Lifestyle modifications in conjunction with antidiabetes medications can produce near-normal blood glucose concentrations in patients with type 2 diabetes mellitus (T2DM). Because these patients have increased cardiovascular morbidity and mortality, treatment strategies should also address the cardiovascular aspects of the disease, including blood pressure, lipids, and body weight. Since the prevalence of these abnormalities is increasingly secondary to poor diet and sedentary lifestyles and because most patients with T2DM are overweight/obese, clinicians are encouraged to help patients reduce body weight while correcting hyperglycemia by selecting treatment options that improve both parameters. The glucose-lowering properties of insulin and sulfonylureas are well known but they are also associated with weight gain. Thiazolidinediones are associated with weight gain as well as edema. However, this weight gain may be more peripheral than central, which may mitigate the risks associated with increased body fat. Metformin, the consensus first-line drug for the treatment of patients with T2DM, is weight neutral. Newer antidiabetes agents include incretin-based medications, such as the glucagon-like peptide-1 receptor agonists, which tend to decrease weight, and the dipeptidyl peptidase-4 inhibitors, which are weight neutral. less...

AIMS/HYPOTHESIS: In rodent adipocytes, activated AMP-activated protein kinase reduces the lipolytic rate. As the hypoglycaemic drugs metformin and thiazolidinediones activate this enzyme in rodents, we tested the hypothesis that in addition to their known actions they could have an anti-lipolytic effect in human adipocytes. METHODS: Adipose tissue was obtained from individuals undergoing plastic surgery. Adipocytes were isolated and incubated with lipolytic agents (isoprenaline, atrial natriuretic peptide) and biguanides or thiazolidinediones. Lipolysis was quantified by the glycerol released in the medium. AMP-activated protein kinase activity and phosphorylation state were determined using standard procedures. RESULTS: In human adipocytes, isoprenaline and atrial natriuretic peptide stimulated the lipolytic rate three- to fourfold. Biguanides and thiazolidinediones activated AMP-activated protein kinase and inhibited lipolysis by 30-40%, at least in part by inhibiting hormone-sensitive lipase translocation to the lipid droplet. Inhibition of AMP-activated protein kinase by compound C precluded this inhibitory effect on lipolysis. Stimulation of lipolysis also induced an activation of AMP-activated protein kinase concomitant with a drop in ATP concentration. CONCLUSIONS/INTERPRETATION: We show for the first time in human adipocytes that biguanides and thiazolidinediones activate AMP-activated protein kinase, thus counteracting lipolysis induced by lipolytic agents. In addition, beta-agonist- or ANP-stimulated lipolysis increases AMP-activated protein kinase activity. This is because of an increase in the AMP/ATP ratio, linked to activation of some of the released fatty acids into acyl-CoA. AMP-activated protein kinase activation could represent a physiological means of avoiding a deleterious drain of energy during lipolysis but could be used to restrain pharmacological release of fatty acids. less...

Various pharmacological approaches can be used to improve glucose homeostasis. These pharmacological treatments may be used individually for certain types of patients, or may be combined to provide a more ideal glycaemic control. Metformin is widely used in pediatric patients and is considered to be the most effective oral agent. Addition of metformin to insulin in pediatric patients with type 1 diabetes mellitus improves metabolic control. Metformin acts by promoting glucose utilization and reducing hepatic glucose production. In many patients with type 2 diabetes, hyperglycemia can be reduced with appropriate changes in diet and exercise, however, some patients with type 2 diabetes and insulin resistance syndromes need pharmacological therapy to improve their metabolic control The first oral agent used should be metformin. More severe pancreatic beta-cell dysfunction in the group of children requires insulin therapy. Some forms of monogenic diabetes can be successfully managed by sulphonylurea agents. less...

BACKGROUND: We used a mathematical model to estimate the contribution of urinary glucose excretion (UGE) to reported changes in body weight (BW) following oral antihyperglycemic agent (AHA) therapy. This modeling approach was used to gain novel insight into the mechanisms by which oral AHA affects BW. METHODS: Twenty-four hour glucose profiles were used to predict UGE before and after treatment with oral AHA. Modelpredicted changes in BW due to reduced UGE were compared with reported changes in BW to quantify non-UGEdependent effects (fluid retention, food intake, and energy expenditure). RESULTS: In type 2 diabetes patients [hemoglobin A1c (HbA1c) >7.3%], the energy lost to UGE is predicted to decrease an average of 100 kcal/day for each 1% decrease in HbA1c. This effect, alone, is predicted to increase BW 1.4 kg after 6 months. Differences from this value reported for changes in BW with oral AHA therapy (+1.4 kg for pioglitazone and rosiglitazone; -0.4 kg for glyburide; -0.9 kg for sitagliptin and vildagliptin; -2.3 kg for metformin) are therefore predicted to be due to additional, non-UGE-dependent mechanisms. CONCLUSIONS: Weight gain following thiazolidinedione therapy is predicted to result from both reduced UGE and non-UGE-dependent mechanisms. Reduced UGE alone is predicted to account for most of the weight gain reported following sulfonylurea therapy. Weight loss observed in response to metformin and weight maintenance observed in response to dipeptidyl peptidase-4 inhibitors may result from an increase in satiety, energy expenditure, or both. less...

BACKGROUND: Thiazolidinediones represent a novel class of drugs that exert pleiotropic effects at various levels and lower blood glucose through reduction of insulin resistance in patients with type 2 diabetes mellitus. MAIN PURPOSE: The nephro- and neuroprotective effects of rosiglitazone vs. glimepiride were evaluated in normoalbuminuric patients with type 2 diabetes mellitus. The relevance of several biomarkers in the diagnosis of incipient diabetic nephropathy and cerebral microangiopathy was also assessed. METHODS: A total of 34 normoalbuminuric patients with type 2 diabetes mellitus were enrolled in a 1-year open-label randomized controlled trial. Group A comprised 17 patients (7 men, 10 women, mean age 63 +/- 8.07 years) treated with rosiglitazone plus metformin; Group B comprised 17 patients (7 men, 10 women, mean age 63.2 +/- 7.19 years) treated with glimepiride plus metformin. All patients were assessed at initiation, at 6 months and by the end of the study concerning serum and urinary beta2-microglobulin, urinary a1-microglobulin, serum cystatin C, serum creatinine, glomerular filtration rate, C-reactive protein, fibrinogen, glycated hemoglobin, cholesterol, triglycerides, hemoglobin, and the urinary albumin/creatinine ratio (UACR). Cerebral hemodynamic parameters were also measured: pulsatility index and resistance index in the internal carotid artery and middle cerebral artery, and intima-media thickness in the common carotid artery. RESULTS: At 1 year there were differences between groups A and B regarding serum cystatin C (P < 0.04), urinary beta2-microglobulin (P < 0.004), urinary a1-microglobulin (P < 0.0001), C-reactive protein (P < 0.0001), fibrinogen (P < 0.0001), serum creatinine (P < 0.0024), glomerular filtration rate (P < 0.0010), UACR (P < 0.0001), and the cerebral hemodynamic indices. The increase in a1- and beta2-microglobulin preceded the occurrence of microalbuminuria. UACR correlated with urinary a1- microglobulin (r = 0.4854), urinary beta2-microglobulin (r = 0.4867), and serum cystatin C (r = 0.3702). The cerebrovascular parameters improved in group A vs. group B and correlated with urinary beta2- and a1-microglobulin, C-reactive protein, fibrinogen, glomerular filtration rate, and duration of diabetes. CONCLUSION: Rosiglitazone demonstrated its nephro- and neuroprotective effects in normoalbuminuric patients with type 2 diabetes mellitus by the end of the follow-up period and these effects were beyond glycemic control. Urinary beta2- and a1-microglobulin are significant biomarkers for incipient diabetic nephropathy and diabetic cerebral microangiopathy. These biomarkers showed that proximal tubule dysfunction may develop before the stage of microalbuminuria. less...

PURPOSE: To determine whether combination of sulfonylureas and metformin increases the risk of death from any cause in patients with type 2 diabetes. METHODS: A nested case-control study was conducted within a population-based cohort from the UK General Practice Research Database (GPRD). The cohort included patients over the age of 40 who were prescribed a first oral hypoglycaemic agent between 1 January 1988 and 30 June 2008. Cases included all patients who deceased during follow-up. Up to 10 controls were matched to each case on year of birth, date of cohort entry (+/-1 year) and duration of follow-up. Conditional logistic regression was used to estimate rate ratios (RRs) of death from any cause associated with the use of combination of sulfonylureas and metformin, relative to sulfonylurea monotherapy. RESULTS: The cohort comprised 84 231 users of oral hypoglycaemic agents, of whom 14 996 died from any cause during a mean of 4.3 years of follow-up (mortality rate 4.1 per 100 per year). Patients currently exposed to a combination of sulfonylureas and metformin were at a decreased risk of death from any cause compared to patients exposed to sulfonylurea monotherapy (adjusted RR: 0.77, 95%CI: 0.70, 0.85). Similar results were obtained for patients currently exposed to metformin monotherapy (adjusted RR: 0.70, 95%CI: 0.64, 0.75) when compared to sulfonylurea monotherapy. Patients had to be exposed to the combination therapy for at least 4 months prior to index date to experience a lower risk of mortality compared to sulfonylurea monotherapy. CONCLUSIONS: The combination of sulfonylureas and metformin does not increase the risk of death. In contrast, it may moderately reduce this risk compared to sulfonylurea monotherapy. Copyright (c) 2010 John Wiley & Sons, Ltd. less...

To investigate the effects of metformin on angiogenesis, on inflammatory cell accumulation and on production of endogenous cytokines in sponge implant in mice. Polyester-polyurethane sponges were implanted in Swiss mice and metformin (40 or 400mg/kg/day) was given orally for six days. The implants collected at day 7 postimplantation were processed for the assessment of hemoglobin (Hb), myeloperoxidase (MPO), N-acetylglucosaminidase (NAG) e collagen used as indexes for angiogenesis, neutrophil and macrophage accumulation and extracellular matrix deposition, respectively. Relevant inflammatory, angiogenic and fibrogenic cytokines were also determined. Metformin treatment attenuated the main components of the fibrovascular tissue, wet weight, vascularization (Hb content), macrophage recruitment (NAG activity), collagen deposition and the levels of transforming growth factor (TGF-beta1) intraimplant. A regulatory function of metformin on multiple parameters of main components of inflammatory angiogenesis has been revealed giving insight into the potential therapeutic underlying the actions of metformin. less...

Renal elimination of a number of cationic compounds is thought to be mediated by the organic cation transporter 2 (OCT2, SLC22A2), a drug uptake transporter expressed at the basolateral domain of renal tubular cells. Recently, the key efflux transporter for the secretion organic cations was identified as an electroneutral H(+)/organic cation exchanger termed the multidrug and toxin extrusion (MATE)-type transporter 1 (MATE1, SLC47A1). The key goals of this study were to assess the interplay between the renal cationic transporters OCT2 and MATE1 and the functional assessment of genetic variation in human MATE1. First the ability of various agents to interact with OCT2 or MATE1 mediated transport was determined using a recombinant vaccinia expression system. We were able to identify several drugs in clinical use with divergent inhibitory capacity for these transporters. Subsequently, we further assessed the effect of those compounds on the cellular accumulation of shared substrates using OCT2 and MATE1 double transfected cells. Consistent with data obtained using single transporter transfected cells, compounds that exhibited preferential inhibition of MATE1 such as rapamycin and mitoxantrone induced significant cellular accumulation of cationic substrates. We next assessed the functional relevance of MATE1 genetic polymorphisms. Significant loss of transport activity for metformin and TEA was noted for two non-synonymous SNPs c.404T>C (p.159T>M) and c.1012G>A (p.338V>A). The c.404T>C was only seen in Asian subjects with an allele frequency of 1%, the c.1012G>A SNP was much more common, especially among those of African descent. In conclusion, we show that coordinate function of MATE1 with OCT2 likely contributes to the vectorial renal elimination of organic cationic drugs and that altered activity of MATE1, whether by drugs or polymorphisms, should be considered as an important determinant of renal cationic drug elimination. Key words: Organic Cation Transporter, drug-drug interactions, polymorphisms, Drug Transport less...

AIMS/HYPOTHESIS: As adding metformin to insulin therapy has been advocated in type 1 diabetes, we conducted a systematic review of published clinical trials and clinical trial databases to assess the effects on HbA(1c), weight, insulin-dose requirement and adverse effects. METHODS: We constructed evidence tables and fitted a fixed-effects model (inverse variance method) in order to assess heterogeneity between studies and give a crude measure of each overall treatment effect. RESULTS: Of 197 studies identified, nine involved randomisation with informed consent of patients with type 1 diabetes to metformin (vs placebo or comparator) in either a parallel or crossover design for at least 1 week. We noted marked heterogeneity in study design, drug dose, age of participants and length of follow-up. Metformin was associated with reductions in: (1) insulin-dose requirement (5.7-10.1 U/day in six of seven studies); (2) HbA(1c) (0.6-0.9% in four of seven studies); (3) weight (1.7-6.0 kg in three of six studies); and (4) total cholesterol (0.3-0.41 mmol/l in three of seven studies). Metformin was well tolerated, albeit with a trend towards increased hypoglycaemia. Formal estimates of combined effects from the five trials which reported appropriate data indicated a significant reduction in insulin dose (6.6 U/day, p < 0.001) but no significant reduction in HbA(1c) (absolute reduction 0.11%, p = 0.42). No reported trials included cardiovascular outcomes. CONCLUSIONS/INTERPRETATION: Metformin reduces insulin-dose requirement in type 1 diabetes but it is unclear whether this is sustained beyond 1 year and whether there are benefits for cardiovascular and other key clinical outcomes. less...

OBJECTIVES: The primary objective of our study was to estimate the frequency of undiagnosed Vitamin B12 deficiency amongst subjects with type 2 diabetes who were not taking Metformin for at least the past 5 years. The secondary objective was to ascertain if Vitamin B12 deficiency amongst the type 2 diabetes subjects was due to nutritional deficiency or malabsorption. METHODS: Vitamin B12 levels were measured in 44 subjects with diabetes (40-70 years). 21/44 (48%) had low vitamin B12 levels (<200 microgram/dL). 10/21 subjects agreed to enter an intervention phase comprising oral mecobalamin 1500 microgram/day for 3 months. Those subjects who failed to normalize Vitamin B12 levels after oral supplementation alone would be presumed to have Vitamin B12 deficiency due to malabsorption. RESULTS: Almost one-half of type 2 diabetes subjects not taking Metformin had biochemically proven vitamin B12 deficiency. 10/10 subjects had normalized their Vitamin B12 levels after 3 months of oral supplementation. CONCLUSION: We conclude that Vitamin B12 deficiency is common amongst type 2 diabetes subjects and is nutritional in nature. In addition to intensive glycemic control, Vitamin B12 supplementation should also be considered for treatment of diabetic neuropathy. In almost 50% of low vitamin B12 subjects the deficiency was correctable with oral supplementation alone. This indeed is an important finding, as taking oral Vitamin B12 supplementation is easy, convenient and readily accepted by patients. This is a novel finding and stresses the need for aggressive and early diagnosis and treatment to avoid complications of Vitamin B12 deficiency. less...