Comparison between sitagliptin and nateglinide on postprandial lipid levels: The STANDARD study

Effects of linagliptin monotherapy compared with voglibose on postprandial lipid profiles in Japanese patients with type 2 diabetes: linagliptin study of effects on postprandial blood glucose (L-STEP) sub-study 1

Recently, we reported that linagliptin had equivalent efficacy to voglibose in reducing postprandial blood glucose levels in drug-naïve patients with type 2 diabetes (L-STEP Study). As a sub-study of the L-STEP Study we examined the effect of linagliptin on postprandial lipids profile. Between October 2012 and April 2014, the study enrolled patients with type 2 diabetes mellitus who had inadequate glycemic control. Patients were randomly assigned to either the linagliptin group (5 mg once daily, n = 85) or the voglibose group (0.2 mg/meal thrice daily, n = 71). Meal tolerance tests were performed at baseline (week 0) and endpoint (week 12). The increments in 4-h postprandial triglyceride, remnant lipoprotein cholesterol (RLP-C), and apolipoprotein B48 (ApoB48) from baseline to endpoint in the linagliptin group were lower (p < 0.001, p = 0.025 and p < 0.001). 4-h postprandial ApoB48 at endpoint was lower in the linagliptin group (p = 0.007), and positive correlation was detected between change of ApoB48 and changes in both triglyceride (r = 0.67, p < 0.001) and RLP-C (r = 0.73, p < 0.001) at 4 h. This study revealed that in drug-naïve Japanese patients with relatively mild type 2 diabetes mellitus, linagliptin improves not only postprandial blood glucose level but also levels of lipids such as TG and RLP-C by reducing the ApoB48 level compared with voglibose.

Does evidence support the high expectations placed in precision medicine? A bibliographic review

Background: Precision medicine is the Holy Grail of interventions that are tailored to a patient's individual characteristics. However, conventional clinical trials are designed to find differences in averages, and interpreting these differences depends on untestable assumptions. Although only an ideal, a constant effect of treatment would facilitate individual management. A direct consequence of a constant effect is that the variance of the outcome measure would be the same in the treated and control arms. We reviewed the literature to explore the similarity of these variances as a foundation for examining whether and how often precision medicine is definitively required. Methods: We reviewed parallel clinical trials with numerical primary endpoints published in 2004, 2007, 2010 and 2013. We collected the baseline and final standard deviations of the main outcome measure. We assessed homoscedasticity by comparing the variance of the primary endpoint between arms through the outcome variance ratio (treated to control group). Results: The review provided 208 articles with enough information to conduct the analysis. One out of five studies (n = 40, 19.2%) had statistically different variances between groups, implying a non-constant-effect. The adjusted point estimate of the mean outcome variance ratio (treated to control group) is 0.89 (95% CI 0.81 to 0.97). Conclusions: The mean variance ratio is significantly lower than 1 and the lower variance was found more often in the intervention group than in the control group, suggesting it is more usual for treated patients to be stable. This observed reduction in variance might also imply that there could be a subgroup of less ill patients who derive no benefit from treatment. This would require further study as to whether the treatment effect outweighs the side effects as well as the economic costs. We have shown that there are ways to analyze the apparently unobservable constant effect.

Does evidence support the high expectations placed in precision medicine? A bibliographic review

Background: Precision medicine is the Holy Grail of interventions that are tailored to a patient's individual characteristics. However, conventional clinical trials are designed to find differences in averages, and interpreting these differences depends on untestable assumptions. Although only an ideal, a constant effect of treatment would facilitate individual management. A direct consequence of a constant effect is that the variance of the outcome measure would be the same in the treated and control arms. We reviewed the literature to explore the similarity of these variances as a foundation for examining whether and how often precision medicine is definitively required. Methods: We reviewed parallel clinical trials with numerical primary endpoints published in 2004, 2007, 2010 and 2013. We collected the baseline and final standard deviations of the main outcome measure. We assessed homoscedasticity by comparing the variance of the primary endpoint between arms through the outcome variance ratio (treated to control group). Results: The review provided 208 articles with enough information to conduct the analysis. One out of five studies (n = 40, 19.2%) had statistically different variances between groups, implying a non-constant-effect. The adjusted point estimate of the mean outcome variance ratio (treated to control group) is 0.89 (95% CI 0.81 to 0.97). Conclusions: The mean variance ratio is significantly lower than 1 and the lower variance was found more often in the intervention group than in the control group, suggesting it is more usual for treated patients to be stable. This observed reduction in variance might also imply that there could be a subgroup of less ill patients who derive no benefit from treatment. This would require further study as to whether the treatment effect outweighs the side effects as well as the economic costs. We have shown that there are ways to analyze the apparently unobservable constant effect.

Does evidence support the high expectations placed in precision medicine? A bibliographic review

Background: Precision medicine is the Holy Grail of interventions that are tailored to a patient’s individual characteristics. However, conventional clinical trials are designed to find differences in averages, and interpreting these differences depends on untestable assumptions. Although only an ideal, a constant effect of treatment would facilitate individual management. A direct consequence of a constant effect is that the variance of the outcome measure would be the same in the treated and control arms. We reviewed the literature to explore the similarity of these variances as a foundation for examining whether and how often precision medicine is definitively required.

Methods: We reviewed parallel clinical trials with numerical primary endpoints published in 2004, 2007, 2010 and 2013. We collected the baseline and final standard deviations of the main outcome measure. We assessed homoscedasticity by comparing the variance of the primary endpoint between arms through the outcome variance ratio (treated to control group).

Results: The review provided 208 articles with enough information to conduct the analysis. One out of five studies (n = 40, 19.2%) had statistically different variances between groups, implying a non-constant-effect. The adjusted point estimate of the mean outcome variance ratio (treated to control group) is 0.89 (95% CI 0.81 to 0.97).

Conclusions: The mean variance ratio is significantly lower than 1 and the lower variance was found more often in the intervention group than in the control group, suggesting it is more usual for treated patients to be stable. This observed reduction in variance might also imply that there could be a subgroup of less ill patients who derive no benefit from treatment. This would require further study as to whether the treatment effect outweighs the side effects as well as the economic costs. We have shown that there are ways to analyze the apparently unobservable constant effect.

Does evidence support the high expectations placed in precision medicine? A bibliographic review

Background: Precision medicine is the Holy Grail of interventions that are tailored to a patient's individual characteristics. However, conventional clinical trials are designed to find differences in averages, and interpreting these differences depends on untestable assumptions. Although only an ideal, a constant effect of treatment would facilitate individual management. A direct consequence of a constant effect is that the variance of the outcome measure would be the same in the treated and control arms. We reviewed the literature to explore the similarity of these variances as a foundation for examining whether and how often precision medicine is definitively required. Methods: We reviewed parallel clinical trials with numerical primary endpoints published in 2004, 2007, 2010 and 2013. We collected the baseline and final standard deviations of the main outcome measure. We assessed homoscedasticity by comparing the variance of the primary endpoint between arms through the outcome variance ratio (treated to control group). Results: The review provided 208 articles with enough information to conduct the analysis. One out of five studies (n = 40, 19.2%) had statistically different variances between groups, implying a non-constant-effect. The adjusted point estimate of the mean outcome variance ratio (treated to control group) is 0.89 (95% CI 0.81 to 0.97). Conclusions: The mean variance ratio is significantly lower than 1 and the lower variance was found more often in the intervention group than in the control group, suggesting it is more usual for treated patients to be stable. This observed reduction in variance might also imply that there could be a subgroup of less ill patients who derive no benefit from treatment. This would require further study as to whether the treatment effect outweighs the side effects as well as the economic costs. We have shown that there are ways to analyze the apparently unobservable constant effect.

Improved glucose regulation in type 2 diabetic patients with DPP-4 inhibitors: focus on alpha and beta cell function and lipid metabolism

Inhibition of dipeptidyl peptidase-4 (DPP-4) is an established glucose-lowering strategy for the management of type 2 diabetes mellitus. DPP-4 inhibitors reduce both fasting and postprandial plasma glucose levels, resulting in reduced HbA1c with low risk for hypoglycaemia and weight gain. They act primarily by preventing inactivation of the incretin hormones glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1, thereby prolonging the enhanced endogenous levels of these hormones after meal ingestion. This in turn causes islet and extrapancreatic effects, including increased glucose sensing in islet alpha and beta cells. These effects result in increased insulin secretion and decreased glucagon secretion being more effective in hyperglycaemic states and reduced insulin secretion and increased glucagon secretion being more effective during hypoglycaemia. Other secondary pharmacological actions of DPP-4 inhibitors include mobilisation and burning of fat during meals, decrease in fat extraction from the gut, reduction of fasting lipolysis and liver fat and increase in LDL particle size. These actions contribute to the clinical effects of DPP-4 inhibition, and the reduced demand for insulin could also lead to a durability benefit. This review summarises the current knowledge of the secondary pharmacological actions of DPP-4 inhibitors that lead to improved glucose regulation in patients with type 2 diabetes, focusing on alpha and beta cell function and lipid metabolism.

Risk of pancreatic adverse events associated with the use of glucagon-like peptide-1 receptor agonist and dipeptidyl peptidase-4 inhibitor drugs: A systematic review and meta-analysis of randomized trials

AIM: To systematically assess risk of pancreatic adverse events with glucagon-like peptide-1 (GLP-1) receptor agonist and dipeptidyl peptidase-4 (DPP-4) inhibitor drugs.

METHODS: We searched PubMed, Embase, CINAHL, Cochrane review of clinical trials, pharmaceutical company clinical trials register, United States Food and Drug Administration website, European Medicines Agency website and ClinicalTrials.gov for randomized controlled trials from inception to October 2013. Randomized control trial studies were selected for inclusion if they reported on pancreatic complication events and/or changes in pancreatic enzyme levels (serum amylase and serum lipase) as adverse events or as serious adverse events for patients who were on GLP-1 receptor agonist and DPP-4 inhibitor drugs. Two independent reviewers extracted data directly. We performed Peto odds ratio (OR) fixed effect meta-analysis of pancreatic adverse events a, and assessed heterogeneity with the I² statistic.

RESULTS: Sixty-eight randomized controlled trials were eligible. A total of 60720 patients were included in our analysis of the association of risk of pancreatic complication events with GLP-1 agents. A total of 89 pancreatic related adverse events occurred among the GLP-1 agents compared to 74 events among the controls. There was a statistically significant increased risk of elevation of pancreatic enzymes associated with GLP-1 agents compared with control (Peto OR = 3.15, 95%CI: 1.56-6.39, P = 0.001, I² = 0%). There was no statistically significant difference in the risk of pancreatic adverse event associated with GLP-1 agent compared with controls (Peto OR = 1.00, 95%CI: 0.73-1.37, P = 1.00, I² = 0%). There were a total of 71 pancreatitis events in patients on GLP-1 agents and 56 pancreatitis events occurred in the control patients. There were 36 reports of pancreatic cancer in these studies. Of these cases, 2 used linagliptin, 2 used alogliptin, 1 used vildagliptin, 7 used saxagliptin while 6 used sitagliptin. The remaining 18 cases occurred among controls.

CONCLUSION: Although GLP-1 based agents are associated with pancreatic enzyme elevation, we were unable to confirm a significant risk of pancreatitis or pancreatic cancer.

Differential therapeutic effects of nateglinide and acarbose on fasting and postprandial lipid profiles: a randomized trial

BACKGROUND

Dyslipidemia is commonly seen in patients with type 2 diabetes mellitus (T2DM). The current study sought to compare the effects of nateglinide and acarbose, two antihyperglycemic agents, on both fasting and postprandial lipid profiles in Chinese subjects with T2DM.

SUBJECTS AND METHODS

For this multicenter, open-label, randomized, active-controlled, parallel-group study, 103 antihyperglycemic agent-naive patients with T2DM were recruited from four hospitals in China. In total, 85 subjects (44 in the nateglinide group, 41 in the acarbose group) with a known complete lipid profile underwent the entire clinical trial and were included in the final analysis. Serum was collected in the fasting state and 30 and 120 min after a standardized meal (postprandial states) to measure the baseline lipid profiles; the same testing was performed upon completion of a 2-week course of nateglinide (120 mg three times a day) or acarbose (50 mg three times a day).

RESULTS

Fasting triglyceride (TG) levels were significantly reduced by both nateglinide and acarbose (P<0.001), with acarbose providing a significantly more robust improvement (vs. nateglinide, P=0.005). Additionally, the TG levels at both postprandial times were significantly reduced by acarbose (P<0.001 at 30 min and P=0.002 at 120 min), whereas nateglinide treatment only significantly reduced the 30-min postprandial TG (P=0.029). Neither nateglinide nor acarbose treatment had significant impact on total cholesterol, high-density lipoprotein, low-density lipoprotein, or non-high-density lipoprotein cholesterol.

CONCLUSIONS

Compared with nateglinide, acarbose has superior therapeutic efficacy for reducing fasting and postprandial TG levels in patients with T2DM.

Pharmacology, physiology, and mechanisms of action of dipeptidyl peptidase-4 inhibitors

Dipeptidyl peptidase-4 (DPP4) is a widely expressed enzyme transducing actions through an anchored transmembrane molecule and a soluble circulating protein. Both membrane-associated and soluble DPP4 exert catalytic activity, cleaving proteins containing a position 2 alanine or proline. DPP4-mediated enzymatic cleavage alternatively inactivates peptides or generates new bioactive moieties that may exert competing or novel activities. The widespread use of selective DPP4 inhibitors for the treatment of type 2 diabetes has heightened interest in the molecular mechanisms through which DPP4 inhibitors exert their pleiotropic actions. Here we review the biology of DPP4 with a focus on: 1) identification of pharmacological vs physiological DPP4 substrates; and 2) elucidation of mechanisms of actions of DPP4 in studies employing genetic elimination or chemical reduction of DPP4 activity. We review data identifying the roles of key DPP4 substrates in transducing the glucoregulatory, anti-inflammatory, and cardiometabolic actions of DPP4 inhibitors in both preclinical and clinical studies. Finally, we highlight experimental pitfalls and technical challenges encountered in studies designed to understand the mechanisms of action and downstream targets activated by inhibition of DPP4.