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

Saxagliptin and sitagliptin in adult patients with type 2 diabetes: a systematic review and meta-analysis

The objective of this study is to compare the efficacy and safety of sitagliptin and saxagliptin with placebo and other hypoglycaemic medications in adults with type 2 diabetes. We searched MEDLINE®, Embase, the Cochrane Library and the International Pharmaceuticals from their inception through 3 February 2011. Studies were included of adults with type 2 diabetes that were 12 weeks or more in duration. Meta-analyses were conducted when included studies were homogenous enough to justify combining their results. A total of 32 articles met inclusion criteria. Sitagliptin 100 mg monotherapy and saxagliptin 5 mg resulted in greater HbA1c reduction compared to placebo [weighted mean difference (WMD) -0.82%, 95% CI -0.95 to -0.70 and WMD -0.70, 95% CI -0.84 to -0.56, respectively]. Sitagliptin was similar to sulfonylureas for HbA1c reduction (WMD 0.08%, 95% CI 0-0.16, 3 trials) and to saxagliptin in one head-to-head trial. There was no statistically significant difference in hypoglycaemia between sitagliptin (pooled RR 1.55, 95% CI 0.55-4.36) or saxagliptin (pooled RR 1.04, 95% CI 0.28-3.81) and placebo. Sitagliptin and saxagliptin result in similar modest HbA1c reductions and do not increase the risk of hypoglycaemia unless combined with other therapies. Their role in the long-term treatment of type 2 diabetes remains unclear given the lack of long-term data on efficacy, harms and health outcomes.

Sitagliptin add-on to low dosage sulphonylureas: efficacy and safety of combination therapy on glycaemic control and insulin secretion capacity in type 2 diabetes

AIMS

To assess the efficacy and safety of combination therapy with sitagliptin and low dosage sulphonylureas on glycaemic control and insulin secretion capacity in Japanese type 2 diabetes.

METHODS

Eighty-two subjects were sequentially recruited for the 52-week, prospective, single arm study. Sitagliptin was added on to sulphonylureas (glimepride or gliclazide) with or without metformin. The primary endpoint was a change in A1C. The secondary endpoints were changes in BMI, insulin secretion capacity, blood pressure and urinary albumin excretion, unresponsive rate, and hypoglycaemia. Insulin secretion capacity was evaluated by glucagon loading test.

RESULTS

Change in A1C was -0.80% (95% CI -0.90 to -0.68) (p < 0.001). Change in BMI, systemic and diastolic blood pressure, and urinary albumin excretion were -0.38 kg/m(2) (95% CI -0.72 to -0.04) (p < 0.05), -6.7/-3.6 mmHg (95% CI -10.0 to -3.4/-4.8 to -2.4) (p < 0.001), and -43.2 mg/gCr (95% CI -65.7 to -20.8) (p < 0.001) respectively. Mild hypoglycaemia was observed in three cases. The unresponsive rate was 6.1%. Glucagon loading test showed that 0-min and 6-min CPR at baseline and 52-week were not significantly changed: 0-min CPR, 1.58 ± 0.58-1.71 ± 0.73 ng/ml; 6-min CPR, 3.48 ± 1.47-3.58 ± 1.21 ng/ml. Insulin secretion capacity, CPI and SUIT index at baseline did not predict the efficacy of the combination therapy. The final dosages of glimepiride and gliclazide were 1.44 ± 0.90 mg and 34.5 ± 15.3 mg respectively. The dosage of sitagliptin was increased from 50 mg to 69.0 ± 24.5 mg in 52-week.

CONCLUSIONS

The combination therapy with sitagliptin and low dosage sulphonylureas was safe and effective for glycaemic control. Glucagon loading test indicated that 1 year administration of sitagliptin and sulphonylureas preserved insulin secretion capacity.

The role of self-monitoring of blood glucose in glucagon-like peptide-1-based treatment approaches: a European expert recommendation

The role of glucagon-like peptide (GLP)-1-based treatment approaches for type 2 diabetes mellitus (T2DM) is increasing. Although self-monitoring of blood glucose (SMBG) has been performed in numerous studies on GLP-1 analogs and dipeptidyl peptidase-4 inhibitors, the potential role of SMBG in GLP-1-based treatment strategies has not been elaborated. The expert recommendation suggests individualized SMBG strategies in GLP-1-based treatment approaches and suggests simple and clinically applicable SMBG schemes. Potential benefits of SMBG in GLP-1-based treatment approaches are early assessment of treatment success or failure, timely modification of treatment, detection of hypoglycemic episodes, assessment of glucose excursions, and support of diabetes management and diabetes education. Its length and frequency should depend on the clinical setting and the quality of metabolic control. It is considered to play an important role for the optimization of diabetes management in T2DM patients treated with GLP-1-based approaches.

Glucagon-like peptide 1 (GLP-1) analogue combined with insulin reduces HbA1c and weight with low risk of hypoglycemia and high treatment satisfaction

AIMS

To evaluate the effects of adding glucagon-like peptide-1 (GLP-1) analogue therapy to insulin on glycated hemoglobin (HbA1c), weight, insulin dosage, treatment satisfaction, and risk of hypoglycaemia.

METHODS

Type 2 diabetes patients with insulin therapy receiving a GLP-1 analogue at 4 Swedish centers were studied. Hypoglycemia was evaluated using glucometers and patient self-report. The Diabetes Treatment Satisfaction Questionnaire (DTSQ) was used to evaluate treatment satisfaction.

RESULTS

Among 65 patients studied, 4 discontinued therapy, none due to hypoglycemia, and there were no suspected severe adverse events. Among 61 patients who remained on therapy over a mean of 7.0 months, 40 were treated with liraglutide and 21 with exenatide. HbA1c decreased from a mean of 8.9% (82.4 mmol/mol) to 7.9% (71.9 mmol/mol) (p<0.001), weight decreased from 111.1 kg to 104.0 kg (p<0.001) and insulin doses were reduced from 91.1U to 52.2U (p<0.001). There was one patient with severe hypoglycemia. The mean number of asymptomatic hypoglycemia per patient and month, reported for the last month (0.085 below 4.0 mmol/l and 0 below 3.0 mmol/l) and documented symptomatic hypoglycemia (0.24 below 4.0 mmol/l and 0.068 below 3.0 mmol/l) was low. The DTSQc showed higher treatment satisfaction than with the previous regimen of 11.9 (scale -18 to +18 points, p<0.001).

CONCLUSIONS

The addition of GLP-1 analogues to insulin in patients with type 2 diabetes is associated with reductions in HbA1c, weight, and insulin dose, along with a low risk of hypoglycemia and high treatment satisfaction.

Effect of saxagliptin as add-on therapy in patients with poorly controlled type 2 diabetes on insulin alone or insulin combined with metformin

OBJECTIVE

To evaluate efficacy and safety of saxagliptin as add-on therapy in patients with type 2 diabetes (T2D) with inadequate glycemic control on insulin alone or combined with metformin.

METHODS

Adults (n = 455) with HbA(1c) 7.5-11% on stable insulin therapy (30-150 U/day ± metformin) for at least 8 weeks were stratified by metformin use and randomly assigned 2:1 to receive saxagliptin 5 mg or placebo once daily for 24 weeks. Patients were to maintain stable insulin doses but these could be decreased to reduce risk of hypoglycemia. Patients with hyperglycemia or substantially increased insulin use were rescued with a flexible insulin regimen and remained in the study. Metformin doses were kept stable. The primary efficacy endpoint was change in HbA(1c) from baseline to week 24 (or rescue).

RESULTS

Patients treated with saxagliptin versus placebo had significantly greater reductions in adjusted mean HbA(1c) (difference: -0.41%, p < 0.0001), postprandial glucose (PPG) 180-minute area under the curve (-3829.8 mg·min/dL, p = 0.0011), and 120-minute PPG (-23.0 mg/dL, p = 0.0016) at 24 weeks. Treatment with saxagliptin resulted in similar reductions in HBA(1c) relative to placebo, irrespective of metformin treatment. At 24 weeks, difference in adjusted mean fasting plasma glucose for saxagliptin versus placebo was -4.02 mg/dL (p = 0.3958); 17.3% and 6.7% of patients in the saxagliptin and placebo groups, respectively, achieved HbA(1c) < 7%. Mean change from baseline in body weight at week 24 was 0.39 kg for saxagliptin and 0.18 kg for placebo. Hypoglycemia was reported in 18.4% and 19.9% of patients in the saxagliptin and placebo groups, respectively (confirmed hypoglycemia: 5.3%, 3.3%). Other adverse events reported in at least 5% of patients were urinary tract infection (saxagliptin, placebo: 5.9%, 6.0%), influenza (3.0%, 6.6%), and pain in extremity (1.6%, 6.0%).

CONCLUSIONS

Saxagliptin 5-mg once-daily add-on therapy improves glycemic control in T2D patients on insulin alone or combined with metformin and is generally well-tolerated. NCT00757588.

Dipeptidyl peptidase-4 inhibitors: 3 years of experience

According to the latest American Diabetes Association guidelines, lowering glycated hemoglobin (HbA(1c)) to below or around 7% has been shown to reduce microvascular and neuropathic complications of diabetes and, if implemented soon after the diagnosis of diabetes, is associated with long-term reduction in macrovascular disease. Recently a new class of antidiabetes drugs has been developed, dipeptidyl peptidase-4 (DPP-4) inhibitors, which act by inhibiting DPP-4, the enzyme that inactivates glucagon-like peptide-1 (GLP-1). Through the inhibition of DPP-4, DPP-4 inhibitors enhance the effects of GLP-1 and glucose-dependent insulinotropic peptide, increasing glucose-mediated insulin secretion and suppressing glucagon secretion. We conducted a review analyzing clinical efficacy and safety of DPP-4 inhibitors, both alone and in combination with other antidiabetes drugs, including randomized controlled trials about sitagliptin, vildagliptin, saxagliptin, and linagliptin conducted in the latest 15 years. We concluded that, once metformin fails to maintain glycemic control, addition of DPP-4 inhibitors should be the logical choice: they seems to lower HbA(1c) levels by 0.6-0.9 percentage points and to have a comparable effect on HbA(1c) versus the addition of a sulfonylurea or glitazone. They also have positive effects on β-cell function, and they have neutral effects on body weight. Furthermore, DPP-4 inhibitors prevent the risk of hypoglycemia posed by sulfonylureas.

Liraglutide: from clinical trials to clinical practice

Liraglutide, a once-daily glucagon-like peptide-1 receptor agonist, is approved for use as monotherapy in the USA and Japan (but not in Europe or Canada) and in combination with selected oral agents (all regions) for the treatment of patients with type 2 diabetes. Guidance from local advisory bodies is emerging on the most appropriate place for liraglutide in the treatment pathway. It is apparent from its phase 3 clinical trial programme that liraglutide provides superior glycaemic control compared with that achieved with other antidiabetic agents used early in the treatment pathway (e.g. glimepiride and sitagliptin). Key additional benefits include a low incidence of hypoglycaemia and clinically relevant weight loss, although these benefits may be ameliorated by concomitant sulphonylurea (SU) treatment and, in the case of hypoglycaemia, reduction of the SU dose may be necessary. Overall, the profile of liraglutide is similar and, in some aspects, superior to twice-daily exenatide. The implementation of liraglutide therapy is straightforward, with simple dose titration from the starting dose of 0.6 to 1.2 mg/day after 1 week; some patients may benefit from additional titration to 1.8 mg/day. Treatment is self-administered by subcutaneous injection. This contrasts with other agents used early in the treatment pathway, but clinical data suggest patients' overall treatment satisfaction with liraglutide is similar (1.2 mg) or better (1.8 mg) than that with sitagliptin despite differing administration methods. Some patients may experience nausea when initiating liraglutide treatment, but the titration regimen is designed to improve tolerability and clinical data indicate nausea is transient.

Differentiating among incretin therapies: a multiple-target approach to type 2 diabetes

WHAT IS KNOWN AND OBJECTIVE

Incretin-based glucagon-like peptide-1 receptor agonists (GLP-1 RAs) and dipeptidyl peptidase-4 (DPP-4) inhibitor therapies provide glycaemic control with reduced risks associated with weight gain or hypoglycaemia. Incretin therapies are compared with their mechanisms of action, effects on haemoglobin A(1C) (HbA(1C)), fasting plasma glucose (FPG), post-prandial glucose (PPG), body weight, β-cell function, cardiovascular biomarkers and in their safety profiles to aid clinicians in the selection of individualized pharmacotherapy for patients with type 2 diabetes.

METHODS

Relevant articles for a systematic review were identified through PubMed. Randomized, head-to-head comparison studies among incretin therapies were identified and included in the review. Additionally, randomized, controlled monotherapy and combination therapy studies examining glycaemic and extraglycaemic effects of individual incretin therapies from 2007 to 2011 were reviewed.

RESULTS AND DISCUSSION

Glucagon-like peptide-1 receptor agonists are generally preferred over DPP-4 inhibitors because of their greater effectiveness in reducing HbA(1C) , FPG and PPG excursions, and greater weight loss potentiation. As a monotherapy option, longer-acting GLP-1 RAs, including liraglutide and exenatide once-weekly, may be preferred at higher HbA(1C) because of their more pronounced effects on FPG. At lower/near normal HbA(1C) , a short-acting GLP-1 RA, such as exenatide twice-daily, may be a better choice as its effects are more pronounced with PPG. Ideal patients or patient situations for DPP-4 inhibitors include patients who need minimal reduction in HbA(1C,) elderly patients, patients who are unwilling or unable to take an injectable agent, when GLP-1 RAs are contraindicated or when the patient will not benefit from weight loss. Treatment benefits common to all incretin-based therapies include minimal hypoglycaemia risk, potential preservation of β-cell function and effective targeting of multiple organs underlying type 2 diabetes and of comorbidities commonly associated with type 2 diabetes, such as obesity and hypertension.

WHAT IS NEW AND CONCLUSION

Key differences in mechanisms of action and in glycaemic and extra-glycaemic treatment outcomes exist among incretin therapies, both within the GLP-1 RA class, and between GLP-1 RAs and DPP-4 inhibitors. Clinical judgment acknowledging important differences among incretin therapies and treatment-related patient characteristics will aid in the selection of the appropriate incretin agent for individualized pharmacotherapy.

Insulin therapy in type 2 diabetes mellitus

Health care providers and patients have lots of choice to treat type 2 diabetes, but the blood glucose improvement is limited. The one therapy with unlimited potential (at least theoretically) is insulin. Many studies show that glucose control is achievable with insulin safely in most patients with type 2 diabetes. Effective diabetes management at the primary care or specialty level requires a belief in the importance of insulin therapy in uncontrolled patients with type 2 diabetes. This review details the theories, observed outcomes, and how-tos regarding insulin use in type 2 diabetes.

Reevaluating goals of insulin therapy: perspectives from large clinical trials

Recent large clinical trials have shown that intensive glycemic control can reduce microvascular complications, but appropriate and safe glycemic goals to improve macrovascular outcomes in patients with type 2 diabetes remain poorly defined. This article surveys recent epidemiologic studies and interventional trials, examines the current understanding of the natural history of type 2 diabetes, and proposes new goals and tactics for optimizing insulin therapy.

Dipeptidyl peptidase-4 (DPP-4) inhibitors are favourable to glucagon-like peptide-1 (GLP-1) agonists: no

Incretin-based therapies, which include the GLP-1 receptor agonists and DPP-4 inhibitors, use the antidiabetic properties of potentiating the GLP-1 receptor signalling via the regulation of insulin and glucagon secretion, inhibition of gastric emptying and suppression of appetite. Most physicians will start antidiabetic treatment with metformin, but adding a GLP-1 receptor agonist as the second drug seems to be optimal since more patients will reach an HbA1c below 7% than with a DPP-4 inhibitor or another oral antidiabetic agents and with minimal risk of hypoglycaemia. The GLP-1 receptor agonists are also more effective in weight and systolic blood pressure control than DPP-4 inhibitors. The side effects of the GLP-1 receptor agonists are primarily nausea and vomiting, which is less pronounced with the long acting agonists and often transient. A GLP-1 receptor agonist can be recommended before a DPP-4 inhibitor in obese type 2 diabetic patients, who want to lose weight. Furthermore, the GLP-1 receptor agonists cover the whole spectrum of treatment from time of diagnosis with lifestyle treatment to combination treatment with basal insulin.

Transitioning from inpatient to outpatient therapy in patients with in-hospital hyperglycemia

Transition from inpatient to outpatient care for patients with type 2 diabetes mellitus is an important aspect of patient management for which there is no guidance. Intensive glucose lowering with insulin is generally favored for seriously ill hospitalized patients, but after discharge, patients often resume their prior regimens, which may include an array of oral or injected glucose-lowering agents. Factors that should be considered in this transition include goals of care/life expectancy, glycated hemoglobin at hospital admission, home medications for other illnesses and their potential for interactions with antidiabetes treatment, comorbidities, nutritional status, physical disabilities, ability to carry out self-monitoring of blood glucose, risk for hypoglycemia, contraindications to oral medications, health literacy, and financial and other resources. Traditional oral therapies that may be used after the patient leaves the hospital include sulfonylureas, α-glucosidase inhibitors, thiazolidinediones, and metformin. α-Glucosidase inhibitors are limited by gastrointestinal adverse events, and thiazolidinediones by fluid retention and increased risk for heart failure. Thiazolidinediones also require a long period of administration for onset glucose lowering and are not suitable for transitioning hospitalized patients who have been receiving insulin to outpatient care. Metformin is contraindicated in patients with renal, cardiac, or pulmonary insufficiency. Incretin-based therapies, glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors, have limited use in hospitals, but may be suitable for the transition to outpatient treatment. The most common adverse events with glucagon-like peptide-1 inhibitors involve the gastrointestinal system. More formal studies of treatment regimens for patients with hyperglycemia leaving the hospital are needed to guide care for this group.

Efficacy of sitagliptin on blood glucose fluctuation in Japanese type 2 diabetic patients with basal-supported oral therapy

We retrospectively investigated the effect of adding dipeptidyl peptidase-4 (DPP-4) inhibitor and tapering sulfonylurea on blood glucose fluctuation in Asian patients with type 2 diabetes mellitus under basal-supported oral therapy (BOT). We recruited twenty-two consecutive Japanese patients with type 2 diabetes mellitus who had blood glucose fluctuation under the combination therapy of insulin glargine and glimepiride and had sitagliptin initiated with glimepiride tapared. Their hemoglobin A1c levels and mean blood glucose profiles of seven points in self-monitoring blood glucose (SMBG) were 7.4 ± 0.6% and 8.6 ± 2.0 mmol/L, respectively. Sitagliptin was initiated with the dose of 50 mg per day and titrated up to 100 mg per day when necessary. Glimepiride was withdrawn if possible. Blood glucose fluctuation was evaluated with SMBG by calculating M-value, its range (the difference of maximum and minimum blood glucose levels), and its coefficient of variation (CV). Two months after sitagliptin add-on, M-value was decreased from 19 ± 13 to 13 ± 8 (p = 0.04). Blood glucose range and CV were also improved from 9.6 ± 2.9 mmol/L to 7.9 ± 2.6 mmol/L (p = 0.01), and from 33 ± 8% to 29 ± 8% (p < 0.01), respectively. Hemoglobin A1c levels and mean blood glucose profiles were unchanged (p = 0.93 and 0.47). In conclusion, blood glucose fluctuation was significantly improved two months after adding sitagliptin and tapering glimepiride in type 2 diabetic Japanese patients who were treated by BOT with insulin glargine and glimepiride.

DPP-4 inhibitors in the management of type 2 diabetes: a critical review of head-to-head trials

Dipeptidyl peptidase-4 (DPP-4) inhibitors offer new options for the management of type 2 diabetes. Direct comparisons with active glucose-lowering comparators in drug-naive patients have demonstrated that DPP-4 inhibitors exert slightly less pronounced HbA(1c) reduction than metformin (with the advantage of better gastrointestinal tolerability) and similar glucose-lowering effects as with a thiazolidinedione (TZD; with the advantage of no weight gain). In metformin-treated patients, gliptins were associated with similar HbA(1c) reductions compared with a sulphonylurea (SU; with the advantage of no weight gain, considerably fewer hypoglycaemic episodes and no need for titration) and a TZD (with the advantage of no weight gain and better overall tolerability). DPP-4 inhibitors also exert clinically relevant glucose-lowering effects compared with a placebo in patients treated with SU or TZD (of potential interest when metformin is either not tolerated or contraindicated), and as oral triple therapy with a good tolerability profile when added to a metformin-SU or pioglitazone-SU combination. Several clinical trials also showed a consistent reduction in HbA(1c) when DPP-4 inhibitors were added to basal insulin therapy, with no increased risk of hypoglycaemia. Because of the complex pathophysiology of type 2 diabetes and the complementary actions of glucose-lowering agents, initial combination of a DPP-4 inhibitor with either metformin or a glitazone may be applied in drug-naive patients, resulting in greater efficacy and similar safety compared with either drug as monotherapy. However, DPP-4 inhibitors were less effective than GLP-1 receptor agonists for reducing HbA(1c) and body weight, but offer the advantage of being easier to use (oral instead of injected administration) and lower in cost. Only one head-to-head trial demonstrated the non-inferiority of saxagliptin vs sitagliptin. Clearly, more trials of direct comparisons between different incretin-based therapies are needed. Because of their pharmacokinetic characteristics, pharmacodynamic properties (glucose-dependent glucose-lowering effect) and good overall tolerability profile, DPP-4 inhibitors may have a key role to play in patients with renal impairment and in the elderly. The role of DPP-4 inhibitors in the therapeutic armamentarium of type 2 diabetes is rapidly evolving as their potential strengths and weaknesses become better defined mainly through controlled clinical trials.

Effects of MK-0941, a novel glucokinase activator, on glycemic control in insulin-treated patients with type 2 diabetes

OBJECTIVE

To assess the efficacy and safety of MK-0941, a glucokinase activator (GKA), when added to stable-dose insulin glargine in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

In this double-blind study, 587 patients taking stable-dose insulin glargine (±metformin ≥1,500 mg/day) were randomized (1:1:1:1:1) to MK-0941 10, 20, 30, or 40 mg or matching placebo t.i.d. before meals (a.c.). This study included an initial 14-week, dose-ranging phase followed by a 40-week treatment phase during which patients were to be uptitrated as tolerated to 40 mg (or placebo) t.i.d. a.c. The primary efficacy end point was change from baseline in A1C at Week 14.

RESULTS

At Week 14, A1C and 2-h postmeal glucose (PMG) improved significantly versus placebo with all MK-0941 doses. Maximal placebo-adjusted least squares mean changes from baseline in A1C (baseline A1C 9.0%) and 2-h PMG were -0.8% and -37 mg/dL (-2 mmol/L), respectively. No significant effects on fasting plasma glucose were observed at any dose versus placebo. By 30 weeks, the initial glycemic responses noted at 14 weeks were not sustained. MK-0941 at one or more doses was associated with significant increases in the incidence of hypoglycemia, triglycerides, systolic blood pressure, and proportion of patients meeting criteria for predefined limits of change for increased diastolic blood pressure.

CONCLUSIONS

In patients receiving stable-dose insulin glargine, the GKA MK-0941 led to improvements in glycemic control that were not sustained. MK-0941 was associated with an increased incidence of hypoglycemia and elevations in triglycerides and blood pressure.

The role of incretin therapy at different stages of diabetes

The pathogenetic mechanisms causing type 2 diabetes are complex, and include a significant reduction of the incretin effect. In patients with type 2 diabetes, GLP-1 secretion may be impaired, while GIP secretion seems unaffected. In contrast, the insulinotropic activity of GIP is severely altered, whereas that of GLP-1 is maintained to a great extent. Better understanding of the role of incretin hormones in glucose homeostasis has led to the development of incretin-based therapies that complement and offer important advantages over previously used agents. Incretin-based agents have significant glucose-lowering effects, promote weight loss (or are weight-neutral), inhibit glucagon secretion while maintaining counter-regulatory mechanisms, exhibit cardiovascular benefits, and protect β-cells while possessing a low risk profile. At present, incretin-based therapies are most widely used as add on to metformin to provide sufficient glycemic control after metformin failure. However, they are also recommended as monotherapy early in the disease course, and later in triple combination. These agents may also be a promising therapeutic tool in prediabetic subjects. Therefore, a therapeutic algorithm is needed for their optimal application at different stages of diabetes, as suggested in this article.

Choosing a gliptin

The treatment of type 2 diabetes mellitus (T2DM) has included the use of metformin and sulfonylurea (SU) as first-line anti-diabetic therapies world over since years. This remains, despite the knowledge that the combination results in a progressive decline in [beta]-cell function and by 3 years up to 50% of diabetic patients can require an additional pharmacological agent to maintain the glycosylated hemoglobin (HbA1c) <7.0% (UKPDS). Gliptins represent a novel class of agents that improve beta cell health and suppress glucagon, resulting in improved post-prandial and fasting hyperglycemia. They function by augmenting the incretin system (GLP-1 and GIP) preventing their metabolism by dipeptidyl peptidase-4 (DPP-4). Not only are they efficacious but also safe (weight neutral) and do not cause significant hypoglycemia, making it a unique class of drugs. This review focuses on gliptins (sitagliptin, vildagliptin, saxagliptin, linagliptin, and alogliptin) discussing pharmacokinetics, pharmacodynamics, efficacy, and safety.

Emerging role of insulin with incretin therapies for management of type 2 diabetes

Type 2 diabetes mellitus (T2DM) is a progressive disease warranting intensification of treatment, as beta-cell function declines over time. Current treatment algorithms recommend metformin as the first-line agent, while advocating the addition of either basal-bolus or premixed insulin as the final level of intervention. Incretin therapy, including incretin mimetics or enhancers, are the latest group of drugs available for treatment of T2DM. These agents act through the incretin axis, are currently recommended as add-on agents either as second-or third-line treatment, without concurrent use of insulin. Given the novel role of incretin therapy in terms of reducing postprandial hyperglycemia, and favorable effects on weight with reduced incidence of hypoglycemia, we explore alternative options for incretin therapy in T2DM management. Furthermore, as some evidence alludes to incretins potentially increasing betacell mass and altering disease progression, we propose introducing these agents earlier in the treatment algorithm. In addition, we suggest the concurrent use of incretins with insulin, given the favorable effects especially in relation to weight gain.

Safety, efficacy and tolerability of exenatide in combination with insulin in the Association of British Clinical Diabetologists nationwide exenatide audit*

AIM

To assess the extent, safety, efficacy and tolerability of reported off-licence exenatide use through a nationwide audit.

METHODS

The Association of British Clinical Diabetologists hosted a password-protected, online collection of anonymized data of exenatide use in real clinical practice. Three hundred and fifteen contributors from 126 centres across UK provided data on 6717 patients. HbA1c and weight changes, exenatide discontinuation, adverse events and treatment satisfaction were compared between non-insulin and insulin-treated patients.

RESULTS

Four thousand eight hundred and fifty-seven patients had baseline and follow-up treatment status with mean (±s.d.) baseline HbA1c 9.45 ± 1.69% and BMI 40.0 ± 8.2 kg/m(2) . Of the 4857 patients, 1921 (39.6%) used exenatide with insulin. Comparing patients who continued insulin with exenatide with non-insulin-treated patients, mean (±s.e.) latest HbA1c and weight reduction (median 26 weeks) were 0.51 ± 0.06 versus 0.94 ± 0.04% (p < 0.001) and 5.8 ± 0.2 versus 5.5 ± 0.1 kg (p = 0.278). Insulin-treated patients had higher rates of exenatide discontinuation (31.0 vs. 13.9%, p < 0.001), hypoglycaemia (8.9 vs. 6.1%, p < 0.001), gastrointestinal side effects (28.4 vs. 25.0%, p = 0.008) and treatment dissatisfaction (20.8 vs. 5.7%, p < 0.001). However, 34.2% of the patients continuing insulin still achieved HbA1c reduction ≥1%. There was significant insulin discontinuation, dose reduction and greater sulphonylurea discontinuation among insulin-treated patients.

CONCLUSIONS

Addition of exenatide to obese, insulin-treated patients can improve glycaemia and weight. Adverse events were statistically but probably not clinically significantly higher, but combination treatment was less well tolerated. Overall, exenatide was less effective in lowering HbA1c among insulin-treated patients, although significant number of insulin-treated patients still achieved significant HbA1c, weight and insulin reductions. Further research into identifying obese, insulin-treated patients who will tolerate and benefit from exenatide treatment is urgently needed.

The effect of initial therapy with the fixed-dose combination of sitagliptin and metformin compared with metformin monotherapy in patients with type 2 diabetes mellitus

AIMS

This study was conducted to compare the glycaemic efficacy and safety of initial combination therapy with the fixed-dose combination of sitagliptin and metformin versus metformin monotherapy in drug-naive patients with type 2 diabetes.

METHODS

This double-blind study (18-week Phase A and 26-week Phase B) randomized 1250 drug-naÏve patients with type 2 diabetes [mean baseline haemoglobin A1c (HbA1c) 9.9%] to sitagliptin/metformin 50/500 mg bid or metformin 500 mg bid (uptitrated over 4 weeks to achieve maximum doses of sitagliptin/metformin 50/1000 mg bid or metformin 1000 bid). Results of the primary efficacy endpoint (mean HbA1c reductions from baseline at the end of Phase A) are reported herein.

RESULTS

At week 18, mean change from baseline HbA1c was -2.4% for sitagliptin/metformin FDC and -1.8% for metformin monotherapy (p < 0.001); more patients treated with sitagliptin/metformin FDC had an HbA1c value <7% (p < 0.001) versus metformin monotherapy. Changes in fasting plasma glucose were significantly greater with sitagliptin/metformin FDC (-3.8 mmol/l) versus metformin monotherapy (-3.0 mmol/l; p < 0.001). Homeostasis model assessment of β-cell function (HOMA-β) and fasting proinsulin/insulin ratio were significantly improved with sitagliptin/metformin FDC versus metformin monotherapy. Baseline body weight was reduced by 1.6 kg in each group. Both treatments were generally well tolerated with a low and similar incidence of hypoglycaemia. Abdominal pain (1.1 and 3.9%; p = 0.002) and diarrhoea (12.0 and 16.6%; p = 0.021) occurred significantly less with sitagliptin/metformin FDC versus metformin monotherapy; the incidence of nausea and vomiting was similar in both groups.

CONCLUSION

Compared with metformin monotherapy, initial treatment with sitagliptin/metformin FDC provided superior glycaemic improvement with a similar degree of weight loss and lower incidences of abdominal pain and diarrhoea.

Retrospective analysis on the efficacy, safety and treatment failure group of sitagliptin for mean 10-month duration

BACKGROUND

To investigate the clinical results of sitagliptin (SITA) and the characteristics of the treatment failure group or of low responders to SITA.

METHODS

A retrospective study of type 2 diabetic patients reviewed 99 cases, including 12 treatment failure cases, who stopped SITA because of worsening patients' condition, and 87 cases, who continued treatment over five visits (total 9.9±10.1 months) after receiving the prescription of SITA from December 2008 to June 2009. Subjects were classified as five groups administered SITA as an initial combination with metformin (MET), add-on to metformin or sulfonylurea, and switching from sulfonylurea or thiazolidinedione. The changes in HbA1c level from the first to last visit (ΔHbA1c) in treatment maintenance group were subanalyzed.

RESULTS

The HbA1c level was significantly reduced in four groups, including initial coadministration of SITA with metformin (ΔHbA1c=-1.1%, P<0.001), add-on to MET (ΔHbA1c=-0.6%, P=0.017), add-on to sulfonylurea (ΔHbA1c=-0.5%, P<0.001), and switching from thiazolidinedione (ΔHbA1c=-0.3%, P=0.013). SITA was noninferior to sulfonlyurea (ΔHbA1c=-0.2%, P=0.63). There was no significant adverse effect. The treatment failure group had a longer diabeties duration (P=0.008), higher HbA1c (P=0.001) and fasting plasma glucose (P=0.003) compared to the maintenance group. Subanalysis on the tertiles of ΔHbA1c showed that low-response to SITA (tertile 1) was associated with a longer diabetes duration (P=0.009) and lower HbA1c (P<0.001).

CONCLUSION

SITA was effective and safe for use in Korean type 2 diabetic patients. However, its clinical responses and long-term benefit-harm profile is yet to be established.

Sitagliptin or exenatide once weekly for type 2 diabetes: comparison of the clinical trials

INTRODUCTION

There is a need for new and improved treatments for type 2 diabetes. Glucagon-like peptide 1 (GLP-1) is a gut hormone that stimulates insulin secretion and the levels of GLP-1 can be increased by inhibiting DPP-4. Sitagliptin is one of the DDP-4 inhibitors used to increase the levels of GLP-1. Exenatide is an agonist at the GLP-1 receptors, which is resistant to breakdown and has a longer action than GLP-1.

AREAS COVERED

This review compares the clinical trials of sitagliptin and exenatide once weekly in the treatment of type 2 diabetes. Only peer-reviewed trials listed on PubMed were included.

EXPERT OPINION

Both sitagliptin and exenatide once weekly are capable of reducing HbA1c and plasma glucose levels, but exenatide once weekly is more potent than sitagliptin and this may lead to different roles for these agents in the treatment of type 2 diabetes.

Minimizing the risk of hypoglycemia with vildagliptin: Clinical experience, mechanistic basis, and importance in type 2 diabetes management

Even if the true incidence of hypoglycemia in type 2 diabetes mellitus (T2DM) remains difficult to estimate, with highly variable rates reported in the literature, it is likely more common than previously thought. While most hypoglycemic episodes in T2DM are considered "mild," they still have a substantial clinical impact. Severe hypoglycemia also exists in T2DM, with recent landmark studies prompting much debate about the potential role of severe hypoglycemia in cardiovascular morbidity and mortality, even though there is currently no definitive evidence for causality. The challenge in the treatment of T2DM remains the achievement of optimal glycemic control to lower the risk for long-term complications while avoiding hypoglycemia. Successful treatment strategies should therefore include careful selection of therapies to prevent hypoglycemia, starting early in the disease management process, in order to best preserve counterregulation. The dipeptidyl peptidase-4 inhibitor, vildagliptin, is a good treatment option to minimize the risk of hypoglycemia over time, while maintaining good glucose control. Extensive clinical experience is available for vildagliptin, with data published for all stages of the condition and with the low hypoglycemic potential stemming from a solid mechanistic basis.

Sitagliptin is effective and safe as add-on to insulin in patients with absolute insulin deficiency: a case series

Introduction

It is generally believed that incretin-based therapies are effective in patients possessing certain levels of preserved β-cell function. So far, there are no reports that show the effectiveness of dipeptidyl peptidase-4 inhibitors in patients who absolutely lack the capacity for endogenous insulin secretion.

Case presentation

This report describes the efficacy of sitagliptin in three Japanese patients (a 91-year-old Japanese woman with type 1 diabetes, a 54-year-old Japanese man with type 2 diabetes and a 30-year-old Japanese man with features of both type 1 and type 2 diabetes) who had no detectable post-meal C-peptide levels. Although they were receiving intensive insulin therapy together with some oral hypoglycemic agents, their glycemic control remained poor. Sitagliptin was added to the ongoing therapeutic regimen to provide better glycemic control. Although these patients had mild hypoglycemia, effective reductions of hemoglobin A1c levels were observed without any adverse events in the liver and kidney during the following 24 weeks. Two of the patients were able to reduce their insulin doses, and one of the patients could discontinue one of the oral hypoglycemic agents. There was no weight gain or gastrointestinal complaints among the three patients. Post-meal C-peptide levels remained undetectable after sitagliptin treatment.

Conclusion

This report demonstrates that sitagliptin is effective and safe as an add-on therapy to insulin in reducing blood glucose levels in patients who absolutely lack the capacity for endogenous insulin secretion. The improvement seen in glycemic control could not be due to enhanced endogenous insulin secretion, since post-meal C-peptide levels remained undetectable after sitagliptin treatment, but it could be a result of other factors (for example, suppression of glucagon levels). However, the glucagon-suppressive effect of sitagliptin is known to be rather weak and short-lived. Given this background, a novel hypothesis that the glycemic effects of this drug may be caused by mechanisms that are independent of the glucagon-like peptide 1 axis (extra-pancreatic effect) will be discussed.

Efficacy and safety of insulin detemir once daily in combination with sitagliptin and metformin: the TRANSITION randomized controlled trial

AIM

The aim of this trial was to evaluate the efficacy and safety of the combination of once-daily insulin detemir (IDet) and sitagliptin (SITA) versus SITA ± sulphonylurea (SU), both in combination with metformin (MET) in insulin-naive subjects.

METHODS

In a 26-week, open-label, randomized, parallel-group study in type 2 diabetes, insulin-naive subjects concomitantly treated with MET ± second oral antidiabetic drug (OAD) were randomized 1 : 1 to IDet + SITA + MET or SITA + MET ± SU. All continued with MET treatment, and those treated with SU continued if randomized to SITA + MET ± SU. Efficacy endpoints included glycosylated haemoglobin (HbA1c), fasting plasma glucose (FPG), 9-point self-measured plasma glucose (SMPG), weight, body mass index (BMI). Safety endpoints included adverse events (AEs) and hypoglycaemia.

RESULTS

Significantly higher reductions in HbA1c, FPG and SMPG were achieved with IDet + SITA + MET compared with SITA + MET ± SU. Estimated HbA1c decreased by 1.44% in the IDet + SITA + MET group versus 0.89% in SITA + MET ± SU, p < 0.001. FPG decreased by 3.7 mmol/l (66.3 mg/dl) versus 1.2 mmol/l (22.2 mg/dl), p < 0.001, respectively. Small decreases in weight and BMI were observed in both arms, with no significant differences. AEs were mild or moderate and were more common in the SITA + MET ± SU arm than in the IDet + SITA + MET arm. There was no major hypoglycaemia. Observed rates of hypoglycaemia were very low (1.3/1.7 episodes/patient year) in both arms. The subgroup treated with MET and SUs prior to the trial achieved similar results.

CONCLUSIONS

The combination of once-daily IDet with SITA showed a clinically and significantly better improvement in glycaemic control than SITA in combination with or without SUs. Both regimens were associated with a low rate of hypoglycaemia and slight weight reduction.

The effect of pramlintide acetate on glycemic control and weight in patients with type 2 diabetes mellitus and in obese patients without diabetes: a systematic review and meta-analysis

AIM

the objective of this systematic review and meta-analysis was to assess the effect of pramlintide on glycemic control, weight and incidence of nausea and hypoglycaemia in patients with type 2 diabetes mellitus (T2DM) and in obese patients without diabetes (OBP).

METHODS

eight randomized, clinical trials were identified from multiple databases. Qualitative assessments and quantitative analyses were performed.

RESULTS

in four T2DM studies (N = 930,duration of studies 16-52 weeks,120-150 mcg/dose BID-TID), all patients received insulin therapy. In four obesity studies (N = 686,duration of studies 6-24 weeks,120-360 mcg/dose BID-TID), equivalent volumes of placebo were administered before major meals. Pramlintide significantly reduced haemoglobin A1c (HbA1c) (-0.33% [95% CI -0.51, -0.14], p = 0.004) and weight (-2.57 kg, [95% CI -3.44, -1.70], p < 0.00001) versus the control group. More patients in the control group reported hypoglycaemia of any severity versus the pramlintide group (risk ratio 0.84 [95% CI 0.69, 10.3], p = 0.09). In OBP, pramlintide caused a reduction in weight (-2.27 kg [95% CI -2.88, -1.66], p < 0.00001). When event data from both populations were combined, patients randomized to pramlintide were 1.8 times more likely to report nausea of any severity versus control (p = 0.0005).

CONCLUSIONS

pramlintide was associated with a small reduction in HbA1c, and a modest reduction in weight in patients with T2DM or OBP. There was increased incidence of nausea but not hypoglycaemia at any time during therapy. Studies about the long-term effect of pramlintide on diabetes- and cardiovascular-related complications and cost-effectiveness analyses are needed.

Weight Management in Overweight and Obese Patients with Type 2 Diabetes Mellitus

Obesity is recognised as an important risk factor for type 2 diabetes, inducing insulin resistance and pancreatic beta-cell dysfunction. These obesity-related defects tend to progress following weight gain and can eventually lead to worsening hyperglycaemia over time. Thus, effective weight management is crucial for glycaemic control in overweight and obese patients with type 2 diabetes. Current standard strategies for weight management in these patients include lifestyle interventions and pharmacotherapy. Bariatric surgery has become a promising new option for the treatment of obese patients with type 2 diabetes and in recent years incretin-based therapies have become available, which exhibit favourable effects on body weight. Herein, the efficacy of available weight loss interventions is assessed and the role of newer antidiabetic agents examined, focusing on incretin-based therapies.

[Insulin based combination treatments of patients with obesity and type 2 diabetes]

Besides classical antidiabetic goals the contemporary diabetology more intensely focuses on the reduction of cardiovascular risk factors of type 2 diabetic patients. Especially, potentially deleterious consequences of insulin therapies are debated, since avoiding hypoglycemic events and the possibility of weight loss represent advantageous cardiovascular effects of an antidiabetic therapy. On the other hand, a large proportion of patients receive insulin treatment during progression of the disease. In order to improve the cardiovascular risk profile of these patients, the combination of insulin with additional oral antidiabetic treatment should be considered. Positive effects are yielded, if the combination allows an optimized glucose control without an increase of hypoglycemic events or weight gain, or if the insulin dose and the body weight can be reduced. Options of such insulin based combination treatments and their potential cardiovascular impact are discussed.

Sitagliptin: a review of its use in the management of type 2 diabetes mellitus

Sitagliptin (Januvia, Glactiv(R), Tesavel(R)) is a dipeptidyl peptidase-4 inhibitor indicated for the treatment of type 2 diabetes mellitus. Oral sitagliptin as monotherapy or combination therapy was generally well tolerated and improved glycaemic control in well designed clinical trials in patients with type 2 diabetes. Glycosylated haemoglobin (HbA(1c)) levels were significantly reduced with sitagliptin monotherapy relative to voglibose monotherapy or placebo, and with sitagliptin as initial combination therapy with metformin or pioglitazone relative to monotherapy with these agents or placebo. Moreover, sitagliptin monotherapy was noninferior to metformin monotherapy in terms of the reduction in HbA(1c) levels. Significant reductions in HbA(1c) levels, relative to background therapy, were also observed with sitagliptin add-on therapy to ongoing treatment with thiazolidinediones, sulfonylureas or insulin with or without metformin, or metformin alone. In terms of the reduction in HbA(1c) levels as add-on treatment to metformin, sitagliptin was noninferior to glipizide and generally did not differ from rosiglitazone, and as add-on treatment to pioglitazone, it did not differ significantly from metformin. Sitagliptin had a low risk of hypoglycaemia (except when used in combination with agents that may be associated with hypoglycaemia, such as sulfonylureas or insulin) and was generally weight-neutral. Although additional comparative data and longer-term studies with glycaemic and clinical outcomes are required to definitively position sitagliptin relative to other antihyperglycaemic agents, current evidence suggests that it is a useful treatment option for patients with type 2 diabetes, with potential advantages including oral administration, a generally weight-neutral effect and a low risk of hypoglycaemia.

Safety and tolerability of sitagliptin in clinical studies: a pooled analysis of data from 10,246 patients with type 2 diabetes

BACKGROUND

In a previous pooled analysis of 12 double-blind clinical studies that included data on 6,139 patients with type 2 diabetes, treatment with sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, was shown to be generally well tolerated compared with treatment with control agents. As clinical development of sitagliptin continues, additional studies have been completed, and more patients have been exposed to sitagliptin. The purpose of the present analysis is to update the safety and tolerability assessment of sitagliptin by pooling data from 19 double-blind clinical studies.

METHODS

The present analysis included data from 10,246 patients with type 2 diabetes who received either sitagliptin 100 mg/day (N = 5,429; sitagliptin group) or a comparator agent (placebo or an active comparator) (N = 4,817; non-exposed group). The 19 studies from which this pooled population was drawn represent the double-blind, randomized studies that included patients treated with the usual clinical dose of sitagliptin (100 mg/day) for between 12 weeks and 2 years and for which results were available as of July 2009. These 19 studies assessed sitagliptin taken as monotherapy, initial combination therapy with metformin or pioglitazone, or as add-on combination therapy with other antihyperglycemic agents (metformin, pioglitazone, a sulfonylurea +/- metformin, insulin +/- metformin, or rosiglitazone + metformin). Patients in the non-exposed group were taking placebo, metformin, pioglitazone, a sulfonylurea +/- metformin, insulin +/- metformin, or rosiglitazone + metformin. The analysis used patient-level data from each study to evaluate between-group differences in the exposure-adjusted incidence rates of adverse events.

RESULTS

Summary measures of overall adverse events were similar in the sitagliptin and non-exposed groups, except for an increased incidence of drug-related adverse events in the non-exposed group. Incidence rates of specific adverse events were also generally similar between the two groups, except for increased incidence rates of hypoglycemia, related to the greater use of a sulfonylurea, and diarrhea, related to the greater use of metformin, in the non-exposed group and constipation in the sitagliptin group. Treatment with sitagliptin was not associated with an increased risk of major adverse cardiovascular events.

CONCLUSIONS

In this updated pooled safety analysis of data from 10,246 patients with type 2 diabetes, sitagliptin 100 mg/day was generally well tolerated in clinical trials of up to 2 years in duration.

Safety and tolerability of sitagliptin in clinical studies: a pooled analysis of data from 10,246 patients with type 2 diabetes

BACKGROUND

In a previous pooled analysis of 12 double-blind clinical studies that included data on 6,139 patients with type 2 diabetes, treatment with sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, was shown to be generally well tolerated compared with treatment with control agents. As clinical development of sitagliptin continues, additional studies have been completed, and more patients have been exposed to sitagliptin. The purpose of the present analysis is to update the safety and tolerability assessment of sitagliptin by pooling data from 19 double-blind clinical studies.

METHODS

The present analysis included data from 10,246 patients with type 2 diabetes who received either sitagliptin 100 mg/day (N = 5,429; sitagliptin group) or a comparator agent (placebo or an active comparator) (N = 4,817; non-exposed group). The 19 studies from which this pooled population was drawn represent the double-blind, randomized studies that included patients treated with the usual clinical dose of sitagliptin (100 mg/day) for between 12 weeks and 2 years and for which results were available as of July 2009. These 19 studies assessed sitagliptin taken as monotherapy, initial combination therapy with metformin or pioglitazone, or as add-on combination therapy with other antihyperglycemic agents (metformin, pioglitazone, a sulfonylurea +/- metformin, insulin +/- metformin, or rosiglitazone + metformin). Patients in the non-exposed group were taking placebo, metformin, pioglitazone, a sulfonylurea +/- metformin, insulin +/- metformin, or rosiglitazone + metformin. The analysis used patient-level data from each study to evaluate between-group differences in the exposure-adjusted incidence rates of adverse events.

RESULTS

Summary measures of overall adverse events were similar in the sitagliptin and non-exposed groups, except for an increased incidence of drug-related adverse events in the non-exposed group. Incidence rates of specific adverse events were also generally similar between the two groups, except for increased incidence rates of hypoglycemia, related to the greater use of a sulfonylurea, and diarrhea, related to the greater use of metformin, in the non-exposed group and constipation in the sitagliptin group. Treatment with sitagliptin was not associated with an increased risk of major adverse cardiovascular events.

CONCLUSIONS

In this updated pooled safety analysis of data from 10,246 patients with type 2 diabetes, sitagliptin 100 mg/day was generally well tolerated in clinical trials of up to 2 years in duration.

Use of DPP-4 inhibitors in type 2 diabetes: focus on sitagliptin

Inhibition of dipeptidyl peptidase-4 (DPP-4) prevents the inactivation of glucagonlike peptide-1 (GLP-1). This increases circulating levels of active GLP-1, stimulates insulin secretion and inhibits glucagon secretion, which results in lowering of glucose levels and improvement of the glycemic control in patients with type 2 diabetes. This review summarizes experiences with DPP-4 inhibition in the treatment of type 2 diabetes, with a focus on sitagliptin. Sitagliptin has in several clinical studies been shown to improve metabolic control in type 2 diabetes, both when used as monotherapy and when used in combination with metformin, sulfonylurea, thiazolidinediones or insulin. The reduction in HbA(1c) is ≈ 0.6% to 1.0% from baseline levels of 7.5% to 8.7% over 6 to 12 months therapy. Sitagliptin has a favorable safety profile, is highly tolerable, and there is a minimal risk of hypoglycemia. Furthermore, sitagliptin is body weight neutral or induces a slight body weight reduction. Sitagliptin may be used in the early stages of type 2 diabetes in combination with metformin or other treatments in subjects with inadequate glycemic control on these treatments alone. Sitagliptin may also be used in monotherapy and, finally, sitagliptin may be used in combination with insulin in more advanced stages of the disease.