Are sulfonylureas passé?

Rahim AA, Eliana F, Shrestha HK, Chaudhary S, Ngugi N, Mbanya JC, Aye TT, Latt TS, Akanov ZA, Syed AR, Tandon N, Unnikrishnan AG, Madhu SV, Jawa A, Chowdhury S, Bajaj S, Das AK. Consensus Recommendations on Sulfonylurea and Sulfonylurea Combinations in the Management of Type 2 Diabetes Mellitus - International Task Force

For decades, sulfonylureas (SUs) have been important drugs in the antidiabetic therapeutic armamentarium. They have been used as monotherapy as well as combination therapy. Focus on newer drugs and concerns about the risk of severe hypoglycemia and weight gain with some SUs have led to discussion on their safety and utility. It has to be borne in mind that the adverse events associated with SUs should not be ascribed to the whole class, as many modern SUs, such as glimepiride and gliclazide modified release, are associated with better safety profiles. Furthermore, individualization of treatment, using SUs in combination with other drugs, backed with careful monitoring and patient education, ensures maximum benefits with minimal side effects. The current guidelines, developed by experts from Africa, Asia, and the Middle East, promote the safe and smart use of SUs in combination with other glucose-lowering drugs.

Effects of hypoglycemia on myocardial susceptibility to ischemia-reperfusion injury and preconditioning in hearts from rats with and without type 2 diabetes

BACKGROUND

Hypoglycemia is associated with increased mortality rate in patients with diabetes. The underlying mechanisms may involve reduced myocardial tolerance to ischemia and reperfusion (IR) or reduced capacity for ischemic preconditioning (IPC). As IPC is associated with increased myocardial glucose uptake (MGU) during reperfusion, cardioprotection is linked to glucose metabolism possibly by O-linked β-N-acetylglucosamine (O-GlcNAc). We aimed to investigate the impact of hypoglycemia in hearts from animals with diabetes on myocardial IR tolerance, on the efficacy of IPC and whether modulations of MGU and O-GlcNAc levels are involved in the underlying mechanisms.

METHODS

In a Langendorff model using diabetic ZDF (fa/fa) and non-diabetic (fa/+) rats (n = 6-7 in each group) infarct size (IS) was evaluated after 40 min of global ischemia and 120 min reperfusion during hypoglycemia [(glucose) = 3 mmol/l] and normoglycemia [(glucose) = 11 mmol/l]. Myocardial glucose uptake and O-GlcNAc levels were evaluated during reperfusion. IPC was induced by 2 × 5 min of global ischemia prior to index ischemia.

RESULTS

IS increased in hearts from animals with (p < 0.01) and without (p < 0.01) diabetes during hypoglycemia compared to normoglycemia. IPC reduced IS during normoglycemia in both animals with (p < 0.01) and without (p < 0.01) diabetes. During hypoglycemia, however, IPC only reduced IS in hearts from animals with diabetes (p < 0.05). IPC increased MGU during reperfusion and O-GlcNAc levels in animals with diabetes during hypo- (MGU: p < 0.05, O-GlcNAc: p < 0.05) and normoglycemia (MGU: p < 0.01, O-GlcNAc: p < 0.05) and in animals without diabetes only during normoglycemia (MGU: p < 0.05, O-GlcNAc: p < 0.01).

CONCLUSIONS

Hypoglycemia increases myocardial susceptibility to IR injury in hearts from animals with and without diabetes. In contrast to hearts from animals without diabetes, the hearts from animals with diabetes are amenable to cardioprotection during hypoglycemia. In parallel with IPC induced cardioprotection, MGU and O-GlcNAc levels increase suggesting that increased MGU and O-GlcNAc levels are involved in the mechanisms of IPC.

Practical combination therapy based on pathophysiology of type 2 diabetes

Type 2 diabetes is a complex, chronic, and progressive condition that often necessitates the use of multiple medications to achieve glycemic goals. Clinical guidelines generally recommend intensifying pharmacotherapy if glycemic goals are not achieved after 3 months of treatment. However, for many patients with type 2 diabetes, treatment intensification is delayed or does not occur. Initiating combination therapy early in the disease course has the potential to delay disease progression and improve patient outcomes. Guidelines generally provide a list of agents that may be used in combination regimens and emphasize individualization of treatment. The purpose of this review is to discuss the rationale for combination therapy, considering treatment effects on pathophysiologic aspects of type 2 diabetes and individual drug profiles. The combination of newer antidiabetes therapies with complementary mechanisms of action provides the opportunity to target multiple sites of tissue, organ, and cellular dysfunction.

Antihyperglycemic and antidiabetic effects of Ethyl (S)-2-(1-cyclohexylsulfamide carbamoyloxy) propanoate in streptozotocin-induced diabetic Wistar rats

In this study, we examined the antihyperglycemic and antidiabetic effects of a novel synthesized molecule, the Ethyl (S)-2-(1-cyclohexylsulfamide carbamoyloxy) propanoate (ESP1b), in streptozotocin (STZ)-induced diabetic Wistar rats. Experimental diabetes mellitus was produced by a single intraperitoneal injection of STZ (55mg/kg b.w.). Seven day post-injection, animals have received ESP1b orally at the doses of 5, 10 and 20mg/kg b.w. daily for 28 days. This resulted in a clear decline, in a dose dependent manner, of blood glucose levels during the oral glucose tolerance test (OGTT) and the four weeks of treatment period. ESP1b at 20mg/kg b.w. has alleviated body weight loss, improved plasma insulin concentration and at the same time markedly decreased the values of glycosylated hemoglobin, lipoproteins and atherogenic ratios. Additionally, ESP1b notably restored renal as well as hepatic functions tests. Histopathological examinations of pancreatic tissue also confirmed the previous biochemical findings. Considering the obtained results, it may be concluded that ESP1b possess a potent antihyperglycemic activity in STZ-diabetic rats possibly related to an insulin-secretagogue effect, which may be responsible for the moderate decrease in blood glucose concentration observed in normal rats administrated with this tested compound.

Sulfonylureas and risk of falls and fractures: a systematic review

BACKGROUND

Sulfonylureas have been linked to increased risk of hypoglycemia. Hypoglycemia may lead to falls, and falls may lead to fracture. However, studies quantifying the association between sulfonylureas and fractures are sparse and yield inconsistent results.

OBJECTIVE

The purpose of this article was to review the literature regarding sulfonylurea use and falls or fall-related fractures among older adults with type 2 diabetes mellitus and to delineate areas for future research.

DATA SOURCES

We searched MEDLINE (1966-March 2012) and CINAHL (1937-March 2012) for studies of patients with type 2 diabetes mellitus living in the community or nursing homes.

STUDY SELECTION

The search algorithms combined three domains: (1) diabetic patients, (2) sulfonylurea medications, and (3) fractures or falls. We included only publications in English that pertained to human subjects. We found 9 randomized trials and 12 non-experimental studies that met the inclusion criteria.

STUDY APPRAISAL AND SYNTHESIS METHODS

The guidelines provided by the Cochrane handbook or Agency for Healthcare Research and Quality (AHRQ) Methods Guide are too general to distinguish the quality of included non-experimental studies, so we developed several specific domains based on those general guidelines. These domains included study design, study population, follow-up time, comparison group, exposure definition, outcome definition, induction period, confounding adjustment, and attrition or missing data. The data were not amenable to a meta-analysis.

RESULTS

No clinical trials included fracture as a primary endpoint. Most clinical trials excluded older adults. Most studies were not designed to evaluate the risk of sulfonylureas on fractures or falls. Studies did not show an increased risk of falls/fractures with sulfonylurea.

LIMITATIONS

The data available from existing studies suffer from methodological limitations including insufficient events, lack of primary endpoints, exclusion of older adults, and lack of clarity or inappropriate comparison groups.

CONCLUSION

Future studies are needed to appropriately estimate the effect of sulfonylureas on falls or fall-related fractures in older adults who are at increased risk for hypoglycemia, the hypothesized mechanism for fractures related to sulfonylurea therapy.

Identification of a promising drug candidate for the treatment of type 2 diabetes based on a P2Y(1) receptor agonist

The activation by extracellular nucleotides of pancreatic P2Y receptors, particularly, the P2Y(1)R subtype, increases insulin secretion. Therefore, we developed analogues of the P2Y(1)R receptor agonist 2-MeS-ADP, as potential antidiabetic drugs. Analogue 3A was found to be a potent P2Y(1)R agonist (EC(50) = 0.038 μM vs 0.0025 μM for 2-MeS-ADP) showing no activity at P2Y(2/4/6)Rs. Analogue 3A was stable at pH 1.4 (t(1/2) = 7.3 h) and resistant to hydrolysis vs 2-MeS-ADP by alkaline phosphatase (t(1/2) = 6 vs 4.5 h), human e-NPP1 (4% vs 16% hydrolysis after 20 min), and human blood serum (30% vs 50% hydrolysis after 24 h). Intravenous administration of 3A in naive rats decreased blood glucose from 155 mg/dL to normal values, ca. 87 mg/dL, unlike glibenclamide, leading to subnormal values (i.e., 63 mg/dL). Similar observations were made for streptozotocin (STZ)-treated and db(+)/db(-) mouse models. Furthermore, 3A inhibits platelet aggregation in vitro and elongates bleeding time in mice (iv administration of 30 mg of 3A/kg), increasing bleeding time to 16 vs 9 min for Prasugrel. Oral administration of 30 mg/kg 3A to rats increased tail bleeding volume, similar to aspirin. These findings suggest that 3A may be an effective treatment for type 2 diabetes by reducing both blood glucose levels and platelet aggregation.

The management of Type 2 diabetes: a survey of Australian general practitioners

OBJECTIVE

To explore how clinical and demographic variables impact on the management of diabetes mellitus in general practice.

DESIGN

A structured vignette survey was conducted in Australia. This included nine vignettes chosen at random from 128 developed around seven clinical variables. Respondents were asked to recommend a change in treatment and make specific recommendations. A random sample of general practitioners (GPs) were recruited. Two diabetologists involved in the development of national guidelines also participated.

RESULTS

125 (13.8%) GPs participated. Statistical analyses were used to generate outcome measures. GPs recommended a change in treatment for most (81.1%) cases; were less likely to prescribe a statin (68.5% GPs vs. 76.3% diabetologists), less likely to treat hypertension (66.7% vs.89%) and less likely to refer for lifestyle modification (82.3% vs. 96.5%). Significant disagreement occurred around prescribing or changing oral hypoglycaemics. No GP characteristics showed significant impact. The proportion of GPs who agreed with diabetiologists on dose and choice of drugs was 35.7% for statins, 49.6% for antihypertensives and 39.6% for oral hypoglycaemics.

CONCLUSIONS

There were significant differences between diabetologists and GPs on the management of diabetes. The survey suggests significant under-dosing by GPs. These findings warrant further investigation.

Novel combination treatment of type 2 diabetes DPP-4 inhibition + metformin

Inhibition of dipeptidyl peptidase-4 (DPP-4) as a novel therapy for type 2 diabetes is based on prevention of the inactivation process of bioactive peptides, the most important in the context of treatment of diabetes of which is glucagon-like peptide-1 (GLP-1). Most clinical experience with DPP-4 inhibition is based on vildagliptin (GalvusR, Novartis) and sitagliptin (JanuviaR, Merck). These compounds improve glycemic control both in monotherapy and in combination with other oral hyperglycemic agents. Both have also been shown to efficiently improve glycemic control when added to ongoing metformin therapy in patients with inadequate glycemic control. Under that condition, they reduce HbA1C levels by 0.65%-1.1% (baseline HbA1C 7.2-8.7%) in studies up to 52 weeks of duration in combination versus continuous therapy with metformin alone. Sitagliptin has also been examined in initial combination therapy with metformin have; HbA1 was reduced by this combination by 2.1% (baseline HbA1C 8.8%) after 24 weeks of treatment. Both fasting and prandial glucose are reduced by DPP-4 inhibition in combination with metformin in association with improvement of insulin secretion and insulin resistance and increase in concentrations of active GLP-1. The combination of DPP-4 inhibition and metformin has been shown to be highly tolerable with very low risk of hypoglycemia. Hence, DPP-4 inhibition in combination with metformin is an efficient, safe and tolerable combination therapy for type 2 diabetes.

Why insulin sensitizers but not secretagogues should be retained when initiating insulin in type 2 diabetes

The stringent targets set for HbA(1c) levels in type 2 diabetes are currently achieved by fewer than half the patients in the United States. Failure to manage hyperglycaemia in the early stages of disease results in progressive loss of beta-cell function, which ultimately necessitates the initiation of insulin therapy. At this point, choices have to be made on whether to continue oral anti-diabetic drug therapy and, if so, with which agent(s). Historically, sulfonylureas have been the mainstay of oral anti-diabetic drug therapy; however, their long-term efficacy in patients with depleted beta-cell capacity is doubtful, and other classes of oral anti-diabetic drugs, notably the insulin sensitizers, may prove more reliable. These agents (metformin and thiazolidinediones) appear to provide various benefits over and above sustained glycaemic control, which may variably include reduced loss of beta-cell function as well as improvements to cardiovascular risk factors, morbidity, and mortality. Metformin also limits weight gain associated with insulin therapy. This manuscript presents the case that when insulin therapy is initiated it should be tailored to individual needs through combination with one or more insulin sensitizers rather than a secretagogue.

Fixed-dose combination of pioglitazone and glimepiride in the treatment of Type 2 diabetes mellitus

Type 2 diabetes is characterized by impaired insulin sensitivity and disturbances in β-cell function. While glimepiride stimulates β-cell secretion and leads to a reduction of blood glucose levels, pioglitazone activates peroxisome proliferator-activated receptor-γ and improves insulin resistance. Combining these two modes of action has been shown to improve glucose and lipid metabolism, and to improve the overall cardiovascular risk in patients with Type 2 diabetes. The combination of glimepiride and pioglitazone is generally well tolerated and a fixed combination may lead to an improved compliance in patients. The purpose of this review is to evaluate the clinical data that has been published on this combination, appearing to represent a convenient way to obtain therapeutic targets in patients with Type 2 diabetes mellitus.