Efficacy and safety of sitagliptin as add-on therapy on glycemic control and blood glucose fluctuation in Japanese type 2 diabetes subjects ongoing with multiple daily insulin injections therapy

Long-term efficacy and safety of early sitagliptin initiation in individuals with type 2 diabetes: an extension of the SPIKE study

Aims/instruction

We previously demonstrated that sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, slowed down the progression of carotid atherosclerosis in type 2 diabetes participants who were treated with insulin and had no history of cardiovascular disease in the Sitagliptin Preventive study of Intima-Media Thickness Evaluation (SPIKE) trial. This was an extension of the SPIKE trial that examined if early sitagliptin initiation improved long-term cardiovascular outcomes.

Materials and methods

In the SPIKE trial, 282 participants were randomized to either sitagliptin or conventional treatment to examine the effects of sitagliptin on carotid atherosclerosis. All participants who completed the SPIKE trial were recruited to this prospective, observational, cohort study and followed for up to 520 weeks. The primary endpoint was the first occurrence of a major cardiovascular event, which included acute myocardial infarction, stroke, or total mortality.

Results

Events of composite primary outcome occurred in only a few participants in each group (15 [12.6%] in the sitagliptin group and eight in the conventional treatment group [6.7%]). The incidence rate of the primary outcome did not differ significantly between two groups. In post hoc Poisson regression analysis, there were no significant between-group differences in the incidence rates of composite recurrence events for the same outcomes as the primary endpoint.

Conclusions

Early initiation of sitagliptin as add-on therapy to insulin was not linked to reduced risk of composite cardiovascular disease. This may be due to low event numbers in both groups and/or relatively lower continuation rates of DPP-4 inhibitors in the sitagliptin group during the follow-up period.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13340-024-00786-7.

Serum vitamin B12 levels and glycemic fluctuation in patients with type 2 diabetes mellitus

PURPOSE

The aim of the study was to explore the correlation between serum vitamin B12 levels and glycemic fluctuation in patients with type 2 diabetes mellitus (T2DM).

METHODS

This study included 202 T2DM patients in whom blood glucose levels were recorded using a continuous glucose monitoring system retrospectively. Glycemic fluctuation was determined using the average daily risk range (ADRR), a diabetes-specific measure of the risk for hyper- and hypoglycemia.

RESULTS

Serum vitamin B12 levels were higher in T2DM patients with wider glycemic fluctuations than in those with minor glycemic fluctuations (p < 0.001). We observed a positive correlation between serum vitamin B12 levels and ADRR in both T2DM patients who received and did not receive metformin therapy (r = 0.388, p < 0.001 and r = 0.280, p = 0.004, respectively). Multiple linear regression analysis showed that serum vitamin B12 levels were independently correlated with ADRR in T2DM patients who received and did not receive metformin therapy (beta = 0.367, p < 0.001 and beta = 0.410, p < 0.001, respectively).

CONCLUSIONS

Serum vitamin B12 levels are correlated with glycemic fluctuation in patients with T2DM and may serve as an underlying useful biomarker of glycemic fluctuation in T2DM patients, treated with or without metformin therapy.

Development and optimization of sitagliptin and dapagliflozin loaded oral self-nanoemulsifying formulation against type 2 diabetes mellitus

Control of hyperglycemia and prevention of glucose reabsorption (glucotoxicity) are important objectives in the management of type 2 diabetes. This study deals with an oral combined dosage form design for two anti-diabetic drugs, sitagliptin and dapagliflozin using self-nanoemulsifying drug delivery systems (SNEDDS). The SNEDDS were developed using naturally obtained bioactive medium-chain/long-chain triglycerides oil, mixed glycerides and nonionic surfactants, and droplet size was measured followed by the test for antioxidant activities. Equilibrium solubility and dynamic dispersion experiments were conducted to achieve the maximum drug loading. The in vitro digestion, in vivo bioavailability, and anti-diabetic effects were studied to compare the representative SNEDDS with marketed product Dapazin^®. The representative SNEDDS containing black seed oil showed excellent self-emulsification performance with transparent appearance. Characterization of the SNEDDS showed nanodroplets of around 50–66.57 nm in size (confirmed by TEM analysis), in addition to the high drug loading capacity without causing any precipitation in the gastro-intestinal tract. The SNEDDS provided higher antioxidant activity compared to the pure drugs. The in vivo pharmacokinetic parameters of SNEDDS showed significant increase in C_max (1.99 ± 0.21 µg mL⁻¹), AUC (17.94 ± 1.25 µg mL⁻¹), and oral absorption (2-fold) of dapagliflozin compared to the commercial product in the rat model. The anti-diabetic studies showed the significant inhibition of glucose level in treated diabetic mice by SNEDDS combined dose compared to the single drug therapy. The combined dose of sitagliptin-dapagliflozin using SNEDDS could be a potential oral pharmaceutical product for the improved treatment of type 2 diabetes mellitus.

Dipeptidyl dipeptidase-4 inhibitor recovered ischemia through an increase in vasculogenic endothelial progenitor cells and regeneration-associated cells in diet-induced obese mice

Metabolic syndrome (MS), overlapping type 2 diabetes, hyperlipidemia, and/or hypertension, owing to high-fat diet, poses risk for cardiovascular disease. A critical feature associated with such risk is the functional impairment of endothelial progenitor cells (EPCs). Dipeptidyl dipeptidase-4 inhibitors (DPP-4 i) not only inhibit degradation of incretins to control blood glucose levels, but also improve EPC bioactivity and induce anti-inflammatory effects in tissues. In the present study, we investigated the effects of such an inhibitor, MK-06266, in an ischemia model of MS using diet-induced obese (DIO) mice. EPC bioactivity was examined in MK-0626-administered DIO mice and a non-treated control group, using an EPC colony-forming assay and bone marrow cKit⁺ Sca-1⁺ lineage-cells, and peripheral blood-mononuclear cells. Our results showed that, in vitro, the effect of MK-0626 treatment on EPC bioactivities and differentiation was superior compared to the control. Furthermore, microvascular density and pericyte-recruited arteriole number increased in MK-0626-administered mice, but not in the control group. Lineage profiling of isolated cells from ischemic tissues revealed that MK-0626 administration has an inhibitory effect on unproductive inflammation. This occurred via a decrease in the influx of total blood cells and pro-inflammatory cells such as neutrophils, total macrophages, M1, total T-cells, cytotoxic T-cells, and B-cells, with a concomitant increase in number of regeneration-associated cells, such as M2/M ratio and T_reg/T-helper. Laser Doppler analysis revealed that at day 14 after ischemic injury, blood perfusion in hindlimb was greater in MK-0626-treated DIO mice, but not in control. In conclusion, the DPP-4 i had a positive effect on EPC differentiation in MS model of DIO mice. Following ischemic injury, DPP-4 i sharply reduced recruitment of pro-inflammatory cells into ischemic tissue and triggered regeneration and reparation, making it a promising therapeutic agent for MS treatment.

Efficacy and safety of sitagliptin in elderly patients with type 2 diabetes mellitus: A focus on hypoglycemia

AIMS/INTRODUCTION

To investigate the efficacy and safety of sitagliptin in elderly patients with type 2 diabetes mellitus, with a focus on hypoglycemia.

MATERIALS AND METHODS

Type 2 diabetes mellitus patients who started sitagliptin therapy and were followed for 52 weeks were enrolled in the Impact of Sitagliptin on Diabetes Mellitus in Japanese Elderly Patients study. The frequency of hypoglycemia and knowledge of hypoglycemia were analyzed using a questionnaire.

RESULTS

In total, 5,130 patients (aged 73.8 ± 6.1 years) were analyzed. A significant reduction in glycated hemoglobin (-0.7 ± 1.1%, P < 0.001) and glycoalbumin levels (-2.2 ± 3.8%, P < 0.001) was observed at week 52. The percentage of patients with hypoglycemia did not increase from the baseline (3.3%) to week 52 (2.8%) of sitagliptin administration. Hypoglycemia incidence was significantly higher for combination therapy with insulin (odds ratio 17.75, P < 0.001) or sulfonylurea (odds ratio 2.22, P < 0.001). The increase in sitagliptin dose for combination therapy with antidiabetic drug(s) increased the percentage of patients with hypoglycemia (5.6% in sitagliptin increased subgroup, 2.4% in sitagliptin maintained subgroup, P < 0.01). The awareness of hypoglycemia symptoms and attitude to carry glucose as a countermeasure to prevent hypoglycemia increased during the study.

CONCLUSIONS

Sitagliptin did not increase the percentage of patients with hypoglycemia among elderly patients with type 2 diabetes mellitus. However, hypoglycemia occurred more frequently in add-on therapy to sulfonylurea or when the sitagliptin dose was increased in combination therapy, showing that sitagliptin should be used with caution.

Long-term effects of sitagliptin in patients with type 2 diabetes mellitus and hypertension: results from the PROLOGUE study

BACKGROUND

The effects of sitagliptin in patients with type 2 diabetes mellitus and hypertension are unclear. Therefore, we evaluated the long-term effects of sitagliptin in those patients.

METHODS

In the PROLOGUE study, 365 patients were diagnosed as type 2 diabetes mellitus and hypertension, and 189 patients in the sitagliptin group, 176 patients in the conventional group. Fasting blood glucose (FBG), HbA1c, systolic pressure (SP), diastolic pressure (DP), serum urea nitrogen (BUN) and serum creatinine (SCR) were measured at the beginning of the study and after 12 and 24 months of treatment.

RESULTS

FBS and HbA1c levels were not significantly decreased after treatment [12 months: OR: -3.1, 95% CI (-11.3, 5.0); OR: 0.1, 95% CI (0.0, 0.3); 24 months: OR: -0.1, 95% CI (-9.1, 8.8); OR: 0.1, 95% CI (0.0, 0.3), respectively]. BP and DP levels were not significantly decreased after treatment (12 months: OR: 0.9, 95% CI (-2.8, 4.6); OR: 0.6, 95% CI (-2.0, 3.2); 24 months: OR: -0.5, 95% CI (-4.2, 3.1); OR: -1.6, 95% CI (-41, 0.9), respectively]. Furthermore, BUN and SCR levels were not significantly decreased after treatment (12 months: OR: 0.0, 95%CI (-1.2, 1.2); OR: 0.0, 95% CI (-0.1, 0.0); 24 months: OR: 0.4, 95% CI (-1.0, 1.8); OR: -80.8, 95% CI (-201.3, 39.8), respectively]. After adjusting for confounding factors, our results did not change.

CONCLUSIONS

In our study, there was no evidence that treatment with sitagliptin can improve FBS, BP, DP, BUN or SCR in patients with type 2 diabetes mellitus and hypertension.

TRIAL REGISTRATION

University Hospital Medical Information Network Clinical Trials Registry UMIN000004490.

The Influence of Sitagliptin on Treatment-Related Quality of Life in Patients with Type 2 Diabetes Mellitus Receiving Insulin Treatment: A Prespecified Sub-Analysis

INTRODUCTION

Treatment-related quality of life (QOL) is an important aspect of diabetes management. Here, we investigated the influence of sitagliptin, a dipeptidyl peptidase-4 inhibitor, on treatment-related QOL in patients with type 2 diabetes mellitus treated with insulin.

METHODS

This was a prespecified sub-analysis of the Sitagliptin Preventive Study of Intima-Media Thickness Evaluation (SPIKE). The study population consisted of 71 subjects in the sitagliptin group, and 62 subjects in the conventional group who were treated with insulin. Patients of the sitagliptin group were started on sitagliptin in addition to ongoing insulin therapy. In the conventional group, either increasing the dose of current insulin therapy or the addition of oral hypoglycemic agents other than dipeptidyl peptidase-4 inhibitors was allowed to achieve glycemic control. Treatment-related QOL was evaluated before and 104 weeks after the initiation of the study using the Diabetes Therapy-Related QOL Questionnaire 7 (DTR-QOL7).

RESULTS

Forty-five out of 71 subjects in the sitagliptin group and 41 out of 62 subjects in the conventional group filled out the QOL questionnaire at week 104. The DTR-QOL7 score at week 104 was significantly increased from baseline in the sitagliptin group, while that in the conventional group was not changed. However, the changes in score did not differ between the two groups. Change in HbA1c was negatively associated with change in score.

CONCLUSIONS

Our data suggest that sitagliptin added to insulin treatment was comparable to other treatments in terms of its impact on treatment-related QOL.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: UMIN000007396.

FUNDING

Mitsubishi Tanabe Pharma Co., Ono Pharmaceutical Co., and Novo Nordisk.

Efficacy and safety of coadministration of sitagliptin with insulin glargine in type 2 diabetes

BACKGROUND

The aim of the randomized present study was to compare the therapeutic efficacy and safety of a combination of sitagliptin, a dipeptidyl peptidase (DPP)-4 inhibitor, plus insulin glargine (GL + sita) with that of premixed insulin aspart 30 (NOV) for type 2 diabetes (T2D) patients controlled with oral hypoglycemic drugs (HbA1c 7 %-9 %).

METHODS

Sixty-five patients were randomized (1:  1) to the GL + sita (n = 33) and NOV (n = 32) groups and were treated with the combination regimen or premixed insulin twice a day for 16 weeks. The primary endpoint was mean change in HbA1c. Secondary endpoints included fasting blood glucose, blood glucose profiles (seven time points), rate of achieving target HbA1c (<7 % or ≤6.5 %), insulin dose, incidence of hypoglycemia, and body weight.

RESULTS

After 16 weeks, there was no significant difference in HbA1c between the two groups, although more patients achieved HbA1c <7.0 % in the GL + sita group. There was a significant difference in body weight changes between the GL + sita and NOV groups (-0.45 vs 1.52 kg, respectively; P < 0.001). Mean plasma glucose and the mean amplitude of glycemic excursion were significantly lower in the GL + sita than NOV group (P < 0.005), as was the incidence of symptomatic hypoglycemia (2.85 % vs. 13.3 %, respectively; P < 0.001).

CONCLUSION

The combination of GL + sita greatly improved HbA1c in T2D patients (HbA1c 7 %-9 %) with an efficacy that was equal to that of premixed insulin. Thus, GL + sita treatment is a viable option for patients who fail to achieve glycemic control using oral hypoglycemic drugs.

Relationship between frequency of hypoglycemic episodes and changes in carotid atherosclerosis in insulin-treated patients with type 2 diabetes mellitus

The effect of hypoglycemia on the progression of atherosclerosis in patients with type 2 diabetes mellitus (T2DM) remains largely unknown. This is a post hoc analysis of a randomized trial to investigate the relationship between hypoglycemic episodes and changes in carotid intima-media thickness (IMT). Among 274 study subjects, 104 patients experienced hypoglycemic episodes. Increases in the mean IMT and left maximum IMT of the common carotid arteries (CCA) were significantly greater in patients with hypoglycemia compared to those without hypoglycemia. Classification of the patients into three groups according to the frequency of hypoglycemic episodes showed that high frequency of hypoglycemic events was associated with increases in mean IMT-CCA, and left max-IMT-CCA and right max-IMT-CCA. In addition, repetitive episodes of hypoglycemia were associated with a reduction in the beneficial effects of sitagliptin on carotid IMT. Our data suggest that frequency of hypoglycemic episodes was associated with changes in carotid atherosclerosis.

Preventive effect of ipragliflozin on nocturnal hypoglycemia in patients with type 2 diabetes treated with basal-bolus insulin therapy: An open-label, single-center, parallel, randomized control study

The efficacy of the administration of sodium-glucose co-transporter 2 inhibitor or the co-administration of sodium-glucose co-transporter 2 inhibitor and dipeptidyl peptidase-4 inhibitor to insulin therapy is not well known. A total of 58 patients with type 2 diabetes, admitted for glycemic control, were randomized to basal-bolus insulin therapy (BBT) alone or BBT plus 50 mg ipragliflozin and/or 20 mg teneligliptin. Insulin doses were adjusted to maintain normal blood glucose levels. Plasma glucose profiles were estimated by continuous glucose monitoring before discharge. Required insulin doses were not significantly different among the treatment groups. The frequency of nocturnal hypoglycemia was significantly lower in the groups treated with ipragliflozin (6.5 ± 10.6%) and ipragliflozin plus teneligliptin (6.9 ± 14.3%) than in the group treated with BBT alone (42 ± 43.6%). The administration of sodium-glucose co-transporter 2 inhibitor with or without dipeptidyl peptidase-4 inhibitor prevented nocturnal hypoglycemia in type 2 diabetes patients with BBT.

The efficacy and safety of DPP4 inhibitors in patients with type 1 diabetes: A systematic review and meta-analysis

AIMS

Dipeptidyl peptidase-4 (DPP4) inhibitors are a novel class of antidiabetic medication in the treatment of type 2 diabetes mellitus. Several studies have indicated that DPP4 inhibitors could be used for type 1diabetes (T1DM). Here, we performed a meta-analysis to assess the efficacy and safety of DPP4 inhibitor therapy in patients with T1DM.

METHODS

We conducted searches on Medline, Cochrane Library, Web of Science, and EMBASE for relevant studies published before November 21, 2015. Mean difference (MD) with 95% confidence interval (CI) was calculated for the mean glycated hemoglobin (HbA1c) changes and insulin dosage from baseline to endpoint. Risk ratio (RR) with 95% CI was calculated for severe hypoglycemia. Data was extracted by two independent reviewers, and the meta-analysis was performed using Review Manager version 5.3.

RESULTS

Six randomized controlled trials with a total of 228 individuals were finally included into the meta-analysis. DPP4 inhibitors reduced daily insulin dosage significantly (MD -2.41U/day, 95% CI [-3.87, -0.94], P=0.001) but did not reduce HbA1c level (MD 0.0% (0mmol/mol), 95% CI [-0.16, 0.15], P=0.97). Furthermore, DPP4 inhibitors did not change the incidence of severe hypoglycemia (RR 0.81, 95% CI [0.34, 1.93], P=0.64).

CONCLUSION

In patients with T1DM, DPP4 inhibitors combined with insulin do not increase or decrease the risk of hypoglycemia and do not decrease HbA1c levels.

Effect of Glycemic Control on Chylomicron Metabolism and Correlation between Postprandial Metabolism of Plasma Glucose and Chylomicron in Patients with Type 2 Diabetes Treated with Basal-bolus Insulin Therapy with or without Vildagliptin

Aim: Glucagon-like peptide-1 can reduce both postprandial plasma glucose (PG) and chylomicron (CM) levels in patients with type 2 diabetes. However, there have been no reports regarding the relationship between the postprandial metabolism of PG and CM.

Methods: Patients with type 2 diabetes who were admitted for glycemic control were randomized to insulin alone (Ins; n = 16) or insulin plus vildagliptin 100 mg (InsV; n = 16) groups. The insulin dose was adjusted to maintain normal blood glucose levels. The daily profiles of serum TG, remnant lipoprotein cholesterol (RemL-C), and apolipoprotein B48 (ApoB48) were estimated by frequent blood collection on admission and before discharge, and the daily glucose fluctuation profile was also estimated using continuous glucose monitoring (CGM) before discharge.

Results: The daily profiles of serum TG and RemL-C indicated a significant decrease before discharge compared with on admission; however, no significant changes in serum ApoB48 levels were observed in either group. At discharge, daily glucose fluctuation profile and the change in the serum ApoB48 level from fasting to the peak of the daily profile was significantly smaller in the InsV group than in the Ins group. The increment of serum ApoB48 level was significantly correlated with the mean amplitude of glycemic excursions calculated using CGM data only in the Ins group (R² = 0.5242, P <0.001).

Conclusions: Short-term glycemic control decreased serum TG and RemL-C levels, but not ApoB48 levels, and the postprandial metabolism of PG and CM might be regulated by the same mechanism except GLP-1 effect.

Sitagliptin Attenuates the Progression of Carotid Intima-Media Thickening in Insulin-Treated Patients With Type 2 Diabetes: The Sitagliptin Preventive Study of Intima-Media Thickness Evaluation (SPIKE): A Randomized Controlled Trial

OBJECTIVE

The effect of additional treatment with oral hypoglycemic agents on the progression of atherosclerosis remains unknown in insulin-treated patients with type 2 diabetes mellitus (T2DM). We assessed the effects of sitagliptin, a dipeptidyl peptidase 4 inhibitor, on carotid intima-media thickness (IMT) in T2DM.

RESEARCH DESIGN AND METHODS

This prospective, randomized, open-label, blinded end point, multicenter, parallel-group, comparative study included 282 insulin-treated patients with T2DM free of a history of apparent cardiovascular diseases who were recruited at 12 clinical units and randomly allocated to either the sitagliptin group (n = 142) or the control group (n = 140). The primary outcomes were changes in mean and maximum IMT of the common carotid artery measured by echography at the end of a 104-week treatment period.

RESULTS

Sitagliptin had a more potent glucose-lowering effect compared with the conventional treatment (-0.5 ± 1.0% vs. -0.2 ± 0.9%; P = 0.004), without increasing hypoglycemic episodes or body weight. Changes in the mean and left maximum IMT, but not right maximum IMT, of the common carotid arteries were significantly greater after sitagliptin treatment compared with conventional treatment (-0.029 [SE 0.013] vs. 0.024 [0.013] mm [P = 0.005]; -0.065 [0.027] vs. 0.022 [0.026] mm [P = 0.021]; -0.007 [0.031] vs. 0.027 [0.031] mm [P = 0.45], respectively). Over 104 weeks, sitagliptin, but not conventional treatment, significantly reduced the mean IMT and left maximum IMT of common carotid arteries relative to the baseline.

CONCLUSIONS

Sitagliptin attenuated the progression of carotid IMT in insulin-treated patients with T2DM free of apparent cardiovascular disease compared with conventional treatment.

A novel data-mining approach leveraging social media to monitor consumer opinion of sitagliptin

A novel data mining method was developed to gauge the experience of the drug Sitagliptin (trade name Januvia) by patients with diabetes mellitus type 2. To this goal, we devised a two-step analysis framework. Initial exploratory analysis using self-organizing maps was performed to determine structures based on user opinions among the forum posts. The results were a compilation of user's clusters and their correlated (positive or negative) opinion of the drug. Subsequent modeling using network analysis methods was used to determine influential users among the forum members. These findings can open new avenues of research into rapid data collection, feedback, and analysis that can enable improved outcomes and solutions for public health and important feedback for the manufacturer.

Factors Predicting Therapeutic Efficacy of Combination Treatment With Sitagliptin and Insulin in Type 2 Diabetic Patients: The ASSIST-K Study

Background

It is unclear whether dipeptidyl peptidase-4 inhibitors decrease hemoglobin A_1c (HbA_1c) in a glucose-dependent manner in patients on insulin therapy who have impaired insulin secretion. This study investigated factors influencing the efficacy of sitagliptin when used concomitantly with insulin to treat type 2 diabetes mellitus (T2DM) in the real-world setting.

Methods

A retrospective study was conducted of 1,004 T2DM patients at 36 Japanese clinics associated with the Diabetes Task Force of the Kanagawa Physicians Association. Eligible patients had been on insulin for at least 6 months, with a baseline HbA_1c of 7.0% (53 mmol/mol) or higher. Baseline characteristics and laboratory data from 495 patients were subjected to multiple regression analysis to identify factors influencing the change of HbA_1c.

Results

Most patients (n = 809) received sitagliptin at a dose of 50 mg. In the 1,004 patients, HbA_1c decreased by 0.74% (6 mmol/mol) and body weight increased by 0.1 kg after 6 months of combination therapy. Multiple regression analysis showed that a higher baseline HbA_1c, older age, and lower body mass index influenced the change of HbA_1c after 6 months. Hypoglycemic symptoms occurred in 7.4%, but none were severe.

Conclusions

These results emphasize the importance of a higher HbA_1c at the commencement of sitagliptin therapy in patients on insulin. Glucose-dependent suppression of glucagon secretion by sitagliptin may be useful in patients with impaired insulin secretion. Sitagliptin can be used concomitantly with insulin irrespective of the insulin regimen, duration of insulin treatment, and concomitant medications.

Saxagliptin is similar in glycaemic variability more effective in metabolic control than acarbose in aged type 2 diabetes inadequately controlled with metformin

This study compared the effects on glycaemic variability and glucose control between saxagliptin and acarbose as add-on therapies for aged T2DM inadequately controlled with metformin alone. The results showed that compared with acarbose-metformin, saxagliptin-metformin was more effective in glucose control with similar glycaemic variability.

Addition of sitagliptin or metformin to insulin monotherapy improves blood glucose control via different effects on insulin and glucagon secretion in hyperglycemic Japanese patients with type 2 diabetes

This study aimed to explore the effects of the dipeptidyl peptidase-4 inhibitor sitagliptin and the biguanide metformin on the secretion of insulin and glucagon, as well as incretin levels, in Japanese subjects with type 2 diabetes mellitus poorly controlled with insulin monotherapy. This was a single-center, randomized, open-label, parallel group study, enrolling 25 subjects. Eleven patients (hemoglobin A1c [HbA1c] 8.40 ± 0.96%) and 10 patients (8.10 ± 0.54%) on insulin monotherapy completed 12-week treatment with sitagliptin (50 mg) and metformin (750 mg), respectively. Before and after treatment, each subject underwent a meal tolerance test. The plasma glucose, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), C-peptide, and glucagon responses to a meal challenge were measured. HbA1c reductions were similar in patients treated with sitagliptin (0.76 ± 0.18%) and metformin (0.77 ± 0.17%). In the sitagliptin group, glucose excursion during a meal tolerance test was reduced and accompanied by elevations in active GLP-1 and active GIP concentrations. C-peptide levels were unaltered despite reduced glucose responses, while glucagon responses were significantly suppressed (-7.93 ± 1.95% of baseline). In the metformin group, glucose excursion and incretin responses were unaltered. C-peptide levels were slightly increased but glucagon responses were unchanged. Our data indicate that sitagliptin and metformin exert different effects on islet hormone secretion in Japanese type 2 diabetic patients on insulin monotherapy. A glucagon suppressing effect of sitagliptin could be one of the factors improving blood glucose control in patients inadequately controlled with insulin therapy.

Four-Point Preprandial Self-Monitoring of Blood Glucose for the Assessment of Glycemic Control and Variability in Patients with Type 2 Diabetes Treated with Insulin and Vildagliptin

The study explored the utility of four-point preprandial glucose self-monitoring to calculate several indices of glycemic control and variability in a study adding the DPP-4 inhibitor vildagliptin to ongoing insulin therapy. This analysis utilized data from a double-blind, randomized, placebo-controlled crossover study in 29 patients with type 2 diabetes treated with vildagliptin or placebo on top of stable insulin dose. During two 4-week treatment periods, self-monitoring of plasma glucose was undertaken at 4 occasions every day. Glucose values were used to assess several indices of glycemic control quality, such as glucose mean, GRADE, M-VALUE, hypoglycemia and hyperglycemia index, and indices of glycemic variability, such as standard deviation, CONGA, J-INDEX, and MAGE. We found that vildagliptin improved the glycemic condition compared to placebo: mean glycemic levels, and both GRADE and M-VALUE, were reduced by vildagliptin (P < 0.01). Indices also showed that vildagliptin reduced glycemia without increasing the risk for hypoglycemia. Almost all indices of glycemic variability showed an improvement of the glycemic condition with vildagliptin (P < 0.02), though more marked differences were shown by the more complex indices. In conclusion, the study shows that four-sample preprandial glucose self-monitoring is sufficient to yield information on the vildagliptin effects on glycemic control and variability.

Patients with type 2 diabetes mellitus failing on oral agents and starting once daily insulin regimen; a small randomized study investigating effects of adding vildagliptin

Background

The addition of a DDP4-inhibitor to existing insulin therapy reduces HbA1c. However, no data exist about the addition of these agents at the beginning of insulin treatment in type 2 diabetes while this could especially be interesting because it is during this period that considerable residual beta cell function is still present. The benefit of such a strategy could be a lower insulin dose required for glycemic control. The hypothesis of our study was that adding a DPP4-inhibitor at the beginning of insulin treatment could lead to less exogenous insulin requirement, a reduction of hyperinsulinemia and side effects (hypoglycemia and weight gain), less glucose variability and improvement of insulin and glucagon dynamics during a mixed meal test.

Results

In this small clinical trial (trial registration NTR2022) 9 patients were randomized to receive vildagliptin and 6 to receive placebo in addition to start of once daily insulin treatment. Unfortunately, due to a difficult inclusion, the preset sample size of 40 patients could not be met. Median units of insulin at the end of the study was 47 U in the placebo group and 34 U in the vildagliptin group. Median glycemic variability (SD) at the end of study was 2.1 in the placebo group and 1.5 in the vildagliptin group. Median weight gain at the end of study was 3 kg in the placebo and 0.5 kg in the vildagliptin group. Occurrence of hypoglycemia was low in both groups. Insulin, C-peptide, glucose and glucagon levels were comparable during mixed meal tests.

Conclusions

This small randomized study did not have sufficient power to detect effects of the addition of vildagliptin to the start of once daily long-acting insulin. However in our opinion adding a DPP4-inhibitor, especially in this group remains a very interesting approach. This study could be used as a guidance for larger studies that are required to investigate the effects of this intervention on insulin requirements, glycemic variability, hypoglycemia and weight gain.

Electronic supplementary material

The online version of this article (doi:10.1186/1756-0500-7-579) contains supplementary material, which is available to authorized users.

Glycaemic variability in diabetes: a tool for assessing the quality of glycaemic control and the risk of complications

The routine approach to evaluating the effectiveness of diabetes treatment based on the level of glycated haemoglobin (HbA. 1c) accounts for the average glucose level but does not consider the scope and frequency of its fluctuations. The development of computational methods to analyse glycaemic oscillations has made it possible to propose the concept of glycaemic variability (GV). The interest in research focused on GV increased dramatically after continuous glucose monitoring (CGM) technology was introduced, which provided the opportunity to study in detail the temporal structure of blood glucose curves. Numerous methods for assessing GV proposed over the past five decades characterize glycaemic fluctuations as functions of concentration and time and estimate the risks of hypoglycaemia and hyperglycaemia. Accumulating evidence indicates that GV may serve as a significant predictor of diabetic complications. Prospective studies demonstrate that certain GV parameters have independent significance for predicting diabetic retinopathy, nephropathy and cardiovascular diseases. There is evidence that GV correlates with the severity of atherosclerotic vascular lesions and cardiovascular outcomes in diabetic patients. The mechanisms underlying the relationship between GV and vascular complications are being intensively studied, and recent data show that the effect of GV on vascular walls may be mediated by oxidative stress, chronic inflammation and endothelial dysfunction. Average blood glucose levels and GV are considered independent predictors of hypoglycaemia. Increased GV is associated with impaired hormonal response to hypoglycaemia and is a long-term predictor of hypoglycaemia unawareness. These data allow us to conclude that computational methods for analysing GV in patients with diabetes may serve as a promising tool for personalized assessment of glycaemic control and the risk of vascular complications and hypoglycaemia. Thus, the reduction of GV can be regarded as one of the therapeutic targets to treat diabetes.

Rationale, design, and baseline characteristics of a clinical trial for prevention of atherosclerosis in patients with insulin-treated type 2 diabetes mellitus using DPP-4 inhibitor: the Sitagliptin Preventive study of Intima-media thickness Evaluation (SPIKE)

BACKGROUND

Sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, is currently used to achieve glycemic targets in patients with type 2 diabetes mellitus (T2DM). The addition of DPP-4 inhibitors to ongoing insulin therapy is expected to reduce insulin dosage, leading to a reduction in the frequency of hypoglycaemia and/or weight gain. Recent studies have demonstrated potential anti-atherosclerotic effects for DPP-4 inhibitors. The aim of the present ongoing study is to assess the effects of sitagliptin on the progression of atherosclerosis in patients with insulin-treated T2DM using carotid intima-media thickness (IMT), an established marker of cardiovascular disease.

METHODS AND DESIGN

The Sitagliptin Preventive study of Intima media thickness Evaluation (SPIKE) is a prospective, randomized, open-label, blinded-endpoint, multicenter, parallel-group, comparative study. Between February 2012 and September 2012, 282 participants who failed to achieve glycemic control despite insulin therapy were recruited at 12 clinics and randomly allocated to the sitagliptin group (n = 142) or the control group (n = 140). Primary outcomes are changes in maximum and mean IMT of the common carotid artery after 24-month treatment period measured by carotid arterial echography. Secondary outcomes include changes in glycemic control, parameters related to beta-cell function and diabetic nephropathy, occurrence of cardiovascular events and adverse events such as hypoglycaemia, and biochemical markers of vascular function.

DISCUSSION

The present study is designed to assess the effects of sitagliptin on the progression of carotid IMT. Results will be available in the near future, and the findings are expected to provide new strategy to prevent atherosclerosis in patients with insulin-treated T2DM.

CLINICAL TRIAL REGISTRATION

UMIN000007396.

Efficacy of adding once- and thrice-daily voglibose in Japanese type 2 diabetic patients treated with alogliptin

We investigated the efficacy of once- and thrice-daily voglibose, an alpha-glucosidase inhibitor, as an add-on therapy to alogliptin, a dipeptidyl peptidase-4 inhibitor, on glycemic control in Japanese type 2 diabetic patients. In this 12-week, parallel-group, randomized, open-label, three-arm trial, 151 participants treated with alogliptin were randomly allocated to the following three arms; one was the group to initiate once-daily voglibose, another was to initiate thrice daily voglibose, and the other was the control group. The primary endpoint was the change of hemoglobin A1c levels at the end of the study, which was revealed to be significantly different among groups (p < 0.001). The once- and thrice-daily voglibose groups had a significantly greater reduction than the control group; the difference was -0.27% and -0.33% in the once- and thrice-daily voglibose group, respectively (both p < 0.001). No significant difference was observed between the two voglibose groups (p = 0.615). On the other hand, the increase of 1,5-anhydroglucitol levels were 3.3 and 5.5 μg/ml greater in the once- and thrice-daily voglibose groups than the control group (both p < 0.001). The thrice-daily voglibose group had a greater increase of 1,5- anhydroglucitol levels compared to the once-daily voglibose group (p = 0.005). In conclusion, once- and thrice-daily voglibose as an add-on to alogliptin significantly improved glycemic control in Japanese type 2 diabetic patients.