Effect of metformin and rosiglitazone combination therapy in patients with type 2 diabetes mellitus: a randomized controlled trial

Redefining the role of thiazolidinediones in the management of type 2 diabetes

There is a need to evaluate oral glucose-lowering agents not only for their value in achieving glycemic control but also for their impact on cardiac risk factor modification. This article reviews the evidence base for the two thiazolinediones currently available, pioglitazone and rosiglitazone. These drugs exert their effects through actions affecting metabolic control, lipid profiles, and the vascular wall. They have been shown to be as efficacious in establishing glycemic control, in both monotherapy and combination therapy regimens, as more traditional oral agents, and may be able to sustain that control in the long term. Both thiazolidinediones have demonstrated favorable effects on markers of cardiovascular disease. Evidence from the large PROactive outcomes study suggests that pioglitazone may exert protective effects in patients with type 2 diabetes and macrovascular disease. Thiazolidinediones are generally well tolerated but they can cause weight gain, induce fluid retention, and may contribute to bone loss in postmenopausal women. The place of thiazolidinediones in the management of type 2 diabetes is well established. The potential for additional benefits in reducing macrovascular risk encourages further long-term study of these agents.

Thiazolidinedione use is associated with better survival in hemodialysis patients with non-insulin dependent diabetes

Cardiovascular mortality is especially high among dialysis patients with diabetes, as is morbidity due to protein energy wasting. Given that both of these factors may be decreased by thiazolidinedione treatment, we studied the effect of thiazolidinedione use on survival among chronic dialysis patients in a national cohort of 5290 incident dialysis patients with diabetes. Thiazolidinedione use was assessed according to prescription data, and the analyses were stratified based on insulin use due to observed interaction. In the primary analysis, thiazolidinedione treatment was associated with significantly lower all-cause mortality among insulin-free but not insulin-requiring subjects, with adjusted hazards ratios of 0.53 (0.31-0.89) and 0.82 (0.46-1.47) respectively. Sensitivity analyses found the findings to be robust with respect to confounding by indication, severity of the diabetes, potential reverse causality, and time varying exposure patterns. The mechanism of this decline in all-cause mortality will need to be examined after these studies are confirmed.

Thiazolidinediones: effects on the development and progression of type 2 diabetes and associated vascular complications

In addition to reducing hyperglycaemia, the metabolic actions of TZDs (pioglitazone and rosiglitazone) in theory might improve the prognosis of patients with type 2 diabetes. However, it appears from recent data that pioglitazone and rosiglitazone have different cardiovascular risk profiles. The scope of this paper is to examine the benefits and risks of pioglitazone and rosiglitazone. Three large clinical studies (DREAM, and ADOPT with rosiglitazone; PROactive with pioglitazone) have recently been reported. A lower annual rate of decline of ss-cell function observed with rosiglitazone in the ADOPT study, compared with metformin and glyburide (glibenclamide), along with a reduced progression to insulin use seen with pioglitazone in the PROactive study, provides evidence that TZDs are effective in treating progressive hyperglycaemia. In PROactive, although the primary endpoint was not met, pioglitazone was associated with a reduction in a secondary composite endpoint of clinical cardiovascular events in high-risk patients with existing macrovascular disease who were already receiving other glycaemic and cardiovascular medications. Further evidence supporting an anti-atherogenic effect of pioglitazone was gained from the PERISCOPE study of carotid intima-media thickness. Recent controversy concerning a possible increased risk of myocardial infarction associated with rosiglitazone has fuelled uncertainty about the risk-benefit profile of this agent. In 2008, an update of an American Diabetes Association-European Association for the Study of Diabetes consensus statement on initiation and adjustment of therapy in patients with type 2 diabetes advised clinicians against using rosiglitazone. Skeletal fractures have recently emerged as a side effect of both TZDs. Available data suggest that cardiovascular benefits observed with pioglitazone might not be a class effect of TZDs.

Oral combination therapy: repaglinide plus metformin for treatment of type 2 diabetes

Type 2 diabetes is characterized by decreases in insulin secretion and insulin sensitivity. Several classes of oral antidiabetic medications are currently approved for the treatment of type 2 diabetes. A stepwise treatment approach from monotherapy to combination therapy is traditionally used; however, the frequency of treatment failure with monotherapy has resulted in a move towards earlier treatment with combination therapies that target the two principal defects in glycaemic control. One such combination regimen is repaglinide (a prandial glucose regulator that increases insulin release) plus metformin (an insulin sensitizer that inhibits hepatic glucose output, increases peripheral glucose uptake and utilization and minimizes weight gain). Findings from several clinical trials have shown that combination therapy with repaglinide plus metformin is well tolerated and results in greater reductions of haemoglobin A(1c) and fasting plasma glucose values compared with either monotherapy. Repaglinide may also provide a more suitable alternative to combination therapy with sulphonylureas and metformin because of its reduced propensity for hypoglycaemia. The combination regimen of repaglinide plus metformin should therefore be considered as a valuable option in the management of patients with type 2 diabetes when monotherapy is no longer adequate.

Cardiovascular outcomes in trials of oral diabetes medications: a systematic review

BACKGROUND

A wide variety of oral diabetes medications are currently available for the treatment of type 2 diabetes mellitus, but it is unclear how these agents compare with respect to long-term cardiovascular risk. Our objective was to systematically examine the peer-reviewed literature on the cardiovascular risk associated with oral agents (second-generation sulfonylureas, biguanides, thiazolidinediones, and meglitinides) for treating adults with type 2 diabetes.

METHODS

We searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials, from inception through January 19, 2006. Forty publications of controlled trials that reported information on cardiovascular events (primarily myocardial infarction and stroke) met our inclusion criteria. Using standardized protocols, 2 reviewers serially abstracted data from each article. Trials were first described qualitatively. For comparisons with 4 or more independent trials, results were pooled quantitatively using the Mantel-Haenszel method. Results are presented as odds ratios (ORs) and corresponding 95% confidence intervals (CIs).

RESULTS

Treatment with metformin hydrochloride was associated with a decreased risk of cardiovascular mortality (pooled OR, 0.74; 95% CI, 0.62-0.89) compared with any other oral diabetes agent or placebo; the results for cardiovascular morbidity and all-cause mortality were similar but not statistically significant. No other significant associations of oral diabetes agents with fatal or nonfatal cardiovascular disease or all-cause mortality were observed. When compared with any other agent or placebo, rosiglitazone was the only diabetes agent associated with an increased risk of cardiovascular morbidity or mortality, but this result was not statistically significant (OR, 1.68; 95% CI, 0.92-3.06).

CONCLUSIONS

Meta-analysis suggested that, compared with other oral diabetes agents and placebo, metformin was moderately protective and rosiglitazone possibly harmful, but lack of power prohibited firmer conclusions. Larger, long-term studies taken to hard end points and better reporting of cardiovascular events in short-term studies will be required to draw firm conclusions about major clinical benefits and risks related to oral diabetes agents.

Targeting the pathophysiology of type 2 diabetes: rationale for combination therapy with pioglitazone and exenatide

OBJECTIVE

The objectives of this article are to review the pathophysiology of type 2 diabetes mellitus (T2DM), present the rationale for a pathophysiologically based treatment approach for patients with T2DM and discuss the role of the therapeutic combination of pioglitazone and exenatide in the management of T2DM.

METHODS

References were identified from searches of the PubMed database that were conducted in May 2007, October 2007 and March 2008 and updates to product labeling that occurred between May 2007 and December 2007. Information was selected for inclusion on the basis of its relevance to the pathophysiology of T2DM or the clinical use of thiazolidinediones or exenatide. Discussion of other anti-diabetic treatment strategies is not included.

RESULTS

T2DM results from a combination of insulin resistance and beta-cell dysfunction. The combination of a thiazolidinedione and an incretin mimetic offers a combination of characteristics (e.g., glycemic control, reduced insulin resistance, decreased weight, potential cardiovascular benefits, beta-cell preservation) that addresses many of the pathophysiologic underpinnings of T2DM. A recent small placebo-controlled study assessed the effects of exenatide used with a thiazolidinedione (TZD; pioglitazone or rosiglitazone) with or without metformin. Exenatide demonstrated a greater incidence of glycosylated hemoglobin (HbA(1c)) < 7%; greater reductions in fasting blood glucose, postprandial plasma glucose and body weight; and improved beta-cell function versus the TZD/placebo group. However, exenatide was associated with a high dropout rate, and the 16-week duration of treatment in this study precluded evaluation of the long-term effects of the exenatide/pioglitazone combination. Furthermore, exenatide/pioglitazone has not been compared with any other anti-diabetic combination in a head-to-head clinical study.

CONCLUSIONS

Dual effects on insulin sensitivity (TZD) and insulin secretion (exenatide) make the TZD/exenatide combination a rational treatment option for patients who do not attain glycemic control with a single agent. Studies undertaken to evaluate the effects on cardiovascular outcomes and the potential for prevention of T2DM with impaired glucose tolerance may reveal additional advantages of this combination approach.

Addition of Thiazolidinedione or Exenatide to Oral Agents in Type 2 Diabetes: A Meta-Analysis

Background:

The introduction of several new therapeutic agents for the treatment of type 2 diabetes mellitus has led to significant challenges for providers in deciding which agent to select during the disease course.

Objective:

To provide a relative comparison of the efficacy and safety of adding thiazolidinediones (TZDs) or exenatide to oral agents for the management of type 2 diabetes mellitus by performing meta-analyses of relevant published studies.

Methods:

We systematically searched PubMed, MEDLINE, CINHAL, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, EMBASE (inception to March 2008 for all databases), and abstracts presented at the 2006 and 2007 American Diabetes Association conferences to identify all relevant publications. Studies were included in the analysis if they (1) were published in English, (2) were prospective, randomized, and controlled with placebo or comparator, (3) were at least 24 weeks' duration, (4) included nonpregnant adults with type 2 diabetes, (5) were full-text, peer-reviewed articles examining the efficacy of either TZDs (rosiglitazone or pioglitazone) or exenatide in combination with other oral drugs, and (6) included hemoglobin A1C (AIC) outcomes in a manner that allowed data analysis. We evaluated mean change in A1C levels, proportion of subjects reaching A1C goals of less than 7%, mean change in fasting plasma glucose (FPG) and body weight, and the occurrence of nonsevere hypoglycemia and gastrointestinal adverse events.

Results:

A total of 5212 TZD and 3562 exenatide publications were identified. After critical evaluation, 22 publications met all of the inclusion criteria for the meta-analysis. A1C was reduced from baseline for TZDs (weighted mean difference –0.80%; 95% CI –1.10 to –0.50) and exenaiide (weighted mean difference –0.60%; 95% CI –1.04 to –0.16), Compared with controls, TZD- and exenatide-based therapies had odds ratios greater than 1 for reaching A1C targets of less than 7% (TZD OR 2.27; 95% CI 1.22 to 4.24 and exenatide OR 2.90; 95% CI 1.28 to 6.55). FPG concentrations were reduced significantly from baseline in the TZD-based regimens (weighted mean difference –29.58 mg/dL; 95% CI –39.27 to –19.89), but did not achieve significance in the exenatide trials (weighted mean difference –8.77 mg/dL; 95% CI –28.85 to 11.31). Body weight was reduced with exenatide (weighted mean difference –2.74 kg; 95% CI –4.85 to –0.64) and increased in subgroup analyses for TZDs (weighted mean difference 2.19 kg; 95% CI 1.24 to 3.14). There was no significant association between TZD or exenatide therapy and the risk of nonsevere hypoglycemia. The odds ratios for nausea, vomiting, and diarrhea with exenatide relative to controls were 9.02 (95% CI 3.66 to 22.23), 4.56 (95% CI 3.13 to 6.65), and 2.96 (95% CI 2.05 to 4.26), respectively.

Conclusions:

TZDs and exenatide have modest but beneficial effects on glycemic control and are relatively safe in regard to the adverse events studied. TZDs produce greater improvement in glycemic control, while exenatide Is associated with reduction in body weight.

A retrospective evaluation of congestive heart failure and myocardial ischemia events in 14,237 patients with type 2 diabetes mellitus enrolled in 42 short-term, double-blind, randomized clinical studies with rosiglitazone

PURPOSE

Retrospectively investigate potential associations between rosiglitazone and congestive heart failure (CHF) and, separately, events of myocardial ischemia.

METHODS

Data from 14 237 individuals in 42 short-term, double-blind, randomized studies of rosiglitazone versus placebo or active diabetes medications were analyzed across seven treatment comparisons using an exact logistic regression model, adjusted for number of major cardiovascular risk factors and duration of exposure.

RESULTS

CHF incidence ranged 0-1.27% (SAEs) and 0.12-2.42% (all AEs) with rosiglitazone versus 0.07-0.75% (SAEs) and 0.25-1.36% (all AEs) with control. Higher odds ratios (95%CI) were observed for CHF SAEs with sulfonylurea- and insulin-containing combinations: rosiglitazone monotherapy versus placebo, 0.25 (<0.01-4.75); rosiglitazone monotherapy versus sulfonylurea/metformin monotherapy, 0.23 (<0.01-2.14); sulfonylurea + rosiglitazone versus sulfonylurea monotherapy, 0.95 (0.01-75.20); metformin + rosiglitazone versus metformin monotherapy, 0.60 (0.00-8.28); metformin + rosiglitazone versus metformin + sulfonylurea, 1.04 (0.39-2.86); sulfonylurea + metformin + rosiglitazone versus sulfonylurea + metformin, 3.15 (0.35-150.52); insulin + rosiglitazone versus insulin monotherapy, 1.63 (0.52-6.01). Myocardial ischemia incidence ranged 0.75-1.40% (SAEs) and 1.49-2.77% (all AEs) with rosiglitazone versus 0.21-2.04% (SAEs) and 0.56-2.38% (all AEs) with control. Each comparison had an OR >1, with wide confidence intervals generally including unity. With data pooling, more events of myocardial ischemia were observed with rosiglitazone (2.00%) versus control (1.53%) (HR 1.30, 95%CI 1.004-1.69).

CONCLUSIONS

CHF incidence may be greater when rosiglitazone is combined with sulfonylureas or insulin. When data were pooled, more events of myocardial ischemia were observed with rosiglitazone versus control. Final results from RECORD will allow a more rigorous evaluation of the cardiovascular safety profile.

Exenatide once weekly versus twice daily for the treatment of type 2 diabetes: a randomised, open-label, non-inferiority study

BACKGROUND

Exenatide is an incretin mimetic that shares glucoregulatory properties with glucagon-like peptide 1 (GLP-1), and improves glycaemic control, with progressive bodyweight reductions, when administered twice a day in patients with type 2 diabetes. We compared the efficacy of a once-weekly formulation of exenatide to that of a twice daily dose.

METHODS

A 30-week, randomised, non-inferiority study compared a long-acting release formulation of exenatide 2 mg administered once weekly to 10 mug exenatide administered twice a day, in 295 patients with type 2 diabetes (haemoglobin A(1c) [HbA(1c)] 8.3% [SD 1.0], mean fasting plasma glucose 9 [SD 2] mmol/L, weight 102 [SD 20] kg, diabetes duration 6.7 [SD 5.0] years). The patients were naive to drug therapy, or on one or more oral antidiabetic agents. The primary endpoint was the change in HbA(1c) at 30 weeks. This study is registered with ClinicalTrials.gov, number NCT00308139.

FINDINGS

At 30 weeks, the patients given exenatide once a week had significantly greater changes in HbA(1c) than those given exenatide twice a day (-1.9 [SE 0.1%] vs -1.5 [0.1%], 95% CI -0.54% to -0.12%; p=0.0023). A significantly greater proportion of patients receiving treatment once a week versus twice a day achieved target HbA(1c) levels of 7.0% or less (77%vs 61% of evaluable patients, p=0.0039).

INTERPRETATION

Exenatide once weekly resulted in significantly greater improvements in glycaemic control than exenatide given twice a day, with no increased risk of hypoglycaemia and similar reductions in bodyweight.

Winners and losers at the rosiglitazone gamble A meta-analytical approach at the definition of the cardiovascular risk profile of rosiglitazone

The treatment with rosiglitazone could be associated with increased risk for myocardial infarction (MI). This meta-analysis is aimed at identifying moderators of the effect of rosiglitazone on the risk of MI and chronic heart failure (CHF) in type 2 diabetic patients. The risk ratio (RR) of MI and CHF was calculated for each trial as the ratio of incidence density in rosiglitazone and comparator groups. A total of 86 trials were included. After adjusting for trial duration, RR for MI showed a significant inverse correlation with mean baseline HbA1c, triglycerides, and LDL-cholesterol (r=-0.24, -0.45, and -0.33, respectively; all p<0.05). Conversely, rosiglitazone-associated risk of MI was increased in trials with higher mean BMI or greater proportion of insulin-treated patients (r=0.26 and 0.42, respectively; p<0.05). Lower triglyceride levels were also associated with a higher rosiglitazone-induced risk of CHF (r=-0.23, p<0.05). Treatment with rosiglitazone could have divergent effects on cardiovascular risk, depending on the characteristics of the patients. Benefits could outweigh harms in patients with poor glycemic control and worse lipid profile; conversely, the drug could increase the risk of MI in obese or insulin-treated patients.

Metformin therapy and clinical uses

Metformin is now established as a first-line antidiabetic therapy for the management of type 2 diabetes. Its early use in treatment algorithms is supported by lack of weight gain, low risk of hypoglycaemia and its mode of action to counter insulin resistance. The drug's anti-atherosclerotic and cardioprotective effects have recently been confirmed in prospective and retrospective studies, and appear to reflect a collection of glucose-independent effects on the vascular endothelium, suppressant effects on glycation, oxidative stress and formation of adhesion molecules, stimulation of fibrinolysis and favourable effects on the lipid profile. Although avoidance of troublesome gastrointestinal tolerability issues requires careful dose titration, the risk of serious adverse events is considered low provided that contra-indications (especially with respect to renal function) are observed. As many of its actions go beyond glucose lowering, emerging evidence indicates potential benefits in other insulin-resistant states and possibly tumour suppression.

Efficacy and safety of sitagliptin when added to ongoing metformin therapy in patients with type 2 diabetes

AIM

To assess the addition of sitagliptin to ongoing metformin therapy in patients with type 2 diabetes who were inadequately controlled [haemoglobin A(1c) (HbA(1c)) 7-11%] on metformin monotherapy.

METHODS

Patients (n = 273) on metformin (>/=1500 mg/day) were randomized to receive the addition of once-daily placebo, sitagliptin 100 mg or rosiglitazone 8 mg in a 1 : 1 : 1 ratio for 18 weeks. The efficacy analysis was based on the all-patients-treated population using an analysis of co-variance with change in HbA(1c) from baseline as the primary endpoint.

RESULTS

The mean baseline HbA(1c) was 7.7% for the entire cohort. After 18 weeks, both active add-on therapies led to greater improvements in HbA(1c) from baseline: -0.73% for sitagliptin (p < 0.001 vs. placebo) and -0.79% for rosiglitazone compared with -0.22% for placebo. No difference was observed between the sitagliptin and rosiglitazone treatments (0.06% [95% confidence interval (CI): -0.14 to 0.25]). The proportion of patients achieving an HbA(1c) < 7% was greater with sitagliptin (55%) and rosiglitazone (63%) compared with placebo (38%). Body weight increased from baseline with rosiglitazone (1.5 kg) compared with body weight reduction with sitagliptin (-0.4 kg) and placebo (-0.8 kg). The difference in body weight between the sitagliptin and rosiglitazone groups was 1.9 kg (95% CI: 1.3-2.5). In a prespecified analysis, the proportion of patients experiencing a greater than 3-kg increase in body weight was 21% in the rosiglitazone group compared with 2% in both the sitagliptin and placebo groups. Both active treatments were generally well tolerated, with no increased risk of hypoglycaemia or gastrointestinal adverse events compared with placebo.

CONCLUSIONS

In this 18-week study, the addition of sitagliptin was effective and well tolerated in patients with type 2 diabetes inadequately controlled with metformin monotherapy. Treatment with sitagliptin produced similar reductions in HbA(1c) compared with the addition of rosiglitazone.

Interaction of oral antidiabetic drugs with hepatic uptake transporters: focus on organic anion transporting polypeptides and organic cation transporter 1

OBJECTIVE

The uptake of drugs into hepatocytes is a key determinant for hepatic metabolism, intrahepatic action, their subsequent systemic plasma concentrations, and extrahepatic actions. In vitro and in vivo studies indicate that many drugs used for treatment of cardiovascular diseases (e.g., oral antidiabetic drugs, statins) are taken up into hepatocytes by distinct organic anion transporters (organic anion transporting polypeptides [OATPs]; gene symbol SLCO/SLC21) or organic cation transporters (OCTs; gene symbol SLC22). Because most patients with type 2 diabetes receive more than one drug and inhibition of drug transporters has been recognized as a new mechanism underlying drug-drug interactions, we tested the hypothesis of whether oral antidiabetic drugs can inhibit the transport mediated by hepatic uptake transporters.

RESEARCH DESIGN AND METHODS

Using stably transfected cell systems recombinantly expressing the uptake transporters OATP1B1, OATP1B3, OATP2B1, or OCT1, we analyzed whether the antidiabetic drugs repaglinide, rosiglitazone, or metformin influence the transport of substrates and drugs (for OATPs, sulfobromophthalein [BSP] and pravastatin; for OCT1, 1-methyl-4-phenylpyridinium [MPP(+)] and metformin).

RESULTS

Metformin did not inhibit the uptake of OATP and OCT1 substrates. However, OATP-mediated BSP and pravastatin uptake and OCT1-mediated MPP(+) and metformin uptake were significantly inhibited by repaglinide (half-maximal inhibitory concentration [IC(50)] 1.6-5.6 micromol/l) and rosiglitazone (IC(50) 5.2-30.4 micromol/l).

CONCLUSIONS

These in vitro results demonstrate that alterations of uptake transporter function by oral antidiabetic drugs have to be considered as potential mechanisms underlying drug-drug interactions.

Dissociation between the insulin-sensitizing effect of rosiglitazone and its effect on hepatic and intestinal lipoprotein production

CONTEXT

Despite its potent, well-documented insulin-sensitizing effects, rosiglitazone (RSG) does not effectively ameliorate the hypertriglyceridemia of insulin-resistant or diabetic individuals and has even been shown to slightly but significantly increase triglyceride-rich lipoproteins (TRL) in some studies. The mechanism of this effect is currently not known.

OBJECTIVE

We investigated the effect of RSG treatment on TRL metabolism.

DESIGN

This was a 12-wk, single-sequence, cross-over study of rosiglitazone vs. placebo for 6 wk.

PARTICIPANTS

Participants included 17 nondiabetic men with a broad range of insulin sensitivity.

INTERVENTION

INTERVENTION included rosiglitazone 8 mg/d vs. placebo for 6 wk.

MAIN OUTCOME MEASURE

TRL metabolism (concentration, production and catabolic rates) was assessed in a constant fed state with a 12-h primed constant infusion of [D3]l-leucine and multicompartmental modeling.

RESULTS

RSG treatment resulted in significant insulin sensitization with no change in body weight. Fasting plasma triglyceride (TG) concentration, however, was higher with RSG vs. placebo (P = 0.0006), as were fasting and fed TRL-TG, TRL-apoB-48, and TRL-apoB-100 (fed TRL-apoB-48: 0.93 +/- 0.08 vs. 0.76 +/- 0.07 mg/dl, P =0.017, and fed TRL-apoB-100: 15.57 +/- 0.90 vs. 13.71 +/- 1.27 mg/dl, P = 0.029). This small but significant increase in plasma TRL concentration was explained by a tendency for RSG to increase TRL production and reduce particle clearance, as indicated by the significantly increased production to clearance ratios for both apoB-48-containing (0.43 +/- 0.03 vs. 0.34 +/- 0.03, P = 0.048) and apoB-100-containing (7.0 +/- 0.4 vs. 6.2 +/- 0.6, P = 0.029) TRL.

CONCLUSION

These data indicate dissociation between the insulin-sensitizing effects of RSG and absence of anticipated reductions in production rates of apoB-100- and apoB-48-containing-TRL particles, which may explain the absence of TG lowering seen in humans treated with this agent.

Impact of therapeutic advances on hypoglycaemia in type 2 diabetes

Patients with type 2 diabetes experience hypoglycaemia less frequently than those with type 1 diabetes. Some protection against hypoglycaemia is afforded by the relatively intact glucose counter-regulatory pathways that characterize the pathophysiology of early type 2 diabetes. To some extent, this protection explains why hypoglycaemic episodes in intensively treated individuals with type 2 diabetes, when they occur, are rarely severe. As diabetes progresses and therapy intensifies to achieve recommended glycaemic goals, hypoglycaemia frequency and severity increase. Thus, when it comes to instituting intensive therapy, fear of hypoglycaemia may contribute to health-care providers' 'clinical inertia'. Because maintaining glycaemic control is so important to both public and individual health, many new therapies and technologies have been developed. This manuscript reviews and considers whether these advancements in therapy make glycaemic goals easier to achieve by minimizing hypoglycaemia. Putting the hypoglycaemia experienced by type 2 diabetes patients into appropriate clinical perspective, the impact of recent progress made in pharmacotherapy, drug delivery systems, and BG monitoring on hypoglycaemia incidence is largely positive. The extent to which this progress can effect improvement over traditional therapies will, however, depend upon patient (and provider) education, motivation and behaviour change.

Effects of rosiglitazone on body fat distribution and insulin sensitivity in Korean type 2 diabetes mellitus patients

The objective of the study was to investigate the effects of rosiglitazone (RSG), a thiazolidinedione derivative, on body fat distribution and insulin sensitivity in Korean subjects with type 2 diabetes mellitus. This study was a phase IV, multicenter, single-blind, positive-controlled parallel group study. Eighty-nine patients with type 2 diabetes mellitus, aged 30 to 75 years, were enrolled in this study. Their fasting plasma glucose levels ranged from 126 to 270 mg/dL, and subjects had hemoglobin A1c levels of greater than 7.0%. We compared the effect of the treatment with glibenclamide plus RSG 4 mg/d (increased to 8 mg/d after 6 months) with glibenclamide plus placebo on body fat distributions, which were determined by computed tomography scanning and glycemic and insulinemic responses to oral glucose load. During the 12-month treatment period, the difference between the changes in the ratio of the intraabdominal adipose tissue (IAAT) to abdominal subcutaneous adipose tissue areas (SAT) between treatment groups was significant (from 1.13 +/- 0.53 to 1.00 +/- 0.40 in the RSG group and from 0.92 +/- 0.54 to 0.96 +/- 0.62 in the placebo group, P = .0351). The glycemic responses to oral glucose load (area under the curve, millimoles per liter per hour) were improved in the RSG group with 12 months of treatment (from 4.88 +/- 1.10 to 4.38 +/- 1.35 in 1 hour and from 13.78 +/- 2.83 to 12.16 +/- 2.52 in 2 hours), and the difference between the changes of the glycemic response showed statistical significance between groups (RSG group vs placebo group: -0.53 +/- 1.42 vs 0.38 +/- 1.31, difference in 1 hour; -0.76 +/- 2.98 vs 1.43 +/- 2.58, difference in 2 hours). However, there was no difference between insulin responses from baseline to follow-up and no differences in the change in insulin response between groups. In Korean subjects with type 2 diabetes mellitus, 12 months of treatment with RSG may increase SAT, but may have a neutral effect on IAAT, resulting in a decrease in the IAAT:SAT ratio. The RSG treatment improved the glucose control in type 2 diabetes mellitus. However, it is important to determine whether the glucose-lowering effect of RSG occurs mainly through direct enhancement of insulin sensitivity.

Effect of pioglitazone on heart function and N-terminal pro-brain natriuretic peptide levels of patients with type 2 diabetes

We assessed the effect of the addition of pioglitazone on metabolic control and heart function of patients with type 2 diabetes already receiving sulfonylurea plus metformin. Forty-four patients were given 30 mg of pioglitazone for 3 months. Physical examination, laboratory tests including N-terminal pro-brain natriuretic peptide (NT-proBNP), and echocardiography, were performed at baseline and at study completion. Target HbA(1c) levels were achieved by 44.2% of the patients. Pioglitazone ameliorated lipid profile and lowered liver enzymes and C-reactive protein. Significant increases in NT-proBNP by 39% (P < 0.005) were noticed, but echocardiographic parameters were not altered, even in high-risk subgroups (patients older than 60 years, with diabetes for more than 10 years, with hypertension, with elevated baseline NT-proBNP levels, with left ventricular hypertrophy). In patients with a greater than 60% increase in NT-proBNP levels, a significant increase in left ventricular ejection fraction (P < 0.05) and in fractional shortening (P < 0.05) was found. None of the patients developed edema or signs or symptoms of heart failure. Triple oral combination antidiabetic treatment is an effective therapeutic strategy and weight gain does not abrogate its beneficial actions. Pioglitazone does not affect heart function and even though it increases NT-proBNP, this appears to represent a reaction to volume overload.

Update on diabetes diagnosis and management

BACKGROUND

The American Diabetes Association has established recommendations for the testing of undiagnosed people. Once diagnosed, those with diabetes must strive to maintain a level of glucose control that results in a metabolism that approaches that of people without diabetes. The dentist also can provide risk-reduction strategies for people prone to develop diabetes, and refer patients with signs and symptoms suggestive of diabetes to physicians.

METHODS

The authors describe criteria for establishing a diagnosis of diabetes and for identifying people at high risk of developing the disease. A combination of approaches in the medical management of type 1 and type 2 diabetes mellitus is presented, along with target outcomes.

RESULTS

Patients with diabetes maintain a glycosylated hemoglobin value of no higher than 7 percent. New therapeutic research includes early clinical trials of islet cell transplantation and therapeutic cloning from human stem cells, which may provide an alternate source of insulin-producing islet cells and, thus, may offer a potential cure for diabetes.

CONCLUSIONS

Rigorous metabolic control of diabetes can be achieved through a combination of therapeutic modalities and the establishment and maintenance of target outcomes. The dentist can implement preventive strategies and refer patients with signs and symptoms suggestive of diabetes to physicians.

CLINICAL IMPLICATIONS

The dentist and physician must work together as a team to achieve rigorous metabolic control of diabetes in their patients.

Peroxisome proliferator-activated receptor-gamma agonists and diabetes: current evidence and future perspectives

Since their initial availability in 1997, the thiazolidinediones (TZDs) have become one of the most commonly prescribed classes of medications for type 2 diabetes. In addition to glucose control, the TZDs have a number of pleiotropic effects on myriad traditional and non-traditional risk factors for diabetes. TZDs may benefit cardiovascular parameters, such as lipids, blood pressure, inflammatory biomarkers, endothelial function and fibrinolytic state. In this review, we summarise the experimental, preclinical and clinical data regarding the effects of the TZDs in conditions for which they are indicated and discuss their potential in the treatment of other conditions.

The importance of beta-cell management in type 2 diabetes

Despite intervention with effective oral glucose-lowering agents, most patients with type 2 diabetes will experience a gradual loss of glycaemic control. Irrespective of underlying levels of insulin resistance, the progressive failure and loss of beta-cells are ultimately responsible for the onset of frank type 2 diabetes. The mechanisms responsible for loss of beta-cell function are likely to be multifactorial, but may involve toxicity because of elevated glucose and/or lipid levels, increased secretory demand because of insulin resistance, amyloid deposition and altered levels of cytokines. Preservation of beta-cell function is now gaining recognition as a critical target in the management of type 2 diabetes. For patients with frank type 2 diabetes, preservation of beta-cell function has the potential to reduce or stabilise the progression of type 2 diabetes and to decrease the need for additional oral glucose-lowering agents and/or insulin therapy. There is a growing body of animal/preclinical evidence for improved and preserved beta-cell function with current glucose-lowering agents, such as the thiazolidinediones, metformin and the glucagon-like peptide-1 analogue, exenatide. Clinical studies incorporating indirect measures of beta-cell function also support a protective effect with some agents. A number of novel therapies that are currently under investigation may also offer beta-cell structural and functional protection, including dipeptidyl peptidase IV inhibitors and cannabinoid receptor type 1 blockers. Emerging evidence from interventional trials suggests that both intensive lifestyle changes and pharmacotherapy can delay or possibly prevent the onset of type 2 diabetes in high-risk individuals. For patients newly diagnosed with type 2 diabetes, early and aggressive intervention strategies that combine maximal glucose-lowering efficacy alongside potential beta-cell preserving properties may provide an opportunity to delay or prevent progression of the disease.

Peroxisome proliferator-activated receptors and the metabolic syndrome

The prevalence of the metabolic syndrome is rapidly increasing. This syndrome is characterized by metabolic disturbances, such as abnormal lipid and carbohydrate metabolism and a low-grade inflammatory state. PPARs play an important role in these metabolic processes, which makes them effective targets for treatment and prevention of the metabolic syndrome. Synthetic PPAR agonists, such as fibrates and thiazolidinediones are already used to treat hyperlipidemia and diabetes mellitus, respectively. Besides synthetic ligands, dietary fatty acids and fatty acid derivatives can also bind to an activate PPARs. As demonstrated with ligand-binding assays, PPARs have a clear preference of binding polyunsaturated fatty acids. Monounsaturated fatty acids are also very effective in binding PPARs, whereas saturated fatty acids are poor PPAR binders. However, ligand binding does not necessarily mean transcriptional activation. Therefore, it is important to investigate transactivation properties of dietary fatty acids as PPAR agonists and their role in metabolic reactions. Furthermore, human intervention studies comparing the effects of natural versus synthetic ligands side-by-side may reveal specific fatty acids that exert beneficial PPAR-mediated metabolic effects. The ability of PPARs to sense fatty acids and to mediate lipid metabolism, glucose metabolism and the inflammatory state makes them excellent targets for dietary modulation in order to prevent and treat the metabolic syndrome and associated diseases. This review discusses the role and function of PPARs and their ligands in light of the metabolic syndrome.

Insulin signaling and glucose transport in insulin resistant human skeletal muscle

Insulin increases glucose uptake and metabolism in skeletal muscle by signal transduction via protein phosphorylation cascades. Insulin action on signal transduction is impaired in skeletal muscle from Type 2 diabetic subjects, underscoring the contribution of molecular defects to the insulin resistant phenotype. This review summarizes recent work to identify downstream intermediates in the insulin signaling pathways governing glucose homeostasis, in an attempt to characterize the molecular mechanism accounting for skeletal muscle insulin resistance in Type 2 diabetes. Furthermore, the effects of pharmaceutical treatment of Type 2 diabetic patients on insulin signaling and glucose uptake are discussed. The identification and characterization of pathways governing insulin action on glucose metabolism will facilitate the development of strategies to improve insulin sensitivity in an effort to prevent and treat Type 2 diabetes mellitus.

Metabolic syndrome and type 2 diabetes: can we stop the weight gain with diabetes?

Many patients with type 2 diabetes also have the metabolic syndrome with its cardinal features of central adiposity, insulin resistance, dyslipidemia, and hypertension. Although there is strong evidence for the importance of tight glycemic control in minimizing the microvascular complications of diabetes, many of the current therapies used for optimizing glycemic control also cause weight gain. With this treatment-induced weight gain, there is a risk of worsening the patient's insulin resistance. Physicians need to be aware of this vicious cycle in their overweight type 2 diabetic patients. This article reviews the strategies currently available to achieve glycemic control while at the same time minimizing weight gain and the associated complications.

Potential role of oral DPP-4 inhibitors in the ADA/EASD consensus statement algorithm for achieving and maintaining tight glycaemic control in type 2 diabetes: recommendations for oral antidiabetic agents

A recently published American Diabetes Association/European Association for the Study of Diabetes consensus statement on the management of hyperglycaemia in type 2 diabetes emphasises the achievement and maintenance of normal glycaemic control and the rapid addition of medications and transition to new regimens when glycaemic goals are not achieved or sustained. An algorithm for the use of available interventions is supplied to help practitioners avoid prolonged periods of inadequate glycaemic control. Recommendations include rapid transition to combination treatment with oral agents and with insulin plus oral agents. The currently available oral agents are reviewed here with respect to the consensus statement recommendations, and the characteristics of the new class of oral dipeptidyl peptidase-4 inhibitors are summarised. These agents offer clinically meaningful reductions in HbA1c without significant risk of hypoglycaemia and without causing weight gain; they also offer the theoretical potential of improving or maintaining beta-cell function and thus, favourably affecting the progressive loss of function that is characteristic of type 2 diabetes. Potential uses of these agents in the context of the consensus statement recommendations are considered.

Management of antiretroviral treatment-related complications

Antiretroviral therapy for HIV restores immune function, controls viral replication, decreases opportunistic infections, and extends lifespan to near-normal for infected individuals. However, successful HIV therapy has been accompanied by the emergence of treatment-related complications, with an impact not yet fully understood. This article reviews six common complications of antiretroviral therapy, including hyperlactatemia/lactic acidosis, hypersensitivity reactions, abnormal glucose metabolism, dyslipidemia, body composition changes, and cardiovascular disease. A comprehensive approach to management of antiretroviral-related complications includes awareness of (1) risk factors for adverse reactions, (2) clinical syndromes suggestive of an evolving complication, and (3) evidence-based monitoring and treatment strategies. Fluency in options for preventing and managing complications can provide maximal opportunity to balance treatment effects with quality of life.

Rosiglitazone for type 2 diabetes mellitus

BACKGROUND

Diabetes has long been recognised as a strong, independent risk factor for cardiovascular disease, a problem which accounts for approximately 70% of all mortality in people with diabetes. Prospective studies show that compared to their non-diabetic counterparts, the relative risk of cardiovascular mortality for men with diabetes is two to three and for women with diabetes is three to four. The two biggest trials in type 2 diabetes, the United Kingdom Prospective Diabetes Study (UKPDS) and the University Group Diabetes Program (UGDP) study did not reveal a reduction of cardiovascular endpoints through improved metabolic control. Theoretical benefits of the peroxisome proliferator activated receptor gamma (PPAR-gamma) activator rosiglitazone on endothelial function and cardiovascular risk factors might result in fewer macrovascular disease events in people with type 2 diabetes mellitus.

OBJECTIVES

To assess the effects of rosiglitazone in the treatment of type 2 diabetes.

SEARCH STRATEGY

Studies were obtained from computerised searches of MEDLINE, EMBASE and The Cochrane Library.

SELECTION CRITERIA

Studies were included if they were randomised controlled trials in adult people with type 2 diabetes mellitus and had a trial duration of at least 24 weeks.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Pooling of studies by means of fixed-effects meta-analysis could be performed for adverse events only.

MAIN RESULTS

Eighteen trials which randomised 3888 people to rosiglitazone treatment were identified. Longest duration of therapy was four years with a median of 26 weeks. Published studies of at least 24 weeks rosiglitazone treatment in people with type 2 diabetes mellitus did not provide evidence that patient-oriented outcomes like mortality, morbidity, adverse effects, costs and health-related quality of life are positively influenced by this compound. Metabolic control measured by glycosylated haemoglobin A1c (HbA1c) as a surrogate endpoint did not demonstrate clinically relevant differences to other oral antidiabetic drugs. Occurrence of oedema was significantly raised (OR 2.27, 95% confidence interval (CI) 1.83 to 2.81). The single large RCT (ADOPT - A Diabetes Outcomes Progression Trial) indicated increased cardiovascular risk. New data on raised fracture rates in women reveal extensive action of rosiglitazone in various body tissues.

AUTHORS' CONCLUSIONS

New studies should focus on patient-oriented outcomes to clarify the benefit-risk ratio of rosiglitazone therapy. Safety data and adverse events of all investigations (published and unpublished) should be made available to the public.

Metformin/rosiglitazone combination pill (Avandamet) for the treatment of patients with Type 2 diabetes

More than 150 million people worldwide have diabetes, the prevalence of which is increasing so rapidly that the number of adults with diabetes in the world will rise to 300 million by the year 2025. In the US, approximately 21 million people have diabetes and in some areas of the country, the prevalence is as high as 50%. The pathophysiologic hallmarks consist of insulin resistance and progressive pancreatic beta-cell dysfunction. An increased metabolic demand for insulin due to increased insulin resistance usually precedes the development of hyperglycemia. At early stages, pancreatic beta cells compensate for insulin resistance by hypersecretion of insulin. However, the period of beta-cell compensation is followed by beta-cell failure, in which the pancreas fails to secrete sufficient insulin and diabetes ensues. Biguanides and thiazolidinediones (TZDs) are two unique classes of oral antidiabetic agents that are the most commonly used medications to improve insulin sensitivity. They have no direct effect on beta-cell function, although some indirect mechanisms of actions may help to preserve beta-cell function or slow beta-cell apoptosis. Their glucose-lowering effect results from improving insulin sensitivity in a complementary fashion: metformin reduces hepatic glucose production and TZDs increase skeletal muscle glucose use. The combination of metformin and rosiglitazone in a single pill (Avandamet), was approved by the FDA in October 2002 for the treatment of diabetes. As insulin resistance is a pathophysiologic cornerstone of diabetes and cardiovascular disease, the use of Avandamet represents an optimal approach to the treatment of diabetes. This manuscript reviews the pharmacology, safety and benefits of the combination pill Avandamet.

Antidiabetic medications in overweight/obese patients with type 2 diabetes: drawbacks of current drugs and potential advantages of incretin-based treatment on body weight

The vast majority of patients with type 2 diabetes are overweight or obese. Lifestyle intervention to lose weight is recommended in most diabetic patients to improve glycaemic control and reduce associated risk factors for microvascular and macrovascular complications. Even modest weight loss can significantly improve glucose homeostasis and lessen cardiometabolic risk factors, although achieving this level of weight reduction remains difficult for many patients. Complicating the matter, many agents used to target hyperglycaemia are associated with weight gain, making management of overweight or obese patients with type 2 diabetes quite challenging. Incretin-based therapies with the new classes of glucagon-like peptide-1 mimetics (e.g. exenatide, liraglutide) and dipeptidyl peptidase 4 (DPP-4) inhibitors (e.g. sitagliptin, vildagliptin) may be of particular value in the treatment of overweight/obese type 2 diabetic patients because of their efficacy in improving glycaemic control and their favourable or neutral effects on body weight. In addition, DPP-4 inhibitors have a low risk for causing hypoglycaemia, undesirable gastrointestinal effects, or other prominent adverse effects that might limit their use. These classes of drugs hold promise for the treatment of type 2 diabetes, alone or in combination with other classes of antidiabetic agents.

Effect of rosiglitazone on the risk of myocardial infarction and death from cardiovascular causes

BACKGROUND

Rosiglitazone is widely used to treat patients with type 2 diabetes mellitus, but its effect on cardiovascular morbidity and mortality has not been determined.

METHODS

We conducted searches of the published literature, the Web site of the Food and Drug Administration, and a clinical-trials registry maintained by the drug manufacturer (GlaxoSmithKline). Criteria for inclusion in our meta-analysis included a study duration of more than 24 weeks, the use of a randomized control group not receiving rosiglitazone, and the availability of outcome data for myocardial infarction and death from cardiovascular causes. Of 116 potentially relevant studies, 42 trials met the inclusion criteria. We tabulated all occurrences of myocardial infarction and death from cardiovascular causes.

RESULTS

Data were combined by means of a fixed-effects model. In the 42 trials, the mean age of the subjects was approximately 56 years, and the mean baseline glycated hemoglobin level was approximately 8.2%. In the rosiglitazone group, as compared with the control group, the odds ratio for myocardial infarction was 1.43 (95% confidence interval [CI], 1.03 to 1.98; P=0.03), and the odds ratio for death from cardiovascular causes was 1.64 (95% CI, 0.98 to 2.74; P=0.06).

CONCLUSIONS

Rosiglitazone was associated with a significant increase in the risk of myocardial infarction and with an increase in the risk of death from cardiovascular causes that had borderline significance. Our study was limited by a lack of access to original source data, which would have enabled time-to-event analysis. Despite these limitations, patients and providers should consider the potential for serious adverse cardiovascular effects of treatment with rosiglitazone for type 2 diabetes.

A double-blind randomized study comparing the effects of continuing or not continuing rosiglitazone + metformin therapy when starting insulin therapy in people with Type 2 diabetes

AIMS

To compare the efficacy and safety of either continuing or discontinuing rosiglitazone + metformin fixed-dose combination when starting insulin therapy in people with Type 2 diabetes inadequately controlled on oral therapy.

METHODS

In this 24-week double-blind study, 324 individuals with Type 2 diabetes inadequately controlled on maximum dose rosiglitazone + metformin therapy were randomly assigned to twice-daily premix insulin therapy (target pre-breakfast and pre-evening meal glucose < or = 6.5 mmol/l) in addition to either rosiglitazone + metformin (8/2000 mg) or placebo.

RESULTS

Insulin dose at week 24 was significantly lower with rosiglitazone + metformin (33.5 +/- 1.5 U/day, mean +/- se) compared with placebo [59.0 +/- 3.0 U/day; model-adjusted difference -26.6 (95% CI -37.7, -15,5) U/day, P < 0.001]. Despite this, there was greater improvement in glycaemic control [HbA(1c) rosiglitazone + metformin vs. placebo 6.8 +/- 0.1 vs. 7.5 +/- 0.1%; difference -0.7 (-0.8, -0.5)%, P < 0.001] and more individuals achieved glycaemic targets (HbA(1c) < 7.0% 70 vs. 34%, P < 0.001). The proportion of individuals reporting at least one hypoglycaemic event during the last 12 weeks of treatment was similar in the two groups (rosiglitazone + metformin vs. placebo 25 vs. 27%). People receiving rosiglitazone + metformin in addition to insulin reported greater treatment satisfaction than those receiving insulin alone. Both treatment regimens were well tolerated but more participants had oedema [12 (7%) vs. 4 (3%)] and there was more weight gain [3.7 vs. 2.6 kg; difference 1.1 (0.2, 2.1) kg, P = 0.02] with rosiglitazone + metformin.

CONCLUSIONS

Addition of insulin to rosiglitazone + metformin enabled more people to reach glycaemic targets with less insulin, and was generally well tolerated.

Pharmacotherapy for the treatment of patients with type 2 diabetes mellitus: rationale and specific agents

Type 2 diabetes, the most common form of diabetes, is characterized by abnormalities in hepatic glucose production, insulin resistance, and a progressive decline in beta-cell function over time. To treat effectively the individual with type 2 diabetes, the provider must have a thorough understanding of the underlying pathophysiology to provide treatment that precisely addresses the metabolic abnormalities. Currently, the provider who cares for subjects with type 2 diabetes can choose an antidiabetic agent from no less than eight pharmacologic classes. These classes include agents that increase insulin secretion, improve insulin action, and delay absorption of carbohydrates. The newer treatments available, specifically incretin therapy, address a previously unmet need in diabetes by modulating glucose supply. The currently available agents can be combined and combination therapy markedly improves glycemic control. This allows the provider to design regimens to specifically address underlying abnormalities. A review of all currently available agents is provided.

Inclusion of biomarkers for detecting perturbations in the heart and lung and lipid/carbohydrate metabolism in National Toxicology Program studies

Environmental factors and exposures may contribute to many serious diseases afflicting humans. Biomarkers are useful to understand disease processes and identify early events leading to disease. The National Toxicology Program (NTP) convened a workshop in September 2006 to help identify biomarkers that could be used in toxicology studies with rodents to predict disease outcome and detect early events in disease processes. Expert scientists reviewed biomarkers for disease/injury related to the heart, lung, and/or changes in lipid/carbohydrate metabolism and made recommendations for those that could be incorporated into NTP studies on a routine or selective basis. Although numerous biomarkers were discussed, only a few were considered amenable for routine use. This article summarizes recommendations for the most promising biomarkers and presents the NTP perspective on those that will be included in the bioassay program on a routine or special study basis. Breakout group reports and additional information on the workshop, including participants, presentations, and background materials, are posted on the NTP Web site http://ntp.niehs.nih.gov/go/20940.

Comparison of extended-release metformin in combination with a sulfonylurea (glyburide) to sulfonylurea monotherapy in adult patients with type 2 diabetes: a multicenter, double-blind, randomized, controlled, phase III study

BACKGROUND

Metformin is widely used in the management of type 2 diabetes, either as monotherapy or in combination with other oral antihyperglycemic agents such as sulfonylureas and thiazolidinediones. Combination treatment with metformin and sulfonylurea in patients who failed monotherapy has been reported to be effective in maintaining glycemic control.

OBJECTIVE

The purpose for this study was to compare the efficacy and tolerability of extended-release metformin (MER) administered with a sulfonylurea (glyburide) to sulfonylurea monotherapy in patients with type 2 diabetes.

METHODS

This multicenter, double-blind, randomized, controlled study enrolled adult patients with type 2 diabetes who were either drug naive or previously treated with oral diabetic medications and who had not achieved glycemic control. Patients were stabilized on sulfonylurea (10 mg/d for 2 weeks, then 15 mg/d for 4 weeks) then randomly assigned at base line to receive MER (1500 mg QD, 1000 mg BID, or 2000 mg QD) plus sulfonylurea (MER+S) or sulfonylurea monotherapy for 24 weeks. Patients were evaluated every 1 to 2 weeks during sulfonylurea stabilization and initial metformin treatment, and then every 4 weeks until study end. The primary efficacy end point was glycemic control as determined by changes in glycosylated hemoglobin (HbA(1c)) from baseline to study end between those receiving combination MER+S treatment and those receiving sulfonylurea monotherapy. Adverse events (AEs) were recorded throughout the study by direct questioning, self-reporting by patients, and from the results of physical examinations and clinical laboratory tests.

RESULTS

A total of 741 patients were enrolled. Of these, 134 patients were stabilization failures, 607 patients were randomized, 575 patients received treatment and were included in the intent-to-treat population, and 417 patients completed the study per protocol. There were no significant differences between treatment groups for any demographic or baseline characteristics (all patients: mean [SD] age, 53.0 [10.6] years; male sex, 54.6% [314/575]; race, white, 58.8% [338/575], Hispanic, 28.5% [164/575]; mean [SD] weight, 97.0 [22.2] kg; obese [body mass index > or =30 kg/m(2)], 69.4% [399/575] ). There were significant decreases from baseline in mean fasting plasma glucose (FPG) levels by the end of week 1 and in mean HbA(1c) levels by week 8 in each MER+S group (both, P < 0.001). The mean (95% CI) changes from baseline to study end in the combined MER+S groups (HbA(1c), -0.74% [-0.85% to -0.64%]; FPG, -12.9 [-17.1 to -8.7] mg/dL) were significantly different from the sulfonylurea monotherapy group (HbA(1c), 0.08% [-0.08% to 0.25%]; FPG, 15.5 [8.2 to 22.8] mg/dL; P < 0.001). Among patients treated with MER+S, the mean (SEM) change in HbA(1c) was -1.26% (-1.44% to -1.07%) for drugnaive patients and -0.59% (-0.46% to 0.71%) for patients previously treated with metformin. There was a significant difference between treatment groups with regard to the prevalence of hypoglycemia (MER+S groups, 11.6% vs sulfonylurea monotherapy group, 4.2%; P = 0.007), but no significant difference was observed for gastrointestinal events. The most common gastrointestinal AEs were diarrhea and nausea (8.6% and 3.9%, respectively, in the combined MER+S groups; 2.8% and 1.4%, respectively, in the sulfonylurea monotherapy group).

CONCLUSIONS

The combination of QD or BID treatment with MER+S was significantly more effective in lowering HbA(1c) and glucose levels than sulfonylurea monotherapy in these adult patients with type 2 diabetes. However, a significant increase in the prevalence of hypoglycemia was observed in the MER+S treatment groups compared with the sulfonylurea monotherapy group.

Thiazolidinediones and the risk of edema: a meta-analysis

The use of thiazolidinediones (TZDs) in the management of type 2 diabetes mellitus (T2DM) has been associated with an increased risk of peripheral edema. A meta-analysis was performed to assess the overall risk for developing edema secondary to TZD. A systematic literature search was conducted using five electronic databases. All prospective, randomized, either placebo-controlled or comparative studies reporting the incidence of edema with TZD therapy were included. Odds ratios were generated by pooling estimates across the studies. The analysis included 26 studies consisting of 15,332 patients with T2DM. The pooled odds ratio for TZD induced edema was 2.26 (95% CI: 2.02-2.53). The results yielded a higher risk for developing edema with rosiglitazone (3.75 [2.70-5.20]) compared to pioglitazone (2.42 [1.90-3.08]). Concordant results persisted with calculations of the adjusted indirect estimate. This meta-analysis demonstrates at least a two-fold increase in the risk for developing edema with a TZD agent. The risk appears to be greater with rosiglitazone than with pioglitazone. Further studies are needed to explore this difference.

beta-cell failure in diabetes and preservation by clinical treatment

There is a progressive deterioration in beta-cell function and mass in type 2 diabetics. It was found that islet function was about 50% of normal at the time of diagnosis, and a reduction in beta-cell mass of about 60% was shown at necropsy. The reduction of beta-cell mass is attributable to accelerated apoptosis. The major factors for progressive loss of beta-cell function and mass are glucotoxicity, lipotoxicity, proinflammatory cytokines, leptin, and islet cell amyloid. Impaired beta-cell function and possibly beta-cell mass appear to be reversible, particularly at early stages of the disease where the limiting threshold for reversibility of decreased beta-cell mass has probably not been passed. Among the interventions to preserve or "rejuvenate" beta-cells, short-term intensive insulin therapy of newly diagnosed type 2 diabetes will improve beta-cell function, usually leading to a temporary remission time. Another intervention is the induction of beta-cell "rest" by selective activation of ATP-sensitive K+ (K(ATP)) channels, using drugs such as diazoxide. A third type of intervention is the use of antiapoptotic drugs, such as the thiazolidinediones (TZDs), and incretin mimetics and enhancers, which have demonstrated significant clinical evidence of effects on human beta-cell function. The TZDs improve insulin secretory capacity, decrease beta-cell apoptosis, and reduce islet cell amyloid with maintenance of neogenesis. The TZDs have indirect effects on beta-cells by being insulin sensitizers. The direct effects are via peroxisome proliferator-activated receptor gamma activation in pancreatic islets, with TZDs consistently improving basal beta-cell function. These beneficial effects are sustained in some individuals with time. There are several trials on prevention of diabetes with TZDs. Incretin hormones, which are released from the gastrointestinal tract in response to nutrient ingestion to enhance glucose-dependent insulin secretion from the pancreas, aid the overall maintenance of glucose homeostasis through slowing of gastric emptying, inhibition of glucagon secretion, and control of body weight. From the two major incretins, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), only the first one or its mimetics or enhancers can be used for treatment because the diabetic beta-cell is resistant to GIP action. Because of the rapid inactivation of GLP-1 by dipeptidyl peptidase (DPP)-IV, several incretin analogs were developed: GLP-1 receptor agonists (incretin mimetics) exenatide (synthetic exendin-4) and liraglutide, by conjugation of GLP-1 to circulating albumin. The acute effect of GLP-1 and GLP-1 receptor agonists on beta-cells is stimulation of glucose-dependent insulin release, followed by enhancement of insulin biosynthesis and stimulation of insulin gene transcription. The chronic action is stimulating beta-cell proliferation, induction of islet neogenesis, and inhibition of beta-cell apoptosis, thus promoting expansion of beta-cell mass, as observed in rodent diabetes and in cultured beta-cells. Exenatide and liraglutide enhanced postprandial beta-cell function. The inhibition of the activity of the DPP-IV enzyme enhances endogenous GLP-1 action in vivo, mediated not only by GLP-1 but also by other mediators. In preclinical studies, oral active DPP-IV inhibitors (sitagliptin and vildagliptin) also promoted beta-cell proliferation, neogenesis, and inhibition of apoptosis in rodents. Meal tolerance tests showed improvement in postprandial beta-cell function. Obviously, it is difficult to estimate the protective effects of incretin mimetics and enhancers on beta-cells in humans, and there is no clinical evidence that these drugs really have protective effects on beta-cells.

Effects of vildagliptin on glucose control over 24 weeks in patients with type 2 diabetes inadequately controlled with metformin

OBJECTIVE

We sought to evaluate the efficacy and safety of vildagliptin, a new dipeptidyl peptidase-4 inhibitor, added to metformin during 24 weeks of treatment in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

This was a double-blind, randomized, multicenter, parallel group study of a 24-week treatment with 50 mg vildagliptin daily (n = 177), 100 mg vildagliptin daily (n = 185), or placebo (n = 182) in patients continuing a stable metformin dose regimen (> or =1,500 mg/day) but achieving inadequate glycemic control (A1C 7.5-11%).

RESULTS

The between-treatment difference (vildagliptin-placebo) in adjusted mean change (AMDelta) +/- SE in A1C from baseline to end point was -0.7 +/- 0.1% (P < 0.001) and -1.1 +/- 0.1% (P < 0.001) in patients receiving 50 or 100 mg vildagliptin daily, respectively. The between-treatment difference in the AMDelta fasting plasma glucose (FPG) was -0.8 +/- 0.3 mmol/l (P = 0.003) and -1.7 +/- 0.3 mmol/l (P < 0.001) in patients receiving 50 or 100 mg vildagliptin daily, respectively. Adverse events (AEs) were reported by 63.3, 65.0, and 63.5% of patients receiving 50 mg vildagliptin daily, 100 mg vildagliptin daily, or placebo, respectively. Gastrointestinal AEs were reported by 9.6 (P = 0.022 vs. placebo), 14.8, and 18.2% of patients receiving 50 mg vildagliptin daily, 100 mg vildagliptin daily, or placebo, respectively. One patient in each treatment group experienced one mild hypoglycemic event.

CONCLUSIONS

Vildagliptin is well tolerated and produces clinically meaningful, dose-related decreases in A1C and FPG as add-on therapy in patients with type 2 diabetes inadequately controlled by metformin.