Fatores associados ao controle metabólico em pacientes com diabetes melito tipo 2 não usuários de insulina

Introdução: a obtenção de um bom controle metabólico é essencial para a prevenção das complicações crônicas do Diabetes Melito (DM). O tratamento é complexo e depende da implementação efetiva das diferentes estratégias terapêuticas disponíveis. Para que isso seja possível, é necessário que o paciente entenda os princípios terapêuticos e consiga executá-los. A precária educação em diabetes é percebida como um dos obstáculos para o alcance das metas terapêuticas. Objetivo: analisar, os fatores associados ao controle metabólico, em pacientes com DM tipo 2 (DM2) não usuários de insulina. Métodos: foi realizado um estudo transversal em pacientes com DM2 não usuários de insulina, selecionados ao acaso entre aqueles que consultavam nos ambulatórios de Medicina Interna, Endocrinologia e Enfermagem do Hospital de Clínicas de Porto Alegre. Os pacientes foram submetidos à avaliação clínica, laboratorial e responderam um questionário que incluía o tipo de tratamento realizado para DM, outros medicamentos e co-morbidades, pesquisa de complicações em ano prévio e avaliação do conhecimento sobre DM. Os pacientes foram classificados em dois grupos, com bom ou mau controle glicêmico, de acordo com o valor da glico-hemoglobina de 1 ponto % acima do limite superior do método utilizado. As comparações entre variáveis contínuas, com distribuição normal, foram analisadas pelo teste t de Student para amostras não-pareadas e para as variáveis de distribuição assimétrica ou com variância heterogênea o teste U de Mann-Whitney. A comparação entre percentagem foi feita pelo teste de qui-quadrado ou exato de Fisher. Foi realizada uma análise logística múltipla para identificar os fatores mais relevantes associados ao controle metabólico (variável dependente). As variáveis independentes com um nível de significância de P < 0,1 na análise bivariada, foram incluídas no modelo. Resultados: foram avaliados 143 pacientes com DM2, idade de 59,3 ± 10,1 anos, duração conhecida do DM 7,5 ± 6,3 anos, índice de massa corporal (IMC) de 29,7 ± 5,2 kg/m².Destes, 94 pacientes (65,73%) apresentavam bom controle glicêmico. Os pacientes com mau controle glicêmico usavam mais anti-hiperglicemiantes orais como monoterapia (OR = 9,37; IC = 2,60-33,81; P=0,004) ou associados (OR = 31,08; IC = 7,42-130,15; P < 0,001). Da mesma maneira, não fizeram dieta em dias de festa (OR = 3,29; IC = 1,51-7,16; P = 0,012). A inclusão do conhecimento sobre diabetes não foi diferente entre os pacientes com bom ou mau controle glicêmico (OR = 1,08; IC = 0,97 - 1,21; P = 0,219). A análise multivariada demonstrou que a consulta com a enfermeira educadora (OR = 0,24; IC = 0,108-0,534; P = 0,003), com o endocrinologista (OR = 0,15 ; IC = 0,063-0,373; P = 0,001) e o uso de hipolipemiantes (OR = 0,10; IC = 0,016 - 0,72; P = 0,054) foram associados ao bom controle glicêmico, ajustados para a não realização de dieta em festas, uso de anti-hiperglicemiantes orais e conhecimento sobre diabetes. Conclusão: o controle metabólico em pacientes DM2 é influenciado pelas atividades de educação com enfermeira e endocrinologista. O tratamento do DM2 deve incluir atividades de educação de forma sistemática.

Curcumin-supplemented yoghurt improves physiological and biochemical markers of experimental diabetes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The influence of short-term diabetes mellitus and insulin therapy on alveolar bone loss in rats

Background: It is well known that the multiple direct and indirect consequences of hyperglycemia in diabetic individuals have been linked to a number of abnormal host effector mechanisms that could lead to an increased risk of developing periodontal disease.Objective: the aim of this study was to investigate the effect of short-term experimental diabetes and insulin therapy on the severity of alveolar bone loss in rats, and the effect of experimental periodontitis on glycemic control.Methods: Seventy-two male Wistar rats were divided into four groups: group I animals were submitted to dental ligature around lower right first molars (ligated); group II consisted of streptozotocin (STZ)-diabetic, ligated rats; group III represented STZ-diabetic, unligated rats; and group IV consisted of insulin-treated (6 U/day), STZ-diabetic, ligated rats. Blood glucose of all diabetic rats was monitored at regular intervals. Standardized digital radiographs were taken after killing at 7, 15 and 30 days to measure the amount of bone loss about the mesial root surface of the first molar tooth in each rat.Results: No significant (p < 0.05) changes in plasma glucose levels of insulin-treated diabetic rats were found among the different examinations after the beginning of insulin therapy. Rats from group II showed significantly greater increases in mean plasma glucose levels at 15 and 30 days after ligature placement compared with rats from group III (p < 0.05). Furthermore, in spite of the significant alveolar bone loss progression that was observed in groups I, II and IV (p < 0.00001; two-way ANOVA), no significant differences among these groups regarding the severity of bone loss (p = 0.77) and no significant interaction between treatment group and time (p = 0.81) were found.Conclusions: Within the limits of this study, it can be suggested that the severity of periodontal disease was not affected by short-term diabetes, and that experimental periodontitis increased blood glucose levels in uncontrolled diabetic rats.

Ultrastructural and proliferative features of the ventral lobe of the prostate in non-obese diabetic mice (NOD) following androgen and estrogen replacement associated to insulin therapy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Icodextrin reduces insulin resistance in non-diabetic patients undergoing automated peritoneal dialysis: results of a randomized controlled trial (STARCH)

Insulin resistance is a common risk factor in chronic kidney disease patients contributing to the high cardiovascular burden, even in the absence of diabetes. Glucose-based peritoneal dialysis (PD) solutions are thought to intensify insulin resistance due to the continuous glucose absorption from the peritoneal cavity. The aim of our study was to analyse the effect of the substitution of glucose for icodextrin on insulin resistance in non-diabetic PD patients in a multicentric randomized clinical trial. This was a multicenter, open-label study with balanced randomization (1:1) and two parallel-groups. Inclusion criteria were non-diabetic adult patients on automated peritoneal dialysis (APD) for at least 3 months on therapy prior to randomization. Patients assigned to the intervention group were treated with 2L of icodextrin 7.5%, and the control group with glucose 2.5% during the long dwell and, at night in the cycler, with a prescription of standard glucose-based PD solution only in both groups. The primary end-point was the change in insulin resistance measured by homeostatic model assessment (HOMA) index at 90 days. Sixty patients were included in the intervention (n = 33) or the control (n = 27) groups. There was no difference between groups at baseline. After adjustment for pre-intervention HOMA index levels, the group treated with icodextrin had the lower post-intervention levels at 90 days in both intention to treat [1.49 (95% CI: 1.23-1.74) versus 1.89 (95% CI: 1.62-2.17)], (F = 4.643, P = 0.03, partial η(2) = 0.078); and the treated analysis [1.47 (95% CI: 1.01-1.84) versus 2.18 (95% CI: 1.81-2.55)], (F = 7.488, P = 0.01, partial η(2) = 0.195). The substitution of glucose for icodextrin for the long dwell improved insulin resistance measured by HOMA index in non-diabetic APD patients.

Incretin receptors in non-neoplastic and neoplastic thyroid C cells in rodents and humans: relevance for incretin-based diabetes therapy

While incretins are of great interest for the therapy of diabetes 2, the focus has recently been brought to the thyroid, since rodents treated with glucagon-like peptide-1 (GLP-1) analogs were found to occasionally develop medullary thyroid carcinomas. Incretin receptors for GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) were therefore measured in various rodent and human thyroid conditions. In vitro GLP-1 and GIP receptor autoradiography were performed in normal thyroids, C-cell hyperplasia and medullary thyroid carcinomas in rodents. Receptor incidence and density were assessed and compared with the receptor expression in human thyroids, medullary thyroid carcinomas, and TT cells. GLP-1 receptors are expressed in C cells of normal rat and mice thyroids. Their density is markedly increased in rat C-cell hyperplasia and medullary thyroid carcinomas, where their incidence amounts to 100%. GIP receptors are neither detected in normal rodent thyroids nor in C-cell hyperplasia, but are present in all rat medullary thyroid carcinomas. No GLP-1 or GIP receptors are detected in normal human thyroids. Whereas only 27% of all human medullary thyroid carcinomas express GLP-1 receptors, up to 89% express GIP receptors in a high density. TT cells lack GLP-1 receptors but express GIP receptors. GLP-1 receptors are frequently expressed in non-neoplastic and neoplastic C cells in rodents while they are rarely detected in human C-cell neoplasia, suggesting species differences. Conversely, GIP receptors appear to be massively overexpressed in neoplastic C cells in both species. The presence of incretin receptors in thyroid C cell lesions suggests that this organ should be monitored before and during incretin-based therapy of diabetes.

Retinol-binding protein 4 is associated with components of the metabolic syndrome, but not with insulin resistance, in men with type 2 diabetes or coronary artery disease

AIMS/HYPOTHESIS: Retinol-binding protein 4 (RBP4) has recently been reported to be associated with insulin resistance and the metabolic syndrome. This study tested the hypothesis that RBP4 is a marker of insulin resistance and the metabolic syndrome in patients with type 2 diabetes or coronary artery disease (CAD) or in non-diabetic control subjects without CAD. METHODS: Serum RBP4 was measured in 365 men (126 with type 2 diabetes, 143 with CAD and 96 control subjects) and correlated with the homeostasis model assessment of insulin resistance index (HOMA-IR), components of the metabolic syndrome and lipoprotein metabolism. RBP4 was detected by ELISA and validated by quantitative Western blotting. RESULTS: RBP4 concentrations detected by ELISA were shown to be strongly associated with the results gained in quantitative Western blots. There were no associations of RBP4 with HOMA-IR or HbA(1c) in any of the groups studied. In patients with type 2 diabetes there were significant positive correlations of RBP4 with total cholesterol, LDL-cholesterol, VLDL-cholesterol, plasma triacylglycerol and hepatic lipase activity. In patients with CAD, there were significant associations of RBP4 with VLDL-cholesterol, plasma triacylglycerol and hepatic lipase activity, while non-diabetic control subjects without CAD showed positive correlations of RBP4 with VLDL-cholesterol and plasma triacylglycerol. CONCLUSIONS/INTERPRETATION: RBP4 does not seem to be a valuable marker for identification of the metabolic syndrome or insulin resistance in male patients with type 2 diabetes or CAD. Independent associations of RBP4 with pro-atherogenic lipoproteins and enzymes of lipoprotein metabolism indicate a possible role of RBP4 in lipid metabolism.

Age-dependent differences in demographics, risk factors, co-morbidity, etiology, management, and clinical outcome of acute ischemic stroke

BACKGROUND : Comparisons between younger and older stroke patients including comorbidities are limited. METHODS : Prospective data of consecutive patients with first ever acute ischemic stroke were compared between younger ( 45 years). RESULTS : Among 1004 patients, 137 (14 %) were diabetes (1 % versus 15 %; p < 0.0001), hypercholesterolemia (26 % versus 56 %; p < 0.0001), hypertension (19 % versus 65 %; p < 0.0001), coronary heart disease (14 % versus 40 %; p < 0.0001), and a lower mean Charlson co-morbidity index (CCI), (0.18 versus 0.84; p < 0.0001). Tobacco use was more prevalent in the young (39 % versus 26 %; P < 0.0001). Large artery disease (2 % versus 21 %; p < 0.0001), small artery disease (3 % versus 12 %; p = 0.0019) and atrial fibrillation (1 % versus 17 %; p = 0.001) were less common in young patients, while other etiologies (31 % versus 9 %; p < 0.0001), patent foramen ovale or atrial septal defect (44 % versus 26 %; p < 0.0001), and cervical artery dissection (26 % versus 7 %; p < 0.0001) were more frequent. A favorable outcome (mRS 0 or 1) was more common (57.4 % versus 46.9 %; p = 0.023), and mortality (5.1 % versus 12 %; p = 0.009) was lower in the young. After regression analysis, there was no independent association between age and outcome (p = 0.206) or mortality (p = 0.073). Baseline NIHSS score (p < 0.0001), diabetes (p = 0.041), and CCI (p = 0.002) independently predicted an unfavorable outcome. CONCLUSIONS : Younger patients were more likely to be female, had different risk factors and etiologies and fewer co-morbidities. There was no independent association between age and clinical outcome or mortality.

Metabolic inflexibility and insulin resistance in obese adolescents with non-alcoholic fatty liver disease.

BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is a comorbidity of childhood obesity. OBJECTIVE We examined whole-body substrate metabolism and metabolic characteristics in obese adolescents with vs. without NAFLD. SUBJECTS Twelve obese (BMI ≥ 95th percentile) adolescents with and without NAFLD [intrahepatic triglyceride (IHTG) ≥5.0% vs. <5.0%] were pair-matched for race, gender, age and % body fat. METHODS Insulin sensitivity (IS) was assessed by a 3-h hyperinsulinemic-euglycemic clamp and whole-body substrate oxidation by indirect calorimetry during fasting and insulin-stimulated conditions. RESULTS Adolescents with NAFLD had increased (p < 0.05) abdominal fat, lipids, and liver enzymes compared with those without NAFLD. Fasting glucose concentration was not different between groups, but fasting insulin concentration was higher (p < 0.05) in the NAFLD group compared with those without. Fasting hepatic glucose production and hepatic IS did not differ (p > 0.1) between groups. Adolescents with NAFLD had higher (p < 0.05) fasting glucose oxidation and a tendency for lower fat oxidation. Adolescents with NAFLD had lower (p < 0.05) insulin-stimulated glucose disposal and lower peripheral IS compared with those without NAFLD. Although respiratory quotient (RQ) increased significantly from fasting to insulin-stimulated conditions in both groups (main effect, p < 0.001), the increase in RQ was lower in adolescents with NAFLD vs. those without (interaction, p = 0.037). CONCLUSION NAFLD in obese adolescents is associated with adverse cardiometabolic profile, peripheral insulin resistance and metabolic inflexibility.

Understanding the roles of Non-homologous end joining and p53 after DNA damage

The inability to maintain genomic stability and control proliferation are hallmarks of many cancers, which become exacerbated in the presence of unrepaired DNA damage. Such genotoxic stresses trigger the p53 tumor suppressor network to activate transient cell cycle arrest allowing for DNA repair; if the damage is excessive or irreparable, apoptosis or cellular senescence is triggered. One of the major DNA repair pathway that mends DNA double strand breaks is non-homologous end joining (NHEJ). Abrogating the NHEJ pathway leads to an accumulation of DNA damage in the lymphoid system that triggers p53-mediated apoptosis; complete deletion of p53 in this system leads to aggressive lymphomagenesis. Therefore, to study the effect of p53-dependent cell cycle arrest, we utilized a hypomorphic, separation-of-function mutant, p53p/p, which completely abrogates apoptosis yet retains partial cell cycle arrest ability. We crossed DNA ligase IV deficiency, a downstream ligase crucial in mending breaks during NHEJ, into the p53p/p background (Lig4-/-p53p/p). The accumulation of DNA damage activated the p53/p21 axis to trigger cellular senescence in developing lymphoid cells, which absolutely suppressed tumorigenesis. Interestingly, these mice progressively succumb to severe diabetes. Mechanistic analysis revealed that spontaneous DNA damage accumulated in the pancreatic b-cells, a unique subset of endocrine cells solely responsible for insulin production to regulate glucose homeostasis. The genesis of adult b-cells predominantly occurs through self-replication, therefore modulating cellular proliferation is an essential component for renewal. The progressive accumulation of DNA damage, caused by Lig4-/-, activated p53/p21-dependent cellular senescence in mutant pancreatic b-cells that lead to islet involution. Insulin levels subsequently decreased, deregulating glucose homeostasis driving overt diabetes. Our Lig4-/-p53p/p model aptly depicts the dichotomous role of cellular senescence—in the lymphoid system prevents tumorigenesis yet in the endocrine system leads to the decrease of insulin-producing cells causing diabetes. To further delineate the function of NHEJ in pancreatic b-cells, we analyzed mice deficient in another component of the NHEJ pathway, Ku70. Although most notable for its role in DNA damage recognition and repair within the NHEJ pathway, Ku70 has NHEJ-independent functions in telomere maintenance, apoptosis, and transcriptional regulation/repression. To our surprise, Ku70-/-p53p/p mutant mice displayed a stark increase in b-cell proliferation, resulting in islet expansion, heightened insulin levels and hypoglycemia. Augmented b-cell proliferation was accompanied with the stabilization of the canonical Wnt pathway, responsible for this phenotype. Interestingly, the progressive onset of cellular senescence prevented islet tumorigenesis. This study highlights Ku70 as an important modulator in not only maintaining genomic stability through NHEJ-dependent functions, but also reveals a novel NHEJ-independent function through regulation of pancreatic b-cell proliferation. Taken in aggregate, these studies underscore the importance for NHEJ to maintain genomic stability in b-cells as well as introduces a novel regulator for pancreatic b-cell proliferation.

Treating type 2 diabetes through insulin resistance

Type 2 diabetes is an insidious disorder, with micro and/or macrovascular and nervous damage occurring in many patients before diagnosis. This damage is caused by hyperglycaemia and the diverse effects of insulin resistance. Obesity, in particular central obesity, is a strong pre-disposing factor for type 2 diabetes. Skeletal muscle is the main site of insulin-stimulated glucose disposal and appears to be the first organ that becomes insulin resistant in the diabetic state, with later involvement of adipose tissue and the liver. This study has investigated the use of novel agents to ameliorate insulin-resistance in skeletal muscle as a means of identifying intervention sites against insulin resistance and of improving glucose uptake and metabolism by skeletal muscle. Glucose uptake was measured in vitro by cultured L6 myocytes and isolated muscles from normal and obese diabetic ob/ob mice, using either the tritiated non-metabolised glucose analogue 2-deoxy-D-glucose or by glucose disposal. Agents studied included lipoic acid, isoferulic acid, bradykinin, lipid mobilising factor (provisionally synonymous with Zinca2 glycoprotein) and the trace elements lithium, selenium and chromium. The putative role of TNFa in insulin resistance was also investigated. Lipoic acid improved insulin-stimulated glucose uptake in normal and insulin resistance murine muscles, as well as cultured myocytes. Isoferulic acid, bradykinin and LMF also produced a transient increase in glucose uptake in cultured myocytes. Physiological concentrations of TNFa were found to cause insulin resistance in cultured, but no in excised murine muscles. The effect of the M2 metabolite of the satiety-inducing agent sibutramine on lipolysis in excised murine and human adipocytes was also investigated. M2 increased lipolysis from normal lean and obese ob/ob mouse adipocytes. Arguably the most important observation was that M2 also increased the lipolytic rate in adipocytes from catecholamine resistant obese subjects. The studies reported in this thesis indicate that a diversity of agents can improve glucose uptake and ameliorate insulin resistance. It is likely that these agents are acting via different pathways. This thesis has also shown that M2 can induce lipolysis in both rodent and human adipocytes. M2 hence has potential to directly reduce adiposity, in addition to well documented effects via the central nervous system.

Effect of insulin resistance on monounsaturated fatty acid levels : a multi-cohort non-targeted metabolomics and mendelian randomization study

Insulin resistance (IR) and impaired insulin secretion contribute to type 2 diabetes and cardiovascular disease. Both are associated with changes in the circulating metabolome, but causal directions have been difficult to disentangle. We combined untargeted plasma metabolomics by liquid chromatography/mass spectrometry in three non-diabetic cohorts with Mendelian Randomization (MR) analysis to obtain new insights into early metabolic alterations in IR and impaired insulin secretion. In up to 910 elderly men we found associations of 52 metabolites with hyperinsulinemic-euglycemic clamp-measured IR and/or β-cell responsiveness (disposition index) during an oral glucose tolerance test. These implicated bile acid, glycerophospholipid and caffeine metabolism for IR and fatty acid biosynthesis for impaired insulin secretion. In MR analysis in two separate cohorts (n = 2,613) followed by replication in three independent studies profiled on different metabolomics platforms (n = 7,824 / 8,961 / 8,330), we discovered and replicated causal effects of IR on lower levels of palmitoleic acid and oleic acid. A trend for a causal effect of IR on higher levels of tyrosine reached significance only in meta-analysis. In one of the largest studies combining "gold standard" measures for insulin responsiveness with non-targeted metabolomics, we found distinct metabolic profiles related to IR or impaired insulin secretion. We speculate that the causal effects on monounsaturated fatty acid levels could explain parts of the raised cardiovascular disease risk in IR that is independent of diabetes development.

Anti-inflammatory effect of exercise training in subjects with type 2 diabetes and the metabolic syndrome is dependent on exercise modalities and independent of weight loss

We investigated the effect of different exercise modalities on high sensitivity-C reactive protein (hs-CRP) and other inflammatory markers in patients with type 2 diabetes and the metabolic syndrome. Eighty-two patients were randomized into 4 groups: sedentary control (A); receiving counseling to perform low-intensity physical activity (B); performing prescribed and supervised high-intensity aerobic (C) or aerobic + resistance (D) exercise (with the same caloric expenditure) for 12 months. Evaluation of leisure-time physical activity and assessment of physical fitness, cardiovascular risk factors and inflammatory biomarkers was performed at baseline and every 3 months. Volume of physical activity increased and HbA1c decreased in Groups B–D. VO2max, HOMA-IR index, HDL-cholesterol, waist circumference and albuminuria improved in Groups C and D, whereas strength and flexibility improved only in Group D. Levels of hs-CRP decreased in all three exercising groups, but the reduction was significant only in Groups C and D, and particularly in Group D. Changes in VO2max and the exercise modalities were strong predictors of hs-CRP reduction, independent of body weight. Leptin, resistin and interleukin-6 decreased, whereas adiponectin increased in Groups C and D. Interleukin-1β, tumor necrosis factor-α and interferon-γ decreased, whereas anti-inflammatory interleukin-4 and 10 increased only in Group D. In conclusion, physical exercise in type 2 diabetic patients with the metabolic syndrome is associated with a significant reduction of hs-CRP and other inflammatory and insulin resistance biomarkers, independent of weight loss. Long-term high-intensity (preferably mixed) training, in addition to daytime physical activity, is required to obtain a significant anti-inflammatory effect.

Ghrelin gene-related peptides : multifunctional endocrine/autocrine modulators in health and disease

Ghrelin is a multi-functional peptide hormone which affects various processes including growth hormone and insulin release, appetite regulation, gut motility, metabolism and cancer cell proliferation. Ghrelin is produced in the stomach and in other normal and pathological cell types. It may act as an endocrine or autocrine/paracrine factor. The ghrelin gene encodes a precursor protein, preproghrelin, from which ghrelin and other potentially active peptides are derived by alternative mRNA splicing and/or proteolytic processing. The metabolic role of the peptide obestatin, derived from the preproghrelin C-terminal region, is controversial. However, it has direct effects on cancer cell proliferation. The regulation of ghrelin expression and the mechanisms through which the peptide products arise are unclear. We have recently re-examined the organisation of the ghrelin gene and identified several novel exons and transcripts. One transcript, which lacks the ghrelin-coding region of preproghrelin, contains the coding sequence of obestatin. Furthermore, we have identified an overlapping gene on the antisense strand of ghrelin, GHRLOS, which generates transcripts that may function as non-coding regulatory RNAs or code for novel, short bioactive peptides. The identification of these novel ghrelin-gene related transcripts and peptides raises critical questions regarding their physiological function and their role in obesity, diabetes and cancer.

Molecular markers of obesity and diabetes

Recently it has been shown that the consumption of a diet high in saturated fat is associated with impaired insulin sensitivity and increased incidence of type 2 diabetes. In contrast, diets that are high in monounsaturated fatty acids (MUFAs) or polyunsaturated fatty acids (PUFAs), especially very long chain n-3 fatty acids (FAs), are protective against disease. However, the molecular mechanisms by which saturated FAs induce the insulin resistance and hyperglycaemia associated with metabolic syndrome and type 2 diabetes are not clearly defined. It is possible that saturated FAs may act through alternative mechanisms compared to MUFA and PUFA to regulate of hepatic gene expression and metabolism. It is proposed that, like MUFA and PUFA, saturated FAs regulate the transcription of target genes. To test this hypothesis, hepatic gene expression analysis was undertaken in a human hepatoma cell line, Huh-7, after exposure to the saturated FA, palmitate. These experiments showed that palmitate is an effective regulator of gene expression for a wide variety of genes. A total of 162 genes were differentially expressed in response to palmitate. These changes not only affected the expression of genes related to nutrient transport and metabolism, they also extend to other cellular functions including, cytoskeletal architecture, cell growth, protein synthesis and oxidative stress response. In addition, this thesis has shown that palmitate exposure altered the expression patterns of several genes that have previously been identified in the literature as markers of risk of disease development, including CVD, hypertension, obesity and type 2 diabetes. The altered gene expression patterns associated with an increased risk of disease include apolipoprotein-B100 (apo-B100), apo-CIII, plasminogen activator inhibitor 1, insulin-like growth factor-I and insulin-like growth factor binding protein 3. This thesis reports the first observation that palmitate directly signals in cultured human hepatocytes to regulate expression of genes involved in energy metabolism as well as other important genes. Prolonged exposure to long-chain saturated FAs reduces glucose phosphorylation and glycogen synthesis in the liver. Decreased glucose metabolism leads to elevated rates of lipolysis, resulting in increased release of free FAs. Free FAs have a negative effect on insulin action on the liver, which in turn results in increased gluconeogenesis and systemic dyslipidaemia. It has been postulated that disruption of glucose transport and insulin secretion by prolonged excessive FA availability might be a non-genetic factor that has contributed to the staggering rise in prevalence of type 2 diabetes. As glucokinase (GK) is a key regulatory enzyme of hepatic glucose metabolism, changes in its activity may alter flux through the glycolytic and de novo lipogenic pathways and result in hyperglycaemia and ultimately insulin resistance. This thesis investigated the effects of saturated FA on the promoter activity of the glycolytic enzyme, GK, and various transcription factors that may influence the regulation of GK gene expression. These experiments have shown that the saturated FA, palmitate, is capable of decreasing GK promoter activity. In addition, quantitative real-time PCR has shown that palmitate incubation may also regulate GK gene expression through a known FA sensitive transcription factor, sterol regulatory element binding protein-1c (SREBP-1c), which upregulates GK transcription. To parallel the investigations into the mechanisms of FA molecular signalling, further studies of the effect of FAs on metabolic pathway flux were performed. Although certain FAs reduce SREBP-1c transcription in vitro, it is unclear whether this will result in decreased GK activity in vivo where positive effectors of SREBP-1c such as insulin are also present. Under these conditions, it is uncertain if the inhibitory effects of FAs would be overcome by insulin. The effects of a combination of FAs, insulin and glucose on glucose phosphorylation and metabolism in cultured primary rat hepatocytes at concentrations that mimic those in the portal circulation after a meal was examined. It was found that total GK activity was unaffected by an increased concentration of insulin, but palmitate and eicosapentaenoic acid significantly lowered total GK activity in the presence of insulin. Despite the fact that total GK enzyme activity was reduced in response to FA incubation, GK enzyme translocation from the inactive, nuclear bound, to active, cytoplasmic state was unaffected. Interestingly, none of the FAs tested inhibited glucose phosphorylation or the rate of glycolysis when insulin is present. These results suggest that in the presence of insulin the levels of the active, unbound cytoplasmic GK are sufficient to buffer a slight decrease in GK enzyme activity and decreased promoter activity caused by FA exposure. Although a high fat diet has been associated with impaired hepatic glucose metabolism, there is no evidence from this thesis that FAs themselves directly modulate flux through the glycolytic pathway in isolated primary hepatocytes when insulin is also present. Therefore, although FA affected expression of a wide range of genes, including GK, this did not affect glycolytic flux in the presence of insulin. However, it may be possible that a saturated FA-induced decrease in GK enzyme activity when combined with the onset of insulin resistance may promote the dys-regulation of glucose homeostasis and the subsequent development of hyperglycaemia, metabolic syndrome and type 2 diabetes.