was found to be elevated in patients with T2DM (31.9 +/- 31.7 vs. 15.8 +/- 16.7 ng/ml, P = 0.002). In contrast, adiponectin was decreased (4.3 +/- 2.5 vs. 30.8 +/- 10.3 microg/ml, P < 0.001), whereas plasma resistin level did not differ between the groups. Increasing concentrations of visfatin were independently and significantly associated with T2DM. Multiple logistic regression analysis revealed visfatin as an independent association factor for T2DM, even after full adjustment of known biomarkers. The association between adiponectin and T2DM was no longer significant after adjustments for body mass index or waist to hip ratio. In a multiple linear regression analysis, only waist to hip ratio was independently associated with plasma visfatin level. CONCLUSION: Our results indicate that visfatin may play a role in the pathogenesis of T2DM.

Adiponectin↗

PubMed2025

Meta-evolutionary exome analysis identifies novel type 2 diabetes mellitus genes in the UK Biobank and all of us.

Type 2 diabetes mellitus (T2DM) risk is heavily influenced by genetics, yet current association tests have explained only parts of its heritability. We developed MEVA (Meta-Evolutionary Action), a meta-analytic framework that integrates three complementary methods-EAML, Sigma-Diff, and GeneEMBED-to assess the functional burden of protein-coding variants using evolutionary data. MEVA was applied to exome data from 28,115 T2DM cases and 28,115 controls in the UK Biobank (UKB), identifying 101 genes (p < 1e-5). MEVA outperformed its component methods, each of which substantially outperformed a conventional burden test (MAGMA), in recovering known T2DM genes (AUROC = 0.925) and maintaining robustness in progressively smaller cohorts (AUROC = 0.917). MEVA showed significant enrichment for T2DM-related loci (p = 6.8e-10, p = 2.0e-34), protein interactions (z = 4.6, z = 4.2), pathways (p = 1.3e-6, z = 2.0), phenotypes (p = 1.3e-21, z = 9.1), and literature mentions (z = 7.2). Replication in 16,915 T2DM cases and 16,915 controls from All of Us (AoU) yielded 99 genes (p < 1e-5), 23 of which were also recovered in the UKB cohort - far exceeding random chance. These included established genes (SLC30A8, WFS1, HNF1A) and less-characterized candidates (NRIP1, ADAM30, CALCOCO2, TUBB1, ZFP36L2, WDR90). Notably, NRIP1 loss-of-function variants were associated with increased T2DM risk in both the UKB (OR = 1.09, FDR = 5.4e-4) and AoU (OR = 1.09, FDR = 0.046), and TUBB1 and CALCOCO2 gain-of-function variants showed consistent risk effects (FDR < 0.05). Pathway analyses revealed convergence on endoplasmic reticulum chaperone complexes (FDR = 0.02) and Hippo signaling (FDR = 8.5e-4). Finally, all 177 candidate genes were functionally prioritized using ten orthogonal criteria to guide experimental follow-up. These results demonstrate that combining complementary, impact-aware association tests increases sensitivity, improves replication, and expands the catalog of genetic risk factors for T2DM.

Humans↗

PubMed2006

Preventing type 2 diabetes in high risk patients: an overview of lifestyle and pharmacological measures.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is a common disease that is associated with an increased risk of vascular complications. The incidence of T2DM is also increasing. It follows that T2DM prevention is important. METHODS: Relevant articles (review articles, randomised studies and large cohort and case-control studies) were identified through a Medline search (up to March 2005). RESULTS: The first trials on T2DM prevention were based on lifestyle intervention. The results of these studies were impressive since they demonstrated that even a small reduction in weight could significantly reduce the incidence of T2DM. However, the main disadvantage of lifestyle measures is that they are difficult to achieve and sustain. Therefore, pharmacological interventions have also been evaluated. The results of trials using metformin, orlistat, nateglinide, acarbose, thiazolidinediones, hormone replacement therapy, statins or fibrates are either encouraging or require more extensive evaluation. In addition, studies using antihypertensive drugs (mainly angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists) showed that these drugs could also reduce the progression to T2DM in high risk individuals. CONCLUSIONS: T2DM has major quality of life and cost implications. Therefore, more research is needed to establish safe and cost effective ways to prevent this modern epidemic.

Anti-Obesity Agents↗

PubMed2006

Thiazolidinediones and progression of renal disease in patients with diabetes.

OBJECTIVE: Thiazolidinediones (TZDs) are used in the treatment of type 2 diabetes mellitus (T2DM) and appear to have beneficial effects on markers of cardiovascular or renal risk that are independent of glycemic control. We examined the effects of TZDs on renal survival in a predominantly black population with T2DM. METHODS: We performed a retrospective case-control study in patients with T2DM seen in our nephrology clinic in 2001 to 2002. Cases had T2DM and were on a TZD at presentation or for >or= 6 months over follow-up. Controls were matched for sex, age, duration of T2DM, and initial creatinine. Reaching end-stage renal disease (ESRD) was the primary end point. RESULTS: From 387 records, 43 cases (34 blacks, 31 females) and 106 controls (96 blacks, 83 females) were identified. The baseline characteristics were similar for both groups. Both groups had moderate renal disease (estimated glomerular filtration rate approximately 40-45 mL/min). Cases had lower systolic blood pressure over follow-up (p=.02), but there was no difference in glycemic control or use of insulin. Renal survival was better among cases (age- and gender-adjusted odds ratio for reaching ESRD 0.17 [95% confidence interval 0.03-0.8]; p=.03). When adjusted for systolic blood pressure over follow-up, the tendency for improved renal survival in cases remained but was no longer significant. CONCLUSION: We conclude that TZDs may protect against the progression of renal disease in T2DM. Prospective studies are required to determine the effects of TZDs on renal survival in T2DM.

Adult↗

PubMed2003

Reduced skeletal muscle oxygen uptake and reduced beta-cell function: two early abnormalities in normal glucose-tolerant offspring of patients with type 2 diabetes.

OBJECTIVE: Studies on insulin sensitivity and insulin secretion in subjects with a familial predisposition for type 2 diabetes mellitus (T2DM) traditionally produce inconsistent results. This may be due to small sample size, subject selection, matching procedures, and perhaps lack of a measure of physical fitness. RESEARCH DESIGN AND METHODS: In the present study, we specifically tested the hypothesis that a family history of T2DM is associated with reduced VO(2max), measured by incremental bicycle ergometry, independent of insulin sensitivity estimated from an oral glucose tolerance test (OGTT; n = 424) and measured by a euglycemic-hyperinsulinemic clamp (n = 185). Subjects included in the study were young (34 +/- 10 years), healthy, and normal glucose tolerant with either a first-degree relative (FDR) with T2DM (n = 183), a second-degree relative with T2DM (n = 94), or no family history of T2DM (control subjects, n = 147). BMI, percent body fat, waist-to-hip ratio (WHR), and habitual physical activity (HPA; standard questionnaire) were comparable among groups. FDRs had significantly lower VO(2max) than control subjects: 40.5 +/- 0.6 vs. 45.2 +/- 0.9 ml O(2)/kg lean body mass, P = 0.01 after adjusting for sex, age, BMI, HPA, and insulin sensitivity (euglycemic-hyperinsulinemic clamp). RESULTS: BMI, percent body fat, waist-to-hip ratio (WHR), and habitual physical activity (HPA; standard questionnaire) were comparable among groups. FDRs had significantly lower VO(2max) than control subjects: 40.5 +/- 0.6 vs. 45.2 +/- 0.9 ml O(2)/kg lean body mass, P = 0.01 after adjusting for sex, age, BMI, HPA, and insulin sensitivity (euglycemic-hyperinsulinemic clamp). Insulin sensitivity per se was not affected by family history of T2DM after adjusting for age, sex, BMI, and percent body fat (P = 0.76). The appropriateness of beta-cell function for the individual insulin sensitivity (disposition index: product of a validated secretion parameter [OGTT] and sensitivity [clamp]) was significantly lower in FDRs (87 +/- 4 units) versus control subjects (104 +/- 6 units, P = 0.02 after adjusting for sex, age, and BMI). Analyses of the larger OGTT group produced essentially the same results. CONCLUSIONS: In conclusion, these data are compatible with the hypothesis that familial predisposition for T2DM impairs maximal oxygen consumption in skeletal muscle. Because habitual physical activity was not different, genetic factors may be involved. Conceivably, reduced VO(2max) precedes skeletal muscle insulin resistance, providing a partial explanation for discrepancies in the literature.

Adult↗

PubMedDate not supplied

Microvascular abnormalities in the bulbar conjunctiva of patients with type 2 diabetes mellitus.

OBJECTIVE: To study and quantify microvascular abnormalities objectively in vivo in patients with type 2 diabetes mellitus (T2DM). METHODS: The conjunctival microcirculation in 14 patients with T2DM and in age-matched healthy control subjects without diabetes was videotaped and objectively studied by using computer-assisted intravital microscopy (CAIM), a novel and quantitative real-time technology. RESULTS: Patients with T2DM (N = 14) had significantly (P<0.01) wider conjunctival vessel diameters (71.9 +/- 5.2 mm) than did healthy nondiabetic control subjects (54.0 +/- 4.4 mm). In the study patients, microvascular distribution was significantly (P<0.01) abnormal (36.7 +/- 18.2 versus 45.3 +/- 9.6 cm per unit area, patients versus control subjects), and vessel distribution was uneven on the surface of the bulbar conjunctiva. The arteriole:venule (A:V) ratio in patients with T2DM was extremely variable and differed significantly (P<0.01) from that in the nondiabetic control subjects (A:V approximately 1:2). In addition, a unique sinusoidal (hypertensive) vascular pattern frequently existed in some of the large veins of all study patients with T2DM but in none of the nondiabetic control subjects. CONCLUSION: We identified the presence of microvascular changes (abnormalities) in the conjunctival microcirculation of patients with T2DM. Although all these abnormalities did not appear in the same patient at the same time, the sum total of their presence in each patient correlated significantly with disease severity, as noted in the medical records. The severity of microvascular abnormalities, however, did not correlate with the duration of the disease since diagnosis. CAIM may be a useful objective and quantitative technique for assessing microangiopathy in patients with T2DM. The easy noninvasive accessibility of the conjunctival vessels and the ability to identify and locate the same vessels repeatedly for longitudinal evaluations further emphasize the usefulness of this real-time technology.

Adult↗

PubMed2003

[A study of the degrees of insulin resistance and first-phase insulin secretion of beta-cells in metabolic syndrome patients with different glucose tolerance].

OBJECTIVE: To explore the insulin resistance and first-phase insulin secretion of beta-cells in normal persons, obese persons with normal glucose tolerance, obese persons with impaired glucose tolerance (IGT) and obese persons with type 2 diabetes (T2DM). METHODS: 75 g oral glucose tolerance test (OGTT) and Bergman's minimal model method of frequently sampled intravenous glucose tolerance test (FSIGTT) with reduced sample number (n = 12) were performed on a total of 151 subjects, 29 normal controls (control group), 44 obese persons with normal glucose tolerance (obesity group), 36 obese persons with IGT (IGT group), and 42 T2DMT patients (T2DM group) to determine the acute insulin response to glucose (AIRg), insulin sensitivity index (S(I)), and glucose effectiveness (S(G)). The disposition index (DI, AIRg X S(I)) was calculated to determine whether AIRg was adequate to compensate for insulin resistance. RESULTS: The S(I) value of the control group was significantly higher than those of the obesity, IGT, and T2DM groups (all P < 0.01), without significant difference among the latter three groups. The S(G) value of the control group was not significantly different from that of the obesity group, but significantly higher than those of the IGT and T2DM groups (both P < 0.01), without significant difference any 2 groups from the latter two groups. The AIRg of the normal group was similar to that of the IGT group (2.61 mU x L(-1) x min(-1) +/- 0.13 mU.L(-1) x min(-1) vs 2.56 mU x L(-1) x min(-1) +/- 0.25 mU x L(-1) x min(-1)), and significantly lower than that of the obesity group (3.02 mU x L(-1) x min(-1) +/- 0.27 mU x L(-1) x min(-1), P < 0.01) and higher than that of the T2DM group (1.54 mU x L(-1) x min(-1) +/- 0.55 mU x L(-1) x min(-1), P < 0.01). The value of DI was gradually decreased from the sequence of the groups of control, obesity, IGT, and T2DM (3.16 +/- 0.31, 2.65 +/- 0.50, 1.67 +/- 0.54), with significant differences between any two groups (all P < 0.01). Multiple regression analyses with S(I) and AIRg as dependent variables showed that S(I) was negatively correlated with BMI, 2 h glucose level in OGTT, 2 h insulin, triglyceride, and cholesterol (r(2) = 0.589, P < 0.001), and AIRg was positively correlated with BMI, S(G), fasting insulin, and 2 h insulin level and negatively correlated with 2 h glucose, and age (r(2) = 0.515, P < 0.001). CONCLUSION: Obese patients with different glucose tolerance have similar degrees of insulin resistance. Acute insulin response is increased in obesity group to compensate for the insulin resistance. Although the acute insulin response in the IGT group is similar to that in the control group, however, the compensation of islet beta cells in the IGT group is significantly decreased as compared with that in the obesity group, leading to glucose intolerance. There is a severe deficiency of acute insulin response to glucose in T2DM group.

Adult↗

PubMed2022

Insights on the pathogenesis of type 2 diabetes as revealed by signature genomic classifiers in an African American population in the Washington, DC area.

AIMS: African Americans (AA) in the United States have a high risk of type 2 diabetes mellitus (T2DM) and suffer from disparities in the prevalence, mortality, and comorbidities of the disease compared to other Americans. The present study aimed to shed light on the molecular mechanisms of disease pathogenesis of T2DM among AA in the Washington, DC region. METHODS: We performed TaqMan Low Density Arrays (TLDA) on 24 genes of interest that belong to three categories: metabolic disease and disorders, cancer-related genes, and neurobehavioural disorders genes. The 18 genes, viz. ARNT, CYP2D6, IL6, INSR, RRAD, SLC2A2 (metabolic disease and disorders), APC, BCL2, CSNK1D, MYC, SOD2, TP53 (Cancer-related), APBA1, APBB2, APOC1, APOE, GSK3B, and NAE1 (neurobehavioural disorders), were differentially expressed in T2DM participants compared to controls. RESULTS: Our results suggest that factors including gender, smoking habits, and the severity or lack of control of T2DM (as indicated by HbA1c levels) were significantly associated with differential gene expression. APBA1 was significantly (p-value <0.05) downregulated in all diabetes participants. Upregulation of APOE and CYP2D6 genes and downregulation of the INSR gene were observed in the majority of diabetes patients. CONCLUSIONS: Tobacco smoking and gender were significantly associated with case-control differences in expression of the APBA1 and APOE genes (connected with Alzheimer's disease) and the INSR and CYP2D6 (associated with metabolic disorders). The results highlight the need for more effective management of T2DM and for tobacco smoking cessation interventions in this community, and further research on the associations of T2DM with other disease processes, including cancer and neurobehavioral pathways.

Humans↗