Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011860 (type 2 diabetes)
 57,723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The importance of type 2 diabetes is due to its high prevalence, the difficulties in achieving optimal glucose control (financial, time, quality of life) and the high frequency of chronic microvascular and macrovascular complications that add very significantly to the morbidity, mortality and overall cost of the disease. Numerous risk factors have been identified that predict the future onset of type 2 diabetes in individuals and an early stage of the disease (impaired glucose tolerance) can often be identified. Insulin resistance is central to the pathogenesis and is initially compensated by an increased insulin secretion. Over time, insulin secretion progressively fails and diabetes appears. Several approaches have been proposed for the prevention of diabetes. Lifestyle changes (nutritional therapy and physical activity) have been shown to reduce the frequency of diabetes in small studies and are being assessed in the NIH-funded Diabetes Prevention Trial. Metformin, which reduces insulin resistance and hyperinsulinaemia, is being assessed in this same trial. Acarbose, which has been shown to reduce post-prandial insulin secretion and improve insulin resistance, is being assessed in the STOP-NIDDM trial. The ACE inhibitor ramipril has been shown in the HOPE study to reduce the appearance of diabetes by one third when given to patients with vascular disorders and this class of agents has been shown to improve insulin resistance. Another very promising approach is the use of thiazolidinediones (rosiglitazone, pioglitazone) to improve the insulin resistance and possibly preserve the beta cells by reducing the need for increased insulin secretion. These lifestyle changes and medications have been shown to be safe in the treatment of type 2 diabetes. There is a high probability that one of these approaches will be effective in delaying or preventing type 2 diabetes, and prevention may become a clinical reality in the near future.
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PMID:Prevention of type 2 diabetes. 1196 30

Recent developments in our understanding of the pathophysiology of polycystic ovary syndrome led to the introduction of new therapeutic approaches. It is apparent that a significant proportion of women with polycystic ovary syndrome have insulin resistance and compensatory hyperinsulinemia. Growing evidence indicates that elevated serum insulin induces hyperandrogenism, which in turn leads to anovulation and infertility. Hyperinsulinemia also contributes to the increased risk for cardiovascular disorders and type 2 diabetes mellitus. These concepts provide rationale for therapies focused on treatments of insulin resistance. In particular, weight loss and exercise have been shown to increase insulin sensitivity and improve ovulatory function. Metformin, an insulin-sensitizing agent, is particularly effective in women with polycystic ovary syndrome who have significant insulin resistance. Metformin use leads to a decrease in serum insulin and androgen levels as well as an improvement in ovulatory function. Moreover, it appears to ameliorate cardiovascular risk factors. Other approaches to ovulation induction in women with polycystic ovary syndrome include traditional therapies using clomiphene citrate or gonadotropins. In clomiphene-resistant subjects, one can consider laparoscopic ovarian drilling and other forms of partial ovarian resection or destruction.
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PMID:Optimizing ovulation induction in women with polycystic ovary syndrome. 1203 79

Metformin is an effective hypoglycemic drug that lowers blood glucose concentrations by decreasing hepatic glucose production and increasing glucose disposal in skeletal muscle; however, the molecular site of metformin action is not well understood. AMP-activated protein kinase (AMPK) activity increases in response to depletion of cellular energy stores, and this enzyme has been implicated in the stimulation of glucose uptake into skeletal muscle and the inhibition of liver gluconeogenesis. We recently reported that AMPK is activated by metformin in cultured rat hepatocytes, mediating the inhibitory effects of the drug on hepatic glucose production. In the present study, we evaluated whether therapeutic doses of metformin increase AMPK activity in vivo in subjects with type 2 diabetes. Metformin treatment for 10 weeks significantly increased AMPK alpha2 activity in the skeletal muscle, and this was associated with increased phosphorylation of AMPK on Thr172 and decreased acetyl-CoA carboxylase-2 activity. The increase in AMPK alpha2 activity was likely due to a change in muscle energy status because ATP and phosphocreatine concentrations were lower after metformin treatment. Metformin-induced increases in AMPK activity were associated with higher rates of glucose disposal and muscle glycogen concentrations. These findings suggest that the metabolic effects of metformin in subjects with type 2 diabetes may be mediated by the activation of AMPK alpha2.
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PMID:Metformin increases AMP-activated protein kinase activity in skeletal muscle of subjects with type 2 diabetes. 1208 35

Metformin is an insulin-sensitizing agent with potent antihyperglycemic properties. Its efficacy in reducing hyperglycemia in type 2 diabetes mellitus is similar to that of sulfonylureas, thiazolidinediones, and insulin. Metformin-based combination therapy is often superior to therapy with a single hypoglycemic agent. The antihyperglycemic properties of metformin are mainly attributed to suppressed hepatic glucose production, especially hepatic gluconeogenesis, and increased peripheral tissue insulin sensitivity. Although the precise mechanism of hypoglycemic action of metformin remains unclear, it probably interrupts mitochondrial oxidative processes in the liver and corrects abnormalities of intracellular calcium metabolism in insulin-sensitive tissues (liver, skeletal muscle, and adipocytes) and cardiovascular tissue.
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PMID:Metformin: an update. 1209 66

Metformin, a biguanide, is widely used as an oral hypoglycemic agent for the treatment of type 2 diabetes mellitus. The purpose of the present study was to investigate the role of organic cation transporter 1 (Oct1) in the disposition of metformin. Transfection of rat Oct1 cDNA results in the time-dependent and saturable uptake of metformin by the Chinese hamster ovary cell line with K(m) and V(max) values of 377 microM and 1386 pmol/min/mg of protein, respectively. Buformin and phenformin, two other biguanides, were also transported by rOct1 with a higher affinity than metformin: their K(m) values were 49 and 16 microM, respectively. To investigate the role of Oct1 in the disposition of metformin, the tissue distribution of metformin was determined in Oct1 gene-knockout mice after i.v. administration. Distribution of metformin to the liver in Oct1(-/-) mice was more than 30 times lower than that in Oct1(+/+) mice, and can be accounted for by the extracellular space. Distribution to the small intestine was also decreased in Oct1(-/-) mice, whereas that to the kidney as well as the urinary excretion profile showed only minimal differences. In conclusion, the present findings suggest that Oct1 is responsible for the hepatic uptake as well as playing a role in the intestinal uptake of metformin, whereas the renal distribution and excretion are mainly governed by other transport mechanism(s).
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PMID:Involvement of organic cation transporter 1 in hepatic and intestinal distribution of metformin. 1213 Jul 9

Metformin, a drug widely used to treat type 2 diabetes, was recently shown to activate the AMP-activated protein kinase (AMPK) in intact cells and in vivo. In this study we addressed the mechanism for this effect. In intact cells, metformin stimulated phosphorylation of the key regulatory site (Thr-172) on the catalytic (alpha) subunit of AMPK. It did not affect phosphorylation of this site by either of two upstream kinases in cell-free assays, although we were able to detect an increase in upstream kinase activity in extracts of metformin-treated cells. Metformin has been reported to be an inhibitor of complex 1 of the respiratory chain, but we present evidence that activation of AMPK in two different cell types is not a consequence of depletion of cellular energy charge via this mechanism. Whereas we have not established the definitive mechanism by which metformin activates AMPK, our results show that the mechanism is different from that of the existing AMPK-activating agent, 5-aminoimidazole-4-carboxamide (AICA) riboside. Metformin therefore represents a useful new tool to study the consequences of AMPK activation in intact cells and in vivo. Our results also show that AMPK can be activated by mechanisms other than changes in the cellular AMP-to-ATP ratio.
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PMID:The antidiabetic drug metformin activates the AMP-activated protein kinase cascade via an adenine nucleotide-independent mechanism. 1214 53

Polycystic ovary syndrome (PCOS) is a common endocrine condition that affects women of reproductive age. Anovulation, menstrual irregularities, hirsutism, and infertility are common clinical presentations. Long-term health concerns such as type II diabetes mellitus and, possibly, cardiovascular disease, have been linked to PCOS. Metformin, an oral hypoglycemic agent, has been recently advocated as treatment for some women with PCOS due to the association of PCOS with hyperinsulinemia. Metformin is utilized as sole therapy for ovulation induction as well as in combination with traditional ovulation-induction therapies. This review identified 23 prospective studies addressing the effects of metformin on PCOS. Because of the heterogeneity of the published reports, only a qualitative assessment of the data was possible. Review of this literature confirms a beneficial role of metformin in reducing insulin resistance in some women with PCOS. Other favourable biochemical effects include reduced free testosterone levels and increased sex hormone-binding globulin (SHBG). Metformin may improve menstrual regularity, leading to spontaneous ovulation, and improve ovarian response to conventional ovulation-induction therapies. There is, however, little evidence supporting the use of metformin to facilitate weight reduction, or improve serum lipids or hirsutism. Further evaluation is required to define the long-term effectiveness of metformin, who will benefit from metformin treatment, and the optimal duration of metformin therapy.
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PMID:Metformin and polycystic ovary syndrome: a literature review. 1219 59

The recognition of insulin resistance as a principal factor in the pathogenesis of polycystic ovarian syndrome (PCOS) has led to the use of insulin-lowering agents, also called 'insulin-sensitizing drugs', for its treatment. The most extensively studied insulin-lowering agent in the treatment of PCOS is metformin: an oral antihyperglycaemic agent used initially in the treatment of type 2 diabetes mellitus. Metformin is effective in the treatment of PCOS-related anovulation and infertility. Moreover, preliminary evidence indicates that metformin may also be effective in decreasing the risk of early spontaneous miscarriage in women with PCOS. Metformin also appears to induce cardioprotective effects on serum lipids as well as plasminogen activator inhibitor (PAI)-1 and may decrease the risk of development of type 2 diabetes. The highly promising therapeutic profile of metformin is related to the role of this agent in controlling an important aetiologic factor in the pathogenesis of PCOS: hyperinsulinaemia.
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PMID:Should patients with polycystic ovarian syndrome be treated with metformin? 1220 7

Gestational diabetes (GD) develops because pregnancy increases requirements for insulin secretion while increasing insulin resistance. Women with GD often have impaired pancreatic beta-cell compensation for insulin resistance. The nature of GD is currently contentious, with debate about its existence, diagnosis and ramifications for both mother and offspring from pregnancy into later life. Also contentious are the outcomes of intervention with diet, insulin, glyburide (Glynase trade mark, Pharmacia Upjohn) and metformin (Glucophage trade mark, Bristol-Myers Squibb). There is consensus that women with unequivocal GD have a significant risk of adverse perinatal outcomes and increased risk of later type 2 diabetes mellitus. Foetuses from pregnancies with GD have a higher risk of macrosomia (associated with higher rate of birth injuries), asphyxia, and neonatal hypoglycaemia and hyperinsulinaemia. Uncontrolled GD predisposes foetuses to accelerated, excessive fat accumulation, insulin resistance, pancreatic exhaustion secondary to prenatal hyperglycaemia and possible higher risk of child and adult obesity and type 2 diabetes mellitus later in adult life. However, there is no consensus as to whether glucose intolerance of a severity below unequivocal GD is related to adverse maternal, fetal or perinatal outcomes, and whether this relationship is a continuous one. If dietary intervention is not sufficient in the treatment of GD, then, historically, insulin has been added. Recent studies suggest that glyburide may be efficaciously substituted for insulin. Preliminary studies suggest that metformin may have the unique potential to prevent the development of GD.
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PMID:The contentious nature of gestational diabetes: diet, insulin, glyburide and metformin. 1243 90

The etiology, natural history, and relationship of insulin resistance to type 2 diabetes mellitus and the effects of insulin-sensitizing agents are described. Insulin resistance results from a combination of genetic and environmental factors and contributes to type 2 diabetes mellitus, dyslipidemia, hypertension, central (abdominal) obesity, and cardiovascular disease. Insulin resistance does not necessarily progress to impaired glucose tolerance or diabetes because insulin secretion by normal pancreatic beta cells can increase to compensate for reduced physiological activity. Diabetes may develop in insulin-resistant persons with inherited secretory and glucose-sensing defects in beta cells. The pathogenesis of diabetes appears to involve a progressive decrease in beta-cell mass, potentially triggered by abnormalities in adipocytokine release from intraabdominal fat cells. Metformin and the thiazolidinediones are used to treat insulin resistance, but their actions differ. Metformin reduces free-fatty-acid efflux from fat cells, thereby suppressing hepatic glucose production, and indirectly improves peripheral insulin sensitivity and endothelial function. Thiazolidinediones improve peripheral insulin sensitivity by reducing circulating free fatty acids but also by suppressing adipocytokines, which increase insulin resistance. Thiazolidinediones also improve endothelial function and may prevent or delay the onset of diabetes. Insulin is intrinsically antiatherogenic but may mediate arterial inflammation in insulin-resistant patients. Unlike metformin, the thiazolidinediones suppress this inflammatory pathway and may indirectly help preserve beta-cell function. Insulin resistance, resulting from a combination of genetic and environmental factors, plays a central role in type 2 diabetes mellitus. Diabetes may develop in insulin-resistant persons with inherited secretory and glucose-sensing defects in beta cells. Metformin and thiazolidinediones are insulin-sensitizing agents with different mechanisms of action and effects in patients with type 2 diabetes mellitus.
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PMID:Insulin resistance, diabetes, and the adipocyte. 1248 80


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