Clinical characteristics of the responders to dipeptidyl peptidase-4 inhibitors in Korean subjects with type 2 diabetes

Predictors of Responsiveness to GLP-1 Receptor Agonists in Insulin-Treated Patients with Type 2 Diabetes

Background

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are potent antihyperglycemic agents with beneficial effects on weight, cardiovascular, and renal outcomes. Physicians lack guidance as to which patients with insulin-requiring type 2 diabetes will respond best to GLP-1 RAs with respect to glycemic control, insulin dose reduction, and weight loss. This study evaluated the efficacy of GLP-1 RAs in patients with type 2 diabetes on insulin and patient factors that may predict a beneficial clinical response.

Methods

Adults with type 2 diabetes treated with insulin who had a GLP-1 RA added to their regimen were evaluated retrospectively. Baseline parameters and outcomes at 3, 6, and 12 months were collected.

Results

Among the 81 patients included, there was a mean reduction in hemoglobin A1C of 0.94% (SD, 0.26; p = 0.0007), 0.40% (SD, 0.21; p = 0.0636), and 0.58% (SD, 0.23, p = 0.0154) at 3, 6, and 12 months, respectively, following the addition of a GLP-1 RA. There was also a reduction in body weight noted at each time point. Baseline characteristics including BMI, duration of diabetes, and insulin requirement did not significantly affect A1C reduction when GLP-1 RA was added. At 3 months, patients with a random C-peptide that was normal (≥0.8 ng/ml) were significantly more likely to have discontinued insulin than those with random C-peptide that was low (<0.8 ng/ml) (11 of 23 vs. 0 of 7 patients, p = 0.029).

Conclusions

The addition of a GLP-1 RA reduced HbA1C, weight, and insulin requirements in this cohort of patients with type 2 diabetes on insulin. BMI, baseline insulin dose, and diabetes duration did not predict response. A C-peptide level ≥ 0.8 ng/ml predicted a beneficial response after 3 months of therapy.

Pharmacogenetics of dipeptidyl peptidase 4 inhibitors in a Taiwanese population with type 2 diabetes

Dipeptidyl peptidase-4 (DPP-4) inhibitors are oral anti-hyperglycemic drugs enabling effective glycemic control in type 2 diabetes (T2D). Despite DPP-4 inhibitors' advantages, the patients' therapeutic response varies. In this retrospective cohort study, 171 Taiwanese patients with T2D were classified as sensitive or resistant to treatment based on the mean change in HbA1c levels. Using an assumption-free genome-wide association study, 45 single nucleotide polymorphisms (SNPs) involved in the therapeutic response to DPP-4 inhibitors (P < 1 × 10-4) were identified at or near PRKD1, CNTN3, ASK, and LOC10537792. A SNP located within the fourth intron of PRKD1 (rs57803087) was strongly associated with DPP-4 inhibitor response (P = 3.2 × 10-6). This is the first pharmacogenomics study on DPP-4 inhibitor treatment for diabetes in a Taiwanese population. Our data suggest that genes associated with β-cell function and apoptosis are involved in the therapeutic effect of DPP-4 inhibitors, even in the presence of additional oral anti-diabetic drugs. Our findings provide information on how genetic variants influence drug response and may benefit the development of personalized medicine.

A Practical Review of C-Peptide Testing in Diabetes

C-peptide is a widely used measure of pancreatic beta cell function. It is produced in equimolar amounts to endogenous insulin but is excreted at a more constant rate over a longer time. Methods of estimation include urinary and unstimulated and stimulated serum sampling. Modern assays detect levels of c-peptide which can be used to guide diabetes diagnosis and management. We explore the evidence behind the various tests available. We recommend the glucagon stimulation c-peptide testing owing to its balance of sensitivity and practicality. C-peptide levels are associated with diabetes type and duration of disease. Specifically a c-peptide level of less than 0.2 nmol/l is associated with a diagnosis of type 1 diabetes mellitus (T1DM). C-peptide level may correlate with microvascular and macrovascular complications and future use of insulin therapy, as well as likely response to other individual therapies. We explore the potential uses of c-peptide measurement in clinical practice.

The Glucose-lowering Efficacy of Sitagliptin in Obese Japanese Patients with Type 2 Diabetes

Objective Dipeptidyl peptidase-4 (DPP-4) inhibitors are the most frequently prescribed oral hypoglycemic agents in Japan. Although a relationship between the efficacy of DPP-4 inhibitors and the body mass index (BMI) has been reported, this relationship is controversial. We investigated whether the BMI value affects the glucose-lowering efficacy of sitagliptin in obese Japanese patients with type 2 diabetes. Methods One hundred sixty-two outpatients with inadequate glycemic control were divided into four groups based on their baseline BMI values. They were then treated with sitagliptin (a DPP-4 inhibitor) for 3 months and followed-up for 12 months. Results Sitagliptin significantly reduced the hemoglobin A1c level (HbA1c: -0.71±0.55%) after 3 months, and continued to reduce the HbA1c level until 12 months. There was no significant difference in the efficacy of sitagliptin among the four BMI groups. A multiple linear regression analysis indicated that the factors contributing to the change in the HbA1c level were the baseline level of HbA1c and the homeostasis model assessment of β-cell function (HOMA-β). In terms of the relationship between the baseline BMI value and the efficacy of sitagliptin treatment, the number of patients who responded to sitagliptin treatment after 3 months was lowest in the group of patients with the highest BMI values. A multiple logistic regression analysis revealed that the baseline HOMA-β function and HbA1c level and a baseline BMI value of ≥30 kg/m² significantly contributed to the response to sitagliptin treatment. Conclusion The results indicated that sitagliptin treatment was effective in controlling glucose metabolism disorder in obese Japanese patients with type 2 diabetes. However, the efficacy of sitagliptin treatment might be attenuated in severely obese patients, such as those with a BMI value of ≥30 kg/m².

C-Peptide Levels Predict the Effectiveness of Dipeptidyl Peptidase-4 Inhibitor Therapy

Background. Our aim was to define the conditions that affect therapeutic success when dipeptidyl peptidase-4 (DPP-4) inhibitor is added to metformin monotherapy. Materials and Methods. We reviewed the medical records of 56 patients who had received DPP-4 inhibitor as an add-on to metformin monotherapy and evaluated their response in the first year of therapy. Fasting blood glucose (FBG), HbA1c, C-peptide, and weight of the patients were recorded at 3-month intervals during the first year of treatment. Results. Patients who added DPP-4 inhibitor to metformin monotherapy had significant weight loss (P = 0.004) and FBG and HbA1c levels were significantly lowered during the first 6 months (both P < 0.001). Baseline levels of C-peptide were predictive for success of the treatment (P = 0.02), even after correction for confounding factors, for example, age, gender, or BMI (P = 0.03). Duration of diabetes was not a predictor of response to treatment (P = 0.60). Conclusion. Our study demonstrates that in patients having inadequate glycemic control, the addition of a DPP-4 inhibitor as a second oral agent to metformin monotherapy provides better glycemic control, protects β-cell reserves, and does not cause weight gain. These effects depend on baseline C-peptide levels.

Adverse effects and safety of SGLT-2 inhibitors

In type 2 diabetes (T2DM), glycaemic control delays the development and slows the progression of complications. Although there are numerous glucose-lowering agents in clinical use, only approximately half of T2DM patients achieve glycaemic control, while undesirable side-effects, such as hypoglycaemia and body weight gain, often impede treatment in those taking these medications. Thus, there is a need for novel agents and treatment options. Sodium-glucose cotransporter-2 inhibitors (SGLT-2-i) have recently been developed for the treatment of T2DM. The available data suggest a good tolerability profile for the three available drugs - canagliflozin, dapagliflozin and empagliflozin - approved by the US Food and Drug Administration (FDA) for the American market as well as in other countries. The most frequently reported adverse events with SGLT-2-i are female genital mycotic infections, urinary tract infections and increased urination. The pharmacodynamic response to SGLT-2-i declines with increasing severity of renal impairment, requiring dosage adjustments or restrictions with moderate-to-severe renal dysfunction. Most patients treated with SGLT-2-i also have a modest reduction in blood pressure and modest effects on serum lipid profiles, some of which are beneficial (increased high-density lipoprotein cholesterol and decreased triglycerides) and others which are not (increased low-density lipoprotein cholesterol, LDL-C). A number of large-scale and longer-term cardiovascular trials are now ongoing. In patients treated with dapagliflozin, a non-significant excess number of breast and bladder cancers has been reported; considered as due to a bias, this is nevertheless being followed in the ongoing trials. No other significant safety issues have been reported so far. Although there is some benefit for several cardiovascular risk factors such as HbA1c, high blood pressure, obesity and increases in LDL-C, adequately powered trials are still required to determine the effects of SGLT-2-i on macrovascular outcomes.

Differences in the HbA1c-lowering efficacy of glucagon-like peptide-1 analogues between Asians and non-Asians: a systematic review and meta-analysis

AIMS

To compare the HbA1c-lowering efficacy of glucagon-like peptide-1 (GLP-1) analogues between Asians and non-Asians with type 2 diabetes.

METHODS

We searched randomized controlled trials from MEDLINE, EMBASE, LILACS, CENTRAL and ClinicalTrials.gov. Studies described in English were included if the treatment duration was 12 weeks or more, information about ethnicity and baseline HbA1c values were available and a GLP-1 analogue was compared with a placebo. For the ethnic comparison, we divided the studies into Asian-dominant studies (≥ 50% Asian participants) and non-Asian-dominant studies (<50% Asian participants).

RESULTS

Among the 837 searched studies, 15 trials were included for the meta-analysis. The weighted mean difference of HbA1c with GLP-1 analogues was -1.16% [95% confidence interval (CI) -1.48, -0.85] in the Asian-dominant studies and -0.83% (95% CI -0.97, -0.70) in the non-Asian-dominant studies. The between-group difference was -0.32% (95% CI -0.64, -0.01; p = 0.04). The relative risk (RR) with 95% CIs for achieving the target HbA1c ≤ 7.0% tended to be greater in the Asian-dominant studies [RR 5.7 (3.8, 8.7)] than in the non-Asian-dominant studies [RR 2.8 (2.4, 3.3)]. Body weight changes were similar between the two groups. Hypoglycaemia tended to be more common in Asian-dominant studies (RR 2.8 [2.3, 3.5]) than in non-Asian-dominant studies (RR 1.5 [1.2, 1.8]), but severe hypoglycaemia was very rare in both groups.

CONCLUSION

GLP-1 analogues lower HbA1c more in Asian-dominant studies than in non-Asian-dominant studies. Further studies are warranted to explore the potential mechanisms of the ethnic difference.

Real-world effectiveness of sitagliptin as add-on therapy in patients with type 2 diabetes mellitus

AIMS

To assess the effectiveness of sitagliptin in glycemic control in a clinical practice.

METHODS

This was a retrospective medical chart review study conducted in a single hospital. A total of 3081 patients with diabetes mellitus who were prescribed sitagliptin were selected, including 2729 continuous sitagliptin users (defined as continuous usage ≥ 24 weeks) and 352 subjects who used sitagliptin for < 24 weeks. An additional 12-month observation period was monitored after initiating sitagliptin to extract clinical information at 3, 6, 9, and 12 months through patient medical chart review.

RESULTS

In the 2729 continuous users, a baseline glycated hemoglobin (HbA1c) level of 9.0% was reduced to 8.1%, 8.1%, 8.1%, and 8.2% at 3, 6, 9, and 12 months, respectively, representing a 0.9% HbA1c level reduction at 3, 6, and 9 months and a 0.8% HbA1c level reduction at 12 months. With a goal of HbA1c value of < 7.0%, 9.1% of the patients were under control at baseline; after initiating sitagliptin, 22.7% of the patients achieved the HbA1c level goal at 3 months, 23.6% at 6 months, 20.8% at 9 months, and 20.4% at 12 months. The proportion of patients attaining the goal of HbA1c level < 7.0% at least doubled at different time points after treatment with sitagliptin.

CONCLUSIONS

In this single-hospital retrospective chart analysis, a meaningful clinical improvement in glycemic control before and after sitagliptin treatment commenced, including HbA1c level reduction and the HbA1c goal attainment rate, was observed. The results reflect the actual clinical practice in a large hospital in Taiwan, and supplement data from randomized controlled trials.

The Effect of DPP-4 Inhibitors on Metabolic Parameters in Patients with Type 2 Diabetes

BACKGROUND

We evaluated the effects of two dipeptidyl peptidase-4 (DPP-4) inhibitors, sitagliptin and vildagliptin, on metabolic parameters in patients with type 2 diabetes mellitus.

METHODS

A total of 170 type 2 diabetes patients treated with sitagliptin or vildagliptin for more than 24 weeks were selected. The patients were separated into two groups, sitagliptin (100 mg once daily, n=93) and vildagliptin (50 mg twice daily, n=77). We compared the effect of each DPP-4 inhibitor on metabolic parameters, including the fasting plasma glucose (FPG), postprandial glucose (PPG), glycated hemoglobin (HbA1c), and glycated albumin (GA) levels, and lipid parameters at baseline and after 24 weeks of treatment.

RESULTS

The HbA1c, FPG, and GA levels were similar between the two groups at baseline, but the sitagliptin group displayed a higher PPG level (P=0.03). After 24 weeks of treatment, all of the glucose-related parameters were significantly decreased in both groups (P=0.001). The levels of total cholesterol and triglycerides were only reduced in the vildagliptin group (P=0.001), although the sitagliptin group received a larger quantity of statins than the vildagliptin group (P=0.002).The mean change in the glucose- and lipid-related parameters after 24 weeks of treatment were not significantly different between the two groups (P=not significant). Neither sitagliptin nor vildagliptin treatment was associated with a reduction in the high sensitive C-reactive protein level (P=0.714).

CONCLUSION

Vildagliptin and sitagliptin exert a similar effect on metabolic parameters, but vildagliptin exerts a more potent beneficial effect on lipid parameters.