Glycemic durability of rosiglitazone, metformin, or glyburide monotherapy

Beta cell mass in diabetes: a realistic therapeutic target?

Beta cell deficiency underlies both type 1 and type 2 diabetes, and restoration or replacement of beta cell function is therefore the logical long-term solution to therapy. This review sets out to describe the defects in beta cell mass and function in both forms of diabetes, summarises current understanding of the underlying causes of beta cell death, and the methodological limitations of determining beta cell mass in vivo. Finally, the potential effects of current and future treatment regimens on beta cell mass and turnover are considered.

Targeting beta-cell mass in type 2 diabetes: promise and limitations of new drugs based on incretins

Progressive insulin secretory defects, due to either functional abnormalities of the pancreatic beta-cells or a reduction in beta-cell mass, are the cornerstone of type 2 diabetes. Incretin-based drugs hold the potential to improve glucose tolerance by immediate favorable effect on beta-cell physiology as well as by expanding or at least maintaining beta-cell mass, which may delay the progression of the disease. Long-term studies in humans are needed to elaborate on these effects.

Association of pioglitazone treatment with decreased bone mineral density in obese premenopausal patients with polycystic ovary syndrome: a randomized, placebo-controlled trial

OBJECTIVE

Our objective was to investigate the effect of pioglitazone on bone mineral density (BMD) and bone turnover markers in polycystic ovary syndrome (PCOS).

DESIGN AND SETTING

We conducted a randomized, placebo-controlled study at an outpatient clinic at a university hospital.

PATIENTS

Thirty premenopausal patients with PCOS and 14 age- and weight-matched healthy females participated.

INTERVENTIONS

Pioglitazone (30 mg/d) or placebo was given for 16 wk.

MAIN OUTCOME MEASURES

Measurements of BMD [hip (neck and total) and lumbar spine (L2-L4)], bone metabolic parameters [alkaline phosphatase (ALP), 25-hydroxyvitamin D, C-telopeptide of type I collagen (ICTP), osteocalcin, and PTH], endocrine profiles (testosterone, estradiol, and insulin), and body composition (waist to hip ratio, body mass index, and whole-body dual-energy x-ray absorptiometry scans) were performed.

RESULTS

Patients with PCOS had significantly higher levels of ICTP, fasting insulin, and testosterone than controls, whereas no differences were measured in ALP, PTH, body composition, or BMD. Pioglitazone treatment was followed by reduced BMD [geometric means (-2 to +2 sd)]: lumbar spine 1.140 (0.964-1.348) vs. 1.127 (0.948-1.341) g/cm(2) (average decline 1.1%) and femoral neck 0.966 (0.767-1.217) vs. 0.952 (0.760-1.192) g/cm(2) (average decline 1.4%), both P < 0.05. Both ALP and PTH decreased significantly during pioglitazone treatment, whereas no significant changes were measured in 25-hydroxyvitamin D, ICTP, osteocalcin, sex hormones, and body composition.

CONCLUSION

Pioglitazone treatment was followed by decreased lumbar and hip BMD and decreased measures of bone turnover in a premenopausal study population relatively protected from bone mineral loss.

Diabetes mellitus: an opportunity for therapy with stem cells?

In both Type 1 and 2 diabetes, insufficient numbers of insulin-producing beta-cells are a major cause of defective control of blood glucose and its complications. Restoration of damaged beta-cells by endocrine pancreas regeneration would be an ideal therapeutic option. The possibility of generating insulin-secreting cells with adult pancreatic stem or progenitor cells has been investigated extensively. The conversion of differentiated cells such as hepatocytes into beta-cells is being attempted using molecular insights into the transcriptional make-up of beta-cells. Additionally, the enhanced proliferation of beta-cells in vivo or in vitro is being pursued as a strategy for regenerative medicine for diabetes. Advances have also been made in directing the differentiation of embryonic stem cells into beta-cells. Although progress is encouraging, major gaps in our understanding of developmental biology of the pancreas and adult beta-cell dynamics remain to be bridged before a therapeutic application is made possible.

Dagenais GR, Gerstein HC, Holman R, Budaj A, Escalante A, Hedner T, Keltai M, Lonn E, McFarlane S, McQueen M, Teo K, Sheridan P, Bosch J, Pogue J, Yusuf S. Effects of ramipril and rosiglitazone on cardiovascular and renal outcomes in people with impaired glucose tolerance or impaired fasting glucose: results of the Diabetes REduction Assessment with ramipril and rosiglitazone Medication (DREAM) trial

OBJECTIVE

Impaired glucose tolerance (IGT) and/or impaired fasting glucose (IFG) are risk factors for diabetes, cardiovascular disease (CVD), and kidney disease. We determined the effects of ramipril and rosiglitazone on combined and individual CVD and renal outcomes in people with IGT and/or IFG in the Diabetes REduction Assessment With ramipril and rosiglitazone Medication (DREAM) trial.

RESEARCH DESIGN AND METHODS

A total of 5,269 people aged >or=30 years, with IGT and/or IFG without known CVD or renal insufficiency, were randomized to 15 mg/day ramipril versus placebo and 8 mg/day rosiglitazone versus placebo. A composite cardiorenal outcome and its CVD and renal components were assessed during the 3-year follow-up.

RESULTS

Compared with placebo, neither ramipril (15.7% [412 of 2,623] vs. 16.0% [424 of 2,646]; hazard ratio [HR] 0.98 [95% CI 0.84-1.13]; P = 0.75) nor rosiglitazone (15.0% [394 of 2,635] vs. 16.8% [442 of 2,634]; 0.87 [0.75-1.01]; P = 0.07) reduced the risk of the cardiorenal composite outcome. Ramipril had no impact on the CVD and renal components. Rosiglitazone increased heart failure (0.53 vs. 0.08%; HR 7.04 [95% CI 1.60-31.0]; P = 0.01) but reduced the risk of the renal component (0.80 [0.68-0.93]; P = 0.005); prevention of diabetes was independently associated with prevention of the renal component (P < 0.001).

CONCLUSIONS

Ramipril did not alter the cardiorenal outcome or its components. Rosiglitazone, which reduced diabetes, also reduced the development of renal disease but not the cardiorenal outcome and increased the risk of heart failure.

Rosiglitazone-associated fractures in type 2 diabetes: an Analysis from A Diabetes Outcome Progression Trial (ADOPT)

OBJECTIVE

The purpose of this study was to examine possible factors associated with the increased risk of fractures observed with rosiglitazone in A Diabetes Outcome Progression Trial (ADOPT).

RESEARCH DESIGN AND METHODS

Data from the 1,840 women and 2,511 men randomly assigned in ADOPT to rosiglitazone, metformin, or glyburide for a median of 4.0 years were examined with respect to time to first fracture, rates of occurrence, and sites of fractures.

RESULTS

In men, fracture rates did not differ between treatment groups. In women, at least one fracture was reported with rosiglitazone in 60 patients (9.3% of patients, 2.74 per 100 patient-years), metformin in 30 patients (5.1%, 1.54 per 100 patient-years), and glyburide in 21 patients (3.5%, 1.29 per 100 patient-years). The cumulative incidence (95% CI) of fractures in women at 5 years was 15.1% (11.2-19.1) with rosiglitazone, 7.3% (4.4-10.1) with metformin, and 7.7% (3.7-11.7) with glyburide, representing hazard ratios (95% CI) of 1.81 (1.17-2.80) and 2.13 (1.30-3.51) for rosiglitazone compared with metformin and glyburide, respectively. The increase in fractures with rosiglitazone occurred in pre- and postmenopausal women, and fractures were seen predominantly in the lower and upper limbs. No particular risk factor underlying the increased fractures in female patients who received rosiglitazone therapy was identified.

CONCLUSIONS

Further investigation into the risk factors and underlying pathophysiology for the increased fracture rate in women taking rosiglitazone is required to relate them to preclinical data and better understand the clinical implications of and possible interventions for these findings.

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.

Belonging to a diabetes patients' association is predictive of better metabolic control

AIM

Diabetes mellitus (DM) management requires the patient's involvement, but it is unknown whether belonging to a patient's association leads to better metabolic control.

METHODS

A total of 323 type 1 (T1) and 494 type 2 (T2) outpatient diabetics were analyzed according to whether or not they were members of a diabetes patients' association.

RESULTS

T1 members (M; N=138) were older and had longer diabetes durations than non-members (nM; N=185). Both groups had similar BP, kidney function, lipid profile, BMI and socioeducational status. HbA(1c) (means+/-SD) were lower in M than in nM: 8.1+/-1.2% versus 8.4+/-1.4%, respectively; P<0.04. T1M practised more frequent self-monitoring of blood glucose (SMBG). T2M (N=97) were also older and had longer diabetes durations than nM (N=397), and both groups had similar BP, kidney function, BMI and socioeducational status. Although M had lower HOMA beta-cell function (50.6+/-31.5% versus 63.5+/-44.3%; P<0.01), they had a similar HbA(1c) and a better lipid profile. T2M practised more frequent SMBG and were more likely to use insulin. Oral antidiabetic, antihypertensive and dyslipidaemic drug use was also similar, except for a higher use of calcium-channel blockers in T2M.

CONCLUSION

Belonging to a patients' organization was associated with better HbA(1c) in T1DM. In T2DM, which progresses relentlessly, similar HbA(1c) levels and better lipid profiles were observed, despite longer known disease durations and lower beta-cell function. These were not explained by gender, clinical, renal, therapeutic or educational parameters, but might reflect more responsibility, empowerment and/or compliance in terms of the condition or its management.

Pharmacogenomics of metabolic effects of rosiglitazone

INTRODUCTION

Thiazolidinediones are increasingly used drugs for the treatment of Type 2 diabetes. The individual response to thiazolidinedione therapy, ranging from the variable degree of metabolic improvement to harmful side-effects, is empirical, yet the underlying mechanisms remain elusive. In order to assess the pharmacogenomic component of thiazolidinediones' metabolic action, we compared the effect of rosiglitazone in two genetically defined models of metabolic syndrome, polydactylous (PD) and BN.SHR4 inbred rat strains, with their insulin-sensitive, normolipidemic counterpart, the Brown Norway (BN) rat.

MATERIALS & METHODS

5-month-old male rats were fed a high-fat diet for 4 weeks, and the experimental groups received rosiglitazone (0.4 mg/100 g body weight) during the last 2 weeks of high-fat diet feeding. We assessed metabolic and morphometric profiles, oxidative stress parameters and gene expression in white adipose tissue.

RESULTS

In many followed parameters, we observed genetic background-specific effects of rosiglitazone administration. The mass and the sensitivity of visceral adipose tissue to insulin-stimulated lipogenesis increased with rosiglitazone treatment only in PD, correlating with a PD-specific significant increase in expression of prostaglandin D2 synthase. The glucose tolerance was enhanced in all strains, although fasting plasma glucose was increased by rosiglitazone in BN and BN.SHR4. Among the markers of lipid peroxidation, we observed the rosiglitazone-driven increase of plasma-conjugated dienes only in BN.SHR4. The genes with genotype-specific expression change included ADAM metallopeptidase domain 7, aquaporin 9, carnitine palmitoyltransferase 1B, caveolin 1, catechol-O-methyl transferase, leptin and prostaglandin D2 synthase 2.

CONCLUSION

Rosiglitazone's effects on lipid deposition and insulin sensitivity of peripheral tissues are largely dependent on the genetic background it acts upon.

Too much of a good thing: why it is bad to stimulate the beta cell to secrete insulin

In many countries, first- or second-line pharmacological treatment of patients with type 2 diabetes consists of sulfonylureas (such as glibenclamide [known as glyburide in the USA and Canada]), which stimulate the beta cell to secrete insulin. However, emerging evidence suggests that forcing the beta cell to secrete insulin at a time when it is struggling to cope with the demands of obesity and insulin resistance may accelerate its demise. Studies on families with persistent hyperinsulinaemic hypoglycaemia of infancy (PHHI), the primary defect of which is hypersecretion of insulin, have shown that overt diabetes can develop later in life despite normal insulin sensitivity. In addition, in vitro experiments have suggested that reducing insulin secretion from islets isolated from patients with diabetes can restore insulin pulsatility and improve function. This article will explore the hypothesis that forcing the beta cell to hypersecrete insulin may be counterproductive and lead to dysfunction and death via mechanisms that may involve the endoplasmic reticulum and oxidative stress. We suggest that, in diabetes, therapeutic approaches should be targeted towards relieving the demand on the beta cell to secrete insulin.

Defining the role of repaglinide in the management of type 2 diabetes mellitus: a review

Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia due to a combination of insulin resistance and impaired insulin secretion. The hyperglycemia is associated with an increased risk for micro- and macrovascular complications, and lowering fasting and postprandial hyperglycemia may be protective against these complications. Repaglinide is an insulin secretagogue that lowers blood glucose levels in patients with T2DM. We review the effects of repaglinide in patients with T2DM, its impact on glycemia and its non-glycemic effects, and its effects when used in special situations or patient populations. Results from randomized controlled trials, observational studies, and safety reports involving humans and published in the English-language through 1 May 2007 identified by a search in PubMed/MEDLINE were evaluated. Present knowledge indicates that repaglinide reduces fasting and postprandial hyperglycemia and the level of glycosylated hemoglobin (HbA1c) in patients with T2DM. It is at least as effective in reducing HbA1c and fasting plasma glucose as sulphonylureas, metformin, or the glitazones and in combination therapy with other drugs, repaglinide is as effective as any other combination. Some studies show a better effect of repaglinide on postprandial glycemia than the comparators. Its propensity to induce hypoglycemia is similar to or a little less than that of sulphonylureas. Repaglinide is associated with less weight gain than sulphonylureas and the glitazones. Repaglinide has primarily a role in the treatment of T2DM when metformin cannot be used due to adverse effects, when metformin fails to adequately control blood glucose levels, when there is a need for flexible dosing (i.e. the elderly or during Ramadan fasting), or when there is a specific wish to lower postprandial glucose. Repaglinide may also have an advantage when an oral agent is needed in diabetic patients with renal impairment. Because of its short duration of action, repaglinide should be taken before each meal, usually at least three times a day. Although no study has investigated whether repaglinide lowers total mortality or cardiovascular endpoints, several studies indicate beneficial effects on cardiovascular surrogate endpoints, such as carotid intima-media thickening, markers of inflammation, platelet activation, lipid parameters, endothelial function, adiponectin, and oxidative stress. In conclusion, repaglinide is a compound that can be used in both mono- and combination therapy for the treatment of both fasting and postprandial hyperglycemia in patients with T2DM. It can be used in patients at different stages of the disease, from uncomplicated to severe renal impairment. Although the drug has been tested in a large number of clinical trials and observational studies, its world-wide use is far less than, for example, sulphonylureas. Repaglinide may offer an additional potential for lowering blood glucose levels in T2DM that until now has not been fully realized by many clinicians.

Insulin-sensitizing antihyperglycaemic medications are associated with better outcome in patients with diabetes undergoing cardiac stress testing

BACKGROUND

There are several treatment modalities available for diabetes; however, the effects of the different medications on coronary artery disease are less understood. The purpose of this study was to evaluate the correlation of insulin-sensitizing therapy with the outcome of stress myocardial perfusion testing and to compare it with conventional therapy.

METHODS

Of 417 patients referred to stress testing for evaluation of chest pain, 222 were identified as being treated with conventional therapy only (insulin and insulin secretagogues) and 195 as being treated with insulin sensitizers (metformin and thiazolidinediones (TZD)). Multivariate logistic regression models were used to correct for confounding factors and to determine the independent relation between treatment type and stress-test outcome.

RESULTS

Ischaemia, infarction and the composite outcome were less frequent in the insulin-sensitizer group than in the conventional therapy group (odds ratio (OR) = 0.39, P = 0.025; OR = 0.32, P = 0.021 and OR = 0.38, P = 0.009, respectively). The subgroup analysis showed that treatment with metformin (n = 125) compared with conventional therapy was associated with less infarction or the composite outcome of ischaemia and/or ischaemia (OR = 0.18 (95% confidence interval (CI): 0.05-0.66), P = 0.010; OR = 0.34 (95%CI: 0.15-0.80), P = 0.014, respectively). Treatment with TZD (n = 43) was associated with a trend to less frequent ischaemia (OR = 0.18 (95%CI: 0.03-1.01), P = 0.051).

CONCLUSION

The addition of insulin-sensitizing medications to the conventional diabetes therapy or their sole use was associated with decreased coronary artery disease or its severity in patients with diabetes as determined by stress myocardial perfusion study. Randomized prospective trials will be necessary to prove this benefit.

The rough road for rosiglitazone

PURPOSE OF REVIEW

Rosiglitazone is effective in lowering blood sugars in patients with type 2 diabetes and may be expected to reduce microvascular complications associated with hyperglycemia. Whereas preliminary studies using surrogate outcomes for cardiovascular disease have suggested the potential for cardioprotective effects, the drug is associated with fluid retention and increased risk of congestive heart failure. Long-term cardiovascular safety remains incompletely understood. In this review the potential for increased ischemic cardiovascular risk associated with rosiglitazone use is discussed.

RECENT FINDINGS

Meta-analysis of patients participating in controlled clinical trials suggests increased risk of cardiovascular events for patients using rosiglitazone. Considering only clinical trials in patients with type 2 diabetes with patient-level data, a double-masked, randomized design, and using approved doses of rosiglitazone, independent meta-analysis shows that cardiovascular event rates are low, and suggests that increased ischemic cardiovascular risk may be particularly manifest in subgroups of patients with type 2 diabetes who are using nitrates or insulin.

SUMMARY

There continues to be uncertainty about the risk of ischemic heart disease in patients with type 2 diabetes associated with the use of rosiglitazone. Caution should be used in patients with underlying heart disease using nitrates, and when added to ongoing insulin-based therapy.

PPARgamma agonists and coronary atherosclerosis

The prevalence of type 2 diabetes mellitus (T2DM) is growing at an alarming rate and reaching epidemic proportions, and cardiovascular disease continues to be one of the leading causes of death in the United States. The key relationship between these two diseases (knowing that T2DM is a strong risk factor for cardiovascular disease) is insulin resistance and the detrimental effect it has on macrovasculature. Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor gammaagonists that are beneficial in the treatment of T2DM and have the added benefit of modifying lipid profiles. This review discusses the basic science linking insulin resistance to atherosclerosis and describes the major TZD trials in the recent literature. It also addresses the clinical implications of these studies and media scrutiny surrounding the recent controversial report that TZDs may be linked to an increased risk of myocardial infarction.

Effects of the thiazolidinedione medications on micro- and macrovascular complications in patients with diabetes--update 2008

INTRODUCTION

The thiazolidinedione (TZD) drugs, including pioglitazone (Actos) and rosiglitazone (Avandia), are commonly prescribed in patients with type 2 diabetes mellitus (T2DM), largely due to their favorable effects on hyperglycemia, insulin sensitivity, and cardiometabolic profile. However, the data are sparse assessing the effects of TZDs on micro- and macrovascular disease risk.

DISCUSSION

Although no studies have been published on microvascular clinical outcomes, both TZDs significantly reduce the urine albumin-to-creatinine ratio. TZDs have consistently been associated with favorable effects on atherosclerosis and cardiovascular disease (CVD) risk. Only one study has been published to date specifically designed to assess the effects of a TZD (pioglitazone) on macrovascular outcomes, the PROactive trial. In this trial, pioglitazone versus placebo was associated with a non-significant 10% reduction in the combined primary endpoint of mortality, coronary and peripheral vascular events, and revascularizations. No individual trial has been published specifically assessing the CVD effects of rosiglitazone, but several meta-analyses and a published interim report from an ongoing trial (RECORD) point to safety concerns regarding rosiglitazone use and the risk of myocardial infarctions (MI), leading to amplified warnings in the product labeling for rosiglitazone to reflect these concerns.

CONCLUSION

All published trials and meta-analyses of TZDs have consistently shown increased risk of heart failure (HF) with both TZDs, though the actual placebo-subtracted incidence of HF is low (<0.5% per year). The initiation of either TZD is contraindicated in patients with NHYA class III or IV HF, and cautions exist for their use in any patient with heart failure. Much uncertainty remains regarding the aggregate CVD effects of the TZDs, and several trials are presently underway to further address these issues.

Meta-analysis of rare events: an update and sensitivity analysis of cardiovascular events in randomized trials of rosiglitazone

Background A meta-analysis of randomized controlled trials suggested that rosiglitazone, a drug used for the treatment of diabetes, may be associated with an increased risk of cardiovascular adverse events. Three large randomized trials, designed specifically to address cardiovascular outcomes of rosiglitazone treatment, have published new or updated results.

Purpose To provide a cumulative summary of the clinical trial evidence on rosiglitazone along with a sensitivity analysis of different methods to estimate the combined effect. Methods A previous meta-analysis (N Engl J Med 2007; 356: 2457—2471) was updated to include event rates of myocardial infarction and death due to cardiovascular causes from the recent reports of the RECORD, DREAM and ADOPT trials. Odds ratios (OR) with their confidence intervals were calculated for all outcomes using the Mantel—Haenszel method with Robins—Breslow—Greenland variance estimation and a fixed effects model. Sensitivity analysis was performed, using different methods for estimating the combined effect and using different continuity corrections for studies with zero events in one or both arms.

Results Rosiglitazone was associated with an increased risk of myocardial infarction (OR, 1.29; CI: 1.01—1.66; p = 0.05) but not death due to cardiovascular causes (OR, 1.12; CI: 0.80—1.55; p = 0.58). Pooled analysis of the ADOPT, RECORD, and DREAM trials did not reach statistical significance for either myocardial infarction (OR, 1.29; CI: 0.95—1.74; p = 0.12) or death due to cardiovascular causes (OR, 0.90; CI: 0.61—1.33; p = 0.67). Based on these three trials, rosiglitazone was associated with a clear increase in the risk of heart failure (OR, 2.17; CI: 1.49—3.17; p<0.0001). Despite minor discrepancies, different calculation methods demonstrated an increased risk of myocardial infarction for rosiglitazone treated patients. There was no evidence of an association between rosiglitazone and death due to cardiovascular causes regardless of the calculation method used. The increased risk of heart failure conferred by rosiglitazone treatment was consistently demonstrated across different calculation methods.

Limitations Trials with short-term follow-up and trials not specifically designed to evaluate cardiovascular outcomes were included in this meta-analysis and patient-level data where not available.

Conclusions Rosiglitazone appears to be associated with an increased risk of myocardial infarction and heart failure, but not death due to cardiovascular causes. When a meta-analysis of rare events is contemplated, a thorough sensitivity analysis using different methods to combine studies and an evaluation of different continuity corrections should be undertaken. When possible, an individual patient data meta-analysis should be performed, allowing time-to-event analysis and the identification of patient subgroups at an increased risk of adverse outcomes. Clinical Trials 2008; 5: 116—120. http://ctj.sagepub.com

Cholesterol in islet dysfunction and type 2 diabetes

Type 2 diabetes (T2D) frequently occurs in the context of abnormalities of plasma lipoproteins. However, a role for elevated levels of plasma cholesterol in the pathogenesis of this disease is not well established. Recent evidence suggests that alterations of plasma and islet cholesterol levels may contribute to islet dysfunction and loss of insulin secretion. A number of genes involved in lipid metabolism have been implicated in T2D. Recently an important role for ABCA1, a cellular cholesterol transporter, has emerged in regulating cholesterol homeostasis and insulin secretion in pancreatic beta cells. Here we review the impact of cholesterol metabolism on islet function and its potential relationship to T2D.

Prevention of Type 2 diabetes: fact or fiction?

The growing prevalence of Type 2 diabetes with its high morbidity and excess mortality is imposing a heavy burden on healthcare systems. Because of the magnitude of the problem, obviating diabetes has been a long-standing dream. In the last decade, a number of intervention strategies have been shown to be effective for the prevention of diabetes in high-risk populations with prediabetes. Seven studies have now confirmed that lifestyle modifications, including weight-reducing diets and exercise programs, are very effective in precluding or delaying Type 2 diabetes in high-risk populations with impaired glucose tolerance (IGT). Two major trials are the Diabetes Prevention Study (n = 522) from Finland and the Diabetes Prevention Program (n = 3234) from the US. Both studies have shown that intensive lifestyle intervention could reduce the progression of IGT to diabetes by 58%. Furthermore, four currently-available drugs have been established as being effective in preventing diabetes in subjects with prediabetes. The Diabetes Prevention Program revealed that metformin 850 mg b.i.d. reduced the risk of diabetes by 31%. The STOP-NIDDM (Study To Prevent Non-Insulin-Dependent Diabetes Mellitus) trial (n = 1429) showed that acarbose 100 mg t.i.d. with meals decreased the incidence of diabetes by 36% when the diagnosis was based on 2 oral glucose tolerance tests. The XENDOS (Xenical in the Prevention of Diabetes in Obese Subjects) study examined the use of orlistat, an antiobesity drug, as an adjunct to an intensive lifestyle modification program in obese non-diabetic subjects. Orlistat treatment resulted in a 37% decline in the development of diabetes. More recently, the DREAM (Diabetes Reduction Assessment with Ramipril and Rosiglitazone Medication) study (n = 5269) demonstrated that rosiglitazone at 8 mg once/day in subjects with prediabetes (IGT and/or impaired fasting glucose) was effective in reducing the risk of diabetes by 60%. It can be concluded that Type 2 diabetes can be prevented or delayed through lifestyle modifications and/or pharmacologic interventions. This is a fact.

Osteoporosis among patients with type 1 and type 2 diabetes

Both diabetes and fractures are prevalent in adults. The relationship between diabetes and osteoporosis is complex and, although it has been investigated extensively, the subject remains controversial. While low bone mineral density (BMD) is consistently observed in type 1 diabetes, the relationship is less clear in type 2 diabetes, with some studies reporting modestly increased or unchanged BMD. Both type 1 and type 2 diabetes have been associated with a higher risk of fractures. Despite discrepancies between BMD and fracture rates, clinical trials uniformly support the fact that new bone formation and bone microarchitecture and, thus, bone quality, are altered in both types of diabetes. Although a causal association between diabetes and osteoporosis cannot be established on the basis of existing data, it is possible to conclude from many studies and from a better understanding of the physiopathology of diabetes that it can increase the risk of fractures through skeletal (decreased BMD and bone quality) and extraskeletal (increased risk of falls) factors. Even though osteoporosis screening or prophylactic treatment in all patients with type 1 and type 2 diabetes is not being recommended at present, such patient populations should be given general guidelines regarding calcium and vitamin D intakes, exercise and the avoidance of potential risk factors for osteoporosis. The extent of diagnostic and therapeutic interventions should be based on the individual's risk profile for fractures.

The association between hyperglycemia and fracture risk in middle age. A prospective, population-based study of 22,444 men and 10,902 women

AIMS

Type 1 diabetes mellitus is associated with increased fracture risk, whereas the risk associated with type 2 diabetes is less obvious. Elevated fasting blood glucose and high 2-h glucose during an oral glucose tolerance test indicate impaired glucose tolerance or diabetes. The associations among fasting blood glucose, 2-h glucose, and the risk of fracture were investigated.

METHODS

The Malmö Preventive Project consists of 22,444 men (44+/-6.6 yr) and 10,902 women (50+/-7.4 yr), with a follow-up of 19 yr (+/-3.9) and 15 yr (+/-4.5) for incident fractures. Baseline assessment included multiple examinations and lifestyle information. A logistic regression model was used. Adjustments were made for age, body mass index (BMI), and smoking.

RESULTS

Low-energy fractures were recorded in 1246 men and 1236 women. A 2-h glucose measurement between 4.3 and 6.2 mmol/liter in men (second and third quartile), and above 6.5 mmol/liter in women (third and fourth quartile), adjusted for age, BMI, and smoking, was significantly associated with a decreased risk of multiple fractures, in men [odds ratios (ORs) 0.57-0.71] and women (ORs 0.38-0.66). In women, a 2-h glucose measurement above 7.5 mmol/liter was associated with a decreased risk of osteoporotic fractures (OR 0.57, 95% confidence interval 0.44-0.74).

CONCLUSIONS

In middle-aged men and women, elevated 2-h glucose levels were associated with decreased risks of multiple and osteoporotic fractures, independent of age, BMI, and smoking. A high 2-h glucose level is characterized by peripheral insulin resistance with a high insulin level. Our findings indirectly suggest a positive effect on bone from hyperglycemia.

PPAR gamma: ally and foe in bone metabolism

Bone homeostasis is a well-balanced process that is largely dependent on the contribution of both bone-forming osteoblasts and bone-resorbing osteoclasts. A new study (Wan et al., 2007) suggests a previously unsuspected role for the transcription factor PPARgamma in promoting bone progenitors to the osteoclastic lineage.

Effect of aging on glucose homeostasis: accelerated deterioration of beta-cell function in individuals with impaired glucose tolerance

OBJECTIVE

To examine the effect of aging on insulin secretion (first- and second-phase insulin release) and insulin sensitivity in people with normal glucose tolerance (NGT) or impaired glucose tolerance (IGT).

RESEARCH DESIGN AND METHODS

First- and second-phase insulin secretion and insulin sensitivity were assessed in hyperglycemic clamp experiments in 266 individuals with NGT and 130 individuals with IGT, ranging in age from approximately 20 to approximately 70 years. Changes in beta-cell function were compared using the disposition index to adjust for differences in insulin sensitivity.

RESULTS

As expected, both phases of insulin release and insulin sensitivity were reduced in individuals with IGT (all P < 0.01). Insulin sensitivity was not independently correlated with age in either group. In people with NGT, the disposition index for first- and second-phase insulin release decreased similarly at a rate of approximately 0.7% per year. In people with IGT, the disposition indexes for first- and second-phase insulin release decreased at greater rates ( approximately 2.2 and 1.4% per year, P = 0.002 and 0.009, respectively, vs. NGT), with the decrease in first phase being greater than that of second phase (P = 0.025).

CONCLUSIONS

Insulin secretion (both first and second phase) normally decreases at a rate of approximately 0.7% per year with aging; this decrease in beta-cell function is accelerated about two-fold in people with impaired glucose tolerance-first phase to a greater extent than second phase. Finally, aging per se has no effect on insulin sensitivity independent of changes in body composition.

Rosiglitazone for active ulcerative colitis: a randomized placebo-controlled trial

BACKGROUND & AIMS

Thiazolidinedione ligands for the gamma subtype of peroxisome proliferator-activated receptors (PPARgamma), widely used to treat type 2 diabetes mellitus, have been proposed as novel therapies for ulcerative colitis (UC).

METHODS

This multicenter, randomized, double-blind, placebo-controlled clinical trial compared the efficacy of rosiglitazone (Avandia; GlaxoSmithKline, Philadelphia, PA) 4 mg orally twice daily vs placebo twice daily for 12 weeks in 105 patients with mild to moderately active UC. Disease activity was measured with the Mayo score. The primary end point was clinical response (>/=2-point reduction) at week 12. Clinical remission (Mayo score

RESULTS

After 12 weeks of therapy, 23 patients (44%) treated with rosiglitazone and 12 patients (23%) treated with placebo achieved clinical response (P = .04). Remission was achieved in 9 patients (17%) treated with rosiglitazone and 1 patient (2%) treated with placebo (P = .01). Endoscopic remission was uncommon in either treatment arm (8% rosiglitazone vs 2% placebo; P = .34). Clinical improvement was evident as early as 4 weeks after beginning treatment (P = .049). Quality of life was improved significantly at week 8 (P = .01), but not at week 4 (P = .48) or week 12 (P = .14). Serious adverse events were rare.

CONCLUSIONS

Rosiglitazone was efficacious in the treatment of mild to moderately active UC.

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Key Words Collapse

MESH Headings

• Administration, Oral
• Adult
• Anti-Inflammatory Agents/administration & dosage
• Anti-Inflammatory Agents/adverse effects
• Anti-Inflammatory Agents/therapeutic use
• Colitis, Ulcerative/drug therapy
• Colitis, Ulcerative/pathology
• Colonoscopy
• Double-Blind Method
• Drug Administration Schedule
• Female
• Gastrointestinal Agents/administration & dosage
• Gastrointestinal Agents/adverse effects
• Gastrointestinal Agents/therapeutic use
• Humans
• Male
• Middle Aged
• Patient Selection
• Quality of Life
• Rosiglitazone
• Severity of Illness Index
• Sigmoidoscopy
• Thiazolidinediones/administration & dosage
• Thiazolidinediones/adverse effects
• Thiazolidinediones/therapeutic use
• Time Factors
• Treatment Outcome
• United States

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Grants

• R01 DK059961 NIDDK NIH HHS
• DK059961 NIDDK NIH HHS

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Affiliation(s)

James D Lewis Division of Gastroenterology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
Gary R Lichtenstein
Julius J Deren
Bruce E Sands
Stephen B Hanauer
Jeffrey A Katz
Bret Lashner
Daniel H Present
Shaokun Chuai
Jonas H Ellenberg
Lisa Nessel
Gary D Wu
Rosiglitazone for Ulcerative Colitis Study Group

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Collaborators Collapse

Preserving insulin secretion in Type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a complex disease characterized by insulin resistance and a progressive decline in β-cell function and mass. Current evidence suggests that β-cell dysfunction is present early in the course of the disease and that this dysfunction, rather than insulin resistance, is primarily responsible for the progression of T2DM. β-cell dysfunction can be accelerated by glucose toxicity, lipotoxicity, oxidative stress, chronic increases in inflammatory mediators and, potentially, the use of sulfonylureas. This review suggests that future efforts to limit the impact of T2DM must focus on strategies to preserve β-cell function. Several interventions have shown promise in this regard, including lifestyle modifications, thiazolidinediones, potassium channel openers, incretin mimetics, cytokine antagonists, bariatric surgery and dipeptidyl peptidase IV inhibitors, although therapeutic insulin remains the most robust and physiological approach.

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.

Hypoglycaemia in Type 2 diabetes

The primary cause of hypoglycaemia in Type 2 diabetes is diabetes medication-in particular, those which raise insulin levels independently of blood glucose, such as sulphonylureas (SUs) and exogenous insulin. The risk of hypoglycaemia is increased in older patients, those with longer diabetes duration, lesser insulin reserve and perhaps in the drive for strict glycaemic control. Differing definitions, data collection methods, drug type/regimen and patient populations make comparing rates of hypoglycaemia difficult. It is clear that patients taking insulin have the highest rates of self-reported severe hypoglycaemia (25% in patients who have been taking insulin for > 5 years). SUs are associated with significantly lower rates of severe hypoglycaemia. However, large numbers of patients take SUs in the UK, and it is estimated that each year > 5000 patients will experience a severe event caused by their SU therapy which will require emergency intervention. Hypoglycaemia has substantial clinical impact, in terms of mortality, morbidity and quality of life. The cost implications of severe episodes-both direct hospital costs and indirect costs-are considerable: it is estimated that each hospital admission for severe hypoglycaemia costs around pound1000. Hypoglycaemia and fear of hypoglycaemia limit the ability of current diabetes medications to achieve and maintain optimal levels of glycaemic control. Newer therapies, which focus on the incretin axis, may carry a lower risk of hypoglycaemia. Their use, and more prudent use of older therapies with low risk of hypoglycaemia, may help patients achieve improved glucose control for longer, and reduce the risk of diabetic complications.

Metformin: effects on micro and macrovascular complications in type 2 diabetes

INTRODUCTION

The antihyperglycaemic agent metformin is widely used in the treatment of type 2 diabetes. Data from the UK Prospective Diabetes Study and retrospective analyses of large healthcare databases concur that metformin reduces the incidence of myocardial infarction and increases survival in these patients. This apparently vasoprotective effect appears to be independent of the blood glucose-lowering efficacy.

EFFECTS OF METFORMIN

Metformin has long been known to reduce the development of atherosclerotic lesions in animal models, and clinical studies have shown the drug to reduce surrogate measures such as carotid intima-media thickness. The anti-atherogenic effects of metformin include reductions in insulin resistance, hyperinsulinaemia and obesity. There may be modest favourable effects against dyslipidaemia, reductions in pro-inflammatory cytokines and monocyte adhesion molecules, and improved glycation status, benefiting endothelial function in the macro- and micro-vasculature. Additionally metformin exerts anti-thrombotic effects, contributing to overall reductions in athero-thrombotic risk in type 2 diabetic patients.

[Lights and shades in the application of new guidelines for the management of type 2 diabetes mellitus. Practical advice about combined therapy and insulin therapy]

Type 2 diabetes is a disease with an increasing prevalence due to the ageing and sedentary lifestyle of the general population. Its associated with the risk of developing a series of chronic complications in mid/long-term. The current guidelines recommend certain therapy targets that have proven difficult to achieve due to poor compliance or because doctors do not always adhere to expert guidelines. The inability to achieve an adequate glycemic control in the course of diabetes may result in part from the typical conservative stepwise treatment approach that includes monotherapy initiated alter failure of diet and exercise, followed by a combination of oral antiglycemic agents, and ultimately insulin therapy. With respect to insulin therapy, the availability of different analogues as well as the new routes of administration (e.g., inhaled insulin) may allow the early introduction of this therapy, which may be more readily accepted by the patient.

Skeletal consequences of thiazolidinedione therapy

Thiazolidinediones (TZDs) are agonists of the peroxisome proliferator-activated receptor gamma (PPARgamma) nuclear transcription factor. Two members of this drug class, rosiglitazone and pioglitazone, are commonly used in the management of type II diabetes mellitus, and play emerging roles in the treatment of other clinical conditions characterized by insulin resistance. Over the past decade, a consistent body of in vitro and animal studies has demonstrated that PPARgamma signaling regulates the fate of pluripotent mesenchymal cells, favoring adipogenesis over osteoblastogenesis. Treatment of rodents with TZDs decreases bone formation and bone mass. Until recently, there were no bone-related data available from studies of TZDs in humans. In the past year, however, several clinical studies have reported adverse skeletal actions of TZDs in humans. Collectively, these investigations have demonstrated that the TZDs currently in clinical use decrease bone formation and accelerate bone loss in healthy and insulin-resistant individuals, and increase the risk of fractures in the appendicular skeleton in women with type II diabetes mellitus. These observations should prompt clinicians to evaluate fracture risk in patients for whom TZD therapy is being considered, and initiate skeletal protection in at-risk individuals.

Bone fractures and hypoglycemic treatment in type 2 diabetic patients: a case-control study

OBJECTIVE

Hypoglycemic treatments could modulate the risk for fractures in many ways. Most studies have not explored the effect on the incidence of bone fractures of individual oral hypoglycemic agents, rather all oral treatments as a whole. The aim of this case-control study, nested within a retrospective cohort, is the assessment of the risk for bone fractures associated with exposure to insulin or different oral hypoglycemic agents.

RESEARCH DESIGN AND METHODS

A case-control study nested within a cohort of 1,945 diabetic outpatients with a follow-up of 4.1 +/- 2.3 years was performed, comparing 83 case subjects of bone fractures and 249 control subjects matched for age, sex, duration of diabetes, BMI, A1C, comorbidity, smoking, and alcohol abuse. Exposure to hypoglycemic drugs during the 10 years preceding the event (or matching index date) was assessed.

RESULTS

In a model including treatment with insulin secretagogues metformin and insulin for at least 36 months during the previous 10 years, no significant association was observed between bone fractures and medications. In an alternative model considering treatments at the time of fracture, insulin treatment was significantly associated with bone fractures in men (OR 3.20 [95% CI 1.32-7.74]) but not in women (1.41 [0.73-2.73]).

CONCLUSIONS

Insulin-sensitizing treatment with metformin is not associated with a higher incidence of bone fractures, suggesting that the negative effect of thiazolidinediones is due to a specific action on bone metabolism rather a reduction of insulinemia. Conversely, current treatment with insulin increases the risk of fractures; at the same time, exposure to this agent in the longer term does not appear to affect bone frailty.

Drugs acting on SUR1 to treat CNS ischemia and trauma

Sulfonylurea receptor 1 (SUR1) is a molecule with more diverse and critically important functions than previously recognized. Long viewed simply as a subunit involved in formation of a subset of K(ATP) channels, accumulating evidence indicates that SUR1 is newly upregulated in CNS ischemia and injury and is surprisingly promiscuous in its association with different pore-forming subunits, which endow it with new roles not previously envisioned. In this review, we focus on the SUR1-regulated NC(Ca-ATP) channel, its emerging role in CNS ischemia and trauma, and the growing evidence from preclinical and clinical studies demonstrating the potential importance of block of SUR1 by sulfonylureas such as glibenclamide (glyburide) in conditions as seemingly diverse as stroke and spinal cord injury.

The murine glucagon-like peptide-1 receptor is essential for control of bone resorption

Gastrointestinal hormones including gastric inhibitory polypeptide (GIP), glucagon-like peptide (GLP)-1, and GLP-2 are secreted immediately after meal ingestion, and GIP and GLP-2 have been shown to regulate bone turnover. We hypothesize that endogenous GLP-1 may also be important for control of skeletal homeostasis. We investigated the role of GLP-1 in the regulation of bone metabolism using GLP-1 receptor knockout (Glp-1r(-/-)) mice. A combination of bone density and histomorphometry, osteoclast activation studies, biochemical analysis of calcium and PTH, and RNA analysis was used to characterize bone and mineral homeostasis in Glp-1r(-/-) and Glp-1r(+/+) littermate controls. Glp-1r(-/-) mice have cortical osteopenia and bone fragility by bone densitometry as well as increased osteoclastic numbers and bone resorption activity by bone histomorphometry. Although GLP-1 had no direct effect on osteoclasts and osteoblasts, Glp-1r(-/-) mice exhibited higher levels of urinary deoxypyridinoline, a marker of bone resorption, and reduced levels of calcitonin mRNA transcripts in the thyroid. Moreover, calcitonin treatment effectively suppressed urinary levels of deoxypyridinoline in Glp-1r(-/-), mice and the GLP-1 receptor agonist exendin-4 increased calcitonin gene expression in the thyroid of wild-type mice. These findings establish an essential role for endogenous GLP-1 receptor signaling in the control of bone resorption, likely through a calcitonin-dependent pathway.

Effects of ABCA1 variants on rosiglitazone monotherapy in newly diagnosed type 2 diabetes patients

AIM

The aim of the present study was to investigate the relationship between R219K, M883I, and R1587K variants of the ATP-binding cassette transporter subfamily A number 1 (ABCA1) gene and response to rosiglitazone treatment in newly diagnosed patients with type 2 diabetes.

METHODS

A total of 105 diabetic patients with no history of antihyperglycemia medication were treated with rosiglitazone (4 or 8 mg daily) for 48 weeks. Three non-synonymous variants R219K, M883I, and R1587K, were genotyped in all patients.

RESULTS

Ninety-three patients completed the entire study. The R219K variant of ABCA1 had an effect on rosiglitazone response with the per-allele odds ratio of 2.04 for treatment failure (P<0.05). The RR homozygotes had a better improvement in indicators of insulin sensitivity, as determined by a significantly greater decrease in the homeostasis model assessment index of insulin resistance (-2.39+/-0.46 vs -0.69+/-0.51, P<0.05). No genotype-phenotype association was detected for M883I and R1587K.

CONCLUSION

The R219K variant of ABCA1 was associated with the therapeutic effect of rosiglitazone. The RR homozygotes had a better response to rosiglitazone treatment in terms of insulin sensitivity improvement than minor K allele carriers. Neither the M883I nor R1587K variant of the ABCA1 gene was associated with rosiglitazone response.

Comparison of different drugs as add-on treatments to metformin in type 2 diabetes: a meta-analysis

BACKGROUND

Metformin is recommended as first-line treatment in type 2 diabetic patients. Several agents can be used as add-on treatments in metformin monotherapy failure. Most available clinical trials on the hypoglycemic efficacy of different drugs were performed either in monotherapy or in combination with agents other than metformin. Aim of the present meta-analysis is to collect available information on the efficacy of different hypoglycemic drugs, in combination with metformin, in patients failing to metformin, or to other oral monotherapies.

METHODS

An extensive Medline search, together with manual search of references from retrieved articles, was performed to identify randomized clinical trials comparing the efficacy on HbA1c of different agents, compared with placebo or with other active drugs, in combination with metformin, in patients failing to oral hypoglycemic therapy. HbA1c reduction at 16-36 months was considered for meta-analysis.

RESULTS

A total of 27 clinical trials were retrieved. Combining the results of different placebo-controlled trials, sulphonylureas, alpha-glucosidase inhibitors and thiazolidinediones induced a reduction [95%CI] of HbA1c of 0.85 [0.78; 0.94], 0.61 [0.55; 0.67], 0.42 [0.40; 0.44]%, respectively. In direct comparisons, sulphonylureas induced a greater reduction of HbA1c (of 0.17 [0.16; 0.18]%) than thiazolidinediones, and had a similar effect as insulin.

CONCLUSIONS

When combined with metformin, sulphonylureas and alpha-glucosidase inhibitors show a similar efficacy on HbA1c. The effects of drugs used as add-on to metformin monotherapy could be different from those observed in monotherapy.