HbA(1c) targets for type 2 diabetes: how many, …how far!

An update on the clinical pharmacology of the dipeptidyl peptidase 4 inhibitor alogliptin used for the treatment of type 2 diabetes mellitus

Alogliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor that is a class of relatively new oral hypoglycaemic drugs used in patients with type 2 diabetes (T2DM), can be used as monotherapy or in combination with other anti-diabetic agents, including metformin, pioglitazone, sulfonylureas and insulin with a considerable therapeutic effect. Alogliptin exhibits favorable pharmacokinetic and pharmacodynamic profiles in humans. Alogliptin is mainly metabolized by cytochrome P450 (CYP2D6) and CYP3A4. Dose reduction is recommended for patients with moderate or worse renal impairment. Side effects of alogliptin include nasopharyngitis, upper-respiratory tract infections and headache. Hypoglycaemia is seen in about 1.5% of the T2DM patients. Rare but severe adverse reactions such as acute pancreatitis, serious hypersensitivity including anaphylaxis, angioedema and severe cutaneous reactions such as Stevens-Johnson syndrome have been reported from post-marketing monitoring. Pharmacokinetic interactions have not been observed between alogliptin and other drugs including glyburide, metformin, pioglitazone, insulin and warfarin. The present review aimed to update the clinical information on pharmacodynamics, pharmacokinetics, adverse effects and drug interactions, and to discuss the future directions of alogliptin.

Clinical pharmacology of dipeptidyl peptidase 4 inhibitors indicated for the treatment of type 2 diabetes mellitus

Dipeptidyl peptidase-4 (DPP-4) inhibitors are a class of oral antidiabetic drugs that improve glycaemic control without causing weight gain or increasing hypoglycaemic risk in patients with type 2 diabetes mellitus (T2DM). The eight available DPP-4 inhibitors, including alogliptin, anagliptin, gemigliptin, linagliptin, saxagliptin, sitagliptin, teneligliptin, and vildagliptin, are small molecules used orally with identical mechanism of action and similar safety profiles in patients with T2DM. DPP-4 inhibitors may be used as monotherapy or in double or triple combination with other oral glucose-lowering agents such as metformin, thiazolidinediones, or sulfonylureas. Although DPP-4 inhibitors have the same mode of action, they differ by some important pharmacokinetic and pharmacodynamic properties that may be clinically relevant in some patients. The main differences between the eight gliptins include: potency, target selectivity, oral bioavailability, elimination half-life, binding to plasma proteins, metabolic pathways, formation of active metabolite(s), main excretion routes, dosage adjustment for renal and liver insufficiency, and potential drug-drug interactions. The off-target inhibition of selective DPP-4 inhibitors is responsible for multiorgan toxicities such as immune dysfunction, impaired healing, and skin reactions. As a drug class, the DPP-4 inhibitors have become accepted in clinical practice due to their excellent tolerability profile, with a low risk of hypoglycaemia, a neutral effect on body weight, and once-daily dosing. It is unknown if DPP-4 inhibitors can prevent disease progression. More clinical studies are needed to validate the optimal regimens of DPP-4 inhibitors for the management of T2DM when their potential toxicities are closely monitored.

Hemoglobin A1c, comorbid conditions and all-cause mortality in older patients with diabetes: a retrospective 9-year cohort study

AIMS

To examine whether hemoglobin A1c levels and comorbid conditions are related to all-cause mortality in a cohort of patients with type 1 or 2 diabetes receiving continuous care for 9 years. In patients with comorbid congestive heart failure (CHF), we test for 'reverse epidemiology,' or whether greater HbA1c values are associated with lower risk of mortality.

METHODS

The population for this longitudinal cohort study was 8820 Group Health enrollees in the Seattle area with type 1 or 2 diabetes in 1997 and enrolled continuously from 1997 to 2006. Comorbid conditions were hypertension, coronary artery disease, congestive heart failure, depression, and chronic pulmonary disease. Mistimed HbA1c scores were addressed by multiple imputation, and Cox proportional hazards models estimated associations controlling for other risk factors.

RESULTS

About 30% of the enrollees died in 1998-2006. CHF had the strongest association with all-cause mortality. Compared to enrollees with HbA1c ≥ 7.1% (54 mmol/mol) and < 7.5% (58 mmol/mol; 5th decile), enrollees with HbA1c < 6.4% (46 mmol/mol) had a significantly greater risk of death (HR range: 1.28-2.26). HbA1c > 7.5% had HR < 1.0 but were not significant. For enrollees with diabetes and CHF at baseline, HbA1c scores ≥ 8.7% (72 mmol/mol) had a significantly lower risk of death (HR range: 0.64-0.69).

CONCLUSIONS

In our patient population, HbA1c scores<6.4% have significantly higher all-cause mortality. CHF is a major determinant of all-cause mortality. Adults with comorbid CHF and high HbA1c scores have lower all-cause mortality.

Does personalized diabetology overcome clinical uncertainty and therapeutic inertia in type 2 diabetes?

Uncertainties abound in clinical management of type 2 diabetes. Sources of uncertainty specific to type 2 diabetes originate from the panoply of glycemic (HbA1c) targets, the complexity of drug therapy, the ideal sequence of drugs after metformin failure, the possible harms of anti-hyperglycemic drugs, the outcomes of treatment (surrogate versus clinical) and the hierarchy of risk factors to treat in order to prevent the vascular complications. Ironically, multiple treatment guidelines and algorithms periodically released to improve guidance may generate confusion into clinicians. Moreover, treatment algorithms cannot be truly evidence-based because of a lack of studies comparing all available treatment combination options. Personalized therapy essentially identifies patients who could have major benefits from the therapy as compared with other patients. Personalized medicine for type 2 diabetic has the potential to improve the quality health-care practice of diabetes management, but specific research is needed.

Dipeptidyl peptidase-4 inhibitors in type 2 diabetes therapy--focus on alogliptin

Type 2 diabetes mellitus is a complex and progressive disease that is showing an apparently unstoppable increase worldwide. Although there is general agreement on the first-line use of metformin in most patients with type 2 diabetes, the ideal drug sequence after metformin failure is an area of increasing uncertainty. New treatment strategies target pancreatic islet dysfunction, in particular gut-derived incretin hormones. Inhibition of the enzyme dipeptidyl peptidase-4 (DPP-4) slows degradation of endogenous glucagon-like peptide-1 (GLP-1) and thereby enhances and prolongs the action of the endogenous incretin hormones. The five available DPP-4 inhibitors, also known as 'gliptins' (sitagliptin, vildagliptin, saxagliptin, linagliptin, alogliptin), are small molecules used orally with similar overall clinical efficacy and safety profiles in patients with type 2 diabetes. The main differences between the five gliptins on the market include: potency, target selectivity, oral bioavailability, long or short half-life, high or low binding to plasma proteins, metabolism, presence of active or inactive metabolites, excretion routes, dosage adjustment for renal and liver insufficiency, and potential drug-drug interactions. On average, treatment with gliptins is expected to produce a mean glycated hemoglobin (HbA1c) decrease of 0.5%-0.8%, with about 40% of diabetic subjects at target for the HbA1c goal <7%. There are very few studies comparing DPP-4 inhibitors. Alogliptin as monotherapy or added to metformin, pioglitazone, glibenclamide, voglibose, or insulin therapy significantly improves glycemic control compared with placebo in adult or elderly patients with inadequately controlled type 2 diabetes. In the EXAMINE trial, alogliptin is being compared with placebo on cardiovascular outcomes in approximately 5,400 patients with type 2 diabetes. In clinical studies, DPP-4 inhibitors were generally safe and well tolerated. However, there are limited data on their tolerability, due to their relatively recent marketing approval. Alogliptin will be used most when avoidance of hypoglycemic events is paramount, such as in patients with congestive heart failure, renal failure, and liver disease, and in the elderly.