Optimisation of the management of patients with coronary heart disease and type 2 diabetes mellitus

Adverse Effects of Glycemia-Lowering Medications in Type 2 Diabetes

PURPOSE OF REVIEW

Treatment of patients with type 2 diabetes mellitus is focused on preventing the occurrence and delaying the development of macro- and micro-vascular complications. Glycemic control can help prevent these complications, but there is concern about the adverse effects of glycemia-lowering medications. A rational approach is to balance the desired low risk of adverse events against the unwanted higher risk of major complications resulting from suboptimal glucose control.

RECENT FINDINGS

Using the above approach, approved glucose-lowering agents have favorable benefit-to-risk profiles for use in most patients with type 2 diabetes. We first briefly review the mechanism of actions and benefits of the different commonly used classes of glycemia-lowering medications and then discuss adverse effects and safety concern associated with their use. Our overall assessment is that if used appropriately, the different classes of glycemia-lowering medications offer beneficial outcomes with relatively modest and, in some instances, preventable adverse events.

Association of the rs10757274 SNP with coronary artery disease in a small group of a Pakistani population

Objective:

The present study aimed to investigate the association between the rs10757274 SNP (present on locus 9p21 in the gene for CDKN2B-AS1) and coronary artery disease (CAD) in a local population of Pakistan.

Methods:

It was a case-control study. An allele-specific PCR-based strategy was used for the identification of genotypes. A total of 350 samples were used for the investigation, out of which 220 samples were CAD patients and 130 samples were normal healthy individuals. Effects of parameters, like family history of CAD, smoking, presence of diabetes, and hypertension, in changing the chances of CAD were studied. Odds ratio was estimated with 95% confidence interval.

Results:

A strong association was observed between CAD and factors, like smoking (OR: 1.666; 95% CI: 1.042-2.664), presence of hypertension (OR: 26.55; 95% CI: 15.95-44.20), diabetes (OR: 3.009; 95% CI: 1.841-4.920), and family history of CAD (OR: 4.9; 95% CI: 2.965-8.099). Results for the association between the genotype on the basis of rs10757274 showed a strong association between the GG genotype and the occurrence of CAD (OR: 9.603; 95% CI: 5.746-16.05).

Conclusion:

The present results suggest the importance of the 9p21 locus in modulating the chances of CAD.

Comparative safety of newer oral antidiabetic drugs

Oral antidiabetic agents were introduced into clinical practice during the 1950s. Biguanides and sulfonylureas are still used extensively today and their safety and tolerability profiles are well defined. Developments and refinements within these classes have included the introduction of second- and third-generation sulfonylureas, the introduction of modified-release preparations, and the emergence of fixed-dose preparations with metformin and with novel drugs. The latter include the thiazolidinediones, agents with a putative genomic mechanism of action that have been under intense scrutiny since the emergence of severe hepatotoxicity with troglitazone. Recent concerns about thiazolidinediones have centred on the issue of oedema and the risk of precipitating heart failure in vulnerable patients. Only prolonged exposure will determine the long-term safety of thiazolidinediones. Rapid-acting non-sulfonylurea secretagogues appear to be effective and perhaps safer than sulfonylureas in some groups of patients with certain comorbidities (e.g., those with renal impairment). alpha-Glucosidase inhibitors have an excellent safety record and acarbose has been shown to retard the progression from impaired glucose tolerance to Type 2 diabetes. However, their use is limited by tolerability issues.

Risk of death or acute myocardial infarction 10 years after coronary artery bypass surgery in relation to type of diabetes

BACKGROUND

The aim of this study was to assess the long-term risk of death or acute myocardial infarction (AMI) in patients with diabetes mellitus (DM) compared with that in patients without DM after coronary artery bypass grafting (CABG).

METHODS

National registers were used to record death or AMI occurring in 6727 patients who had CABG during 1980 to 1995. Diabetes mellitus in 856 patients (13%) was classified as type 1 (6%) or type 2 treated with insulin (29%), oral drugs (46%), or diet (19%).

RESULTS

The risk of death < or = 30 days of the operation was increased in patients with insulin-treated type 2 DM (odds ratio [OR] 4.6, 95% CI 2.5-8.4) and in those on oral antidiabetic drugs (OR 2.0, 95% CI 1.0-3.8), but not in diet-treated diabetic patients, compared with that in patients without diabetes. At 10 years, the relative risk of death or having an AMI was 1.8 (95% CI 1.5-2.2) in insulin-treated patients and 1.4 (95% CI 1.2-1.7) in patients on oral drugs. No increased risk of late death or AMI was observed in diet-treated patients with diabetes compared with patients without diabetes. Survival at 10 years without an AMI was 40% in insulin-treated type 2 diabetic patients, 48% if on oral drugs, and 59% if diet managed, compared with 66% in nondiabetic patients.

CONCLUSION

Type 2 DM requiring insulin treatment or oral antidiabetic drugs is associated with an increased early and long-term risk of death or AMI after CABG, whereas diet-treated patients have a risk similar to that in patients without diabetes.

Pinitol from soybeans reduces postprandial blood glucose in patients with type 2 diabetes mellitus

The effect of 3-O-methyl-D-chiro-inositol (D-pinitol), purified from soybean, on the postprandial blood glucose response in patients with type 2 diabetes mellitus was examined. Fifteen Korean subjects with type 2 diabetes mellitus (seven men, eight women; 60.3 +/- 3.1 years old) ingested cooked white rice containing 50 g of available carbohydrate with or without prior ingestion of soy pinitol. Pinitol was given either as a 1.2 g dose at 0, 60, 120, or 180 minutes prior to rice ingestion, or as a 0.6 g dose at 60 minutes prior to rice ingestion. Capillary blood glucose levels were monitored for 4 hours after rice consumption. The ingestion of 1.2 g of pinitol 60 minutes prior to rice consumption controlled postprandial capillary blood glucose most effectively, significantly diminishing the postprandial increase in plasma glucose levels measured at 90 and 120 minutes after rice consumption (P < .05). The incremental area under the plasma glucose response curve for subjects who consumed both pinitol and rice was significantly lower than that for subjects who consumed only rice (P < .05), but pinitol had no apparent effect on postprandial insulin levels. Therefore, soybean-derived pinitol may be useful in controlling postprandial increases in blood glucose in patients with type 2 diabetes.

Oral antidiabetic agents: current role in type 2 diabetes mellitus

Type 2 diabetes mellitus is a progressive and complex disorder that is difficult to treat effectively in the long term. The majority of patients are overweight or obese at diagnosis and will be unable to achieve or sustain near normoglycaemia without oral antidiabetic agents; a sizeable proportion of patients will eventually require insulin therapy to maintain long-term glycaemic control, either as monotherapy or in conjunction with oral antidiabetic therapy. The frequent need for escalating therapy is held to reflect progressive loss of islet beta-cell function, usually in the presence of obesity-related insulin resistance. Today's clinicians are presented with an extensive range of oral antidiabetic drugs for type 2 diabetes. The main classes are heterogeneous in their modes of action, safety profiles and tolerability. These main classes include agents that stimulate insulin secretion (sulphonylureas and rapid-acting secretagogues), reduce hepatic glucose production (biguanides), delay digestion and absorption of intestinal carbohydrate (alpha-glucosidase inhibitors) or improve insulin action (thiazolidinediones). The UKPDS (United Kingdom Prospective Diabetes Study) demonstrated the benefits of intensified glycaemic control on microvascular complications in newly diagnosed patients with type 2 diabetes. However, the picture was less clearcut with regard to macrovascular disease, with neither sulphonylureas nor insulin significantly reducing cardiovascular events. The impact of oral antidiabetic agents on atherosclerosis--beyond expected effects on glycaemic control--is an increasingly important consideration. In the UKPDS, overweight and obese patients randomised to initial monotherapy with metformin experienced significant reductions in myocardial infarction and diabetes-related deaths. Metformin does not promote weight gain and has beneficial effects on several cardiovascular risk factors. Accordingly, metformin is widely regarded as the drug of choice for most patients with type 2 diabetes. Concern about cardiovascular safety of sulphonylureas has largely dissipated with generally reassuring results from clinical trials, including the UKPDS. Encouragingly, the recent Steno-2 Study showed that intensive target-driven, multifactorial approach to management, based around a sulphonylurea, reduced the risk of both micro- and macrovascular complications in high-risk patients. Theoretical advantages of selectively targeting postprandial hyperglycaemia require confirmation in clinical trials of drugs with preferential effects on this facet of hyperglycaemia are currently in progress. The insulin-sensitising thiazolidinedione class of antidiabetic agents has potentially advantageous effects on multiple components of the metabolic syndrome; the results of clinical trials with cardiovascular endpoints are awaited. The selection of initial monotherapy is based on a clinical and biochemical assessment of the patient, safety considerations being paramount. In some circumstances, for example pregnancy or severe hepatic or renal impairment, insulin may be the treatment of choice when nonpharmacological measures prove inadequate. Insulin is also required for metabolic decompensation, that is, incipient or actual diabetic ketoacidosis, or non-ketotic hyperosmolar hyperglycaemia. Certain comorbidities, for example presentation with myocardial infarction during other acute intercurrent illness, may make insulin the best option. Oral antidiabetic agents should be initiated at a low dose and titrated up according to glycaemic response, as judged by measurement of glycosylated haemoglobin (HbA1c) concentration, supplemented in some patients by self monitoring of capillary blood glucose. The average glucose-lowering effect of the major classes of oral antidiabetic agents is broadly similar (averaging a 1-2% reduction in HbA1c), alpha-glucosidase inhibitors being rather less effective. Tailoring the treatment to the individual patient is an important principle. Doses are gradually titrated up according to response. However, the maximal glucose-lowering action for sulphonylureas is usually attained at appreciably lower doses (approximately 50%) than the manufacturers' recommended daily maximum. Combinations of certain agents, for example a secretagogue plus a biguanide or a thiazolidinedione, are logical and widely used, and combination preparations are now available in some countries. While the benefits of metformin added to a sulphonylurea were initially less favourable in the UKPDS, longer-term data have allayed concern. When considering long-term therapy, issues such as tolerability and convenience are important additional considerations. Neither sulphonylureas nor biguanides are able to appreciably alter the rate of progression of hyperglycaemia in patients with type 2 diabetes. Preliminary data suggesting that thiazolidinediones may provide better long-term glycaemic stability are currently being tested in clinical trials; current evidence, while encouraging, is not conclusive. Delayed progression from glucose intolerance to type 2 diabetes in high-risk individuals with glucose intolerance has been demonstrated with troglitazone, metformin and acarbose. However, intensive lifestyle intervention can be more effective than drug therapy, at least in the setting of interventional clinical trials. No antidiabetic drugs are presently licensed for use in prediabetic individuals.

Benefits of optimising drug treatment in home-dwelling elderly patients with coronary artery disease

Coronary artery disease (CAD) is prevalent in the elderly and often leads to disability. Consequently, strategies for optimising the prevention and treatment of CAD in the elderly are important from both the individual and societal perspectives. Although it is common knowledge that the elderly are heavy consumers of drugs, there is evidence to show that there is under-prescribing of evidence-based medical therapies in the home-dwelling elderly coronary patient and there may be overuse of some non-evidence-based (antioxidants) and purely symptomatic treatments. In particular, aspirin (acetylsalicylic acid), beta-adrenoceptor antagonists, ACE inhibitors and HMG-CoA reductase inhibitors are under-utilised. Although the evidence base is largely drawn from trials including patients younger than 75 years, it is reasonable to assume that the data applies to patients aged over 75 years and that better use of evidence-based medicines would provide benefits to the home-dwelling aged patient. Evidence from the few multifactorial studies available suggest possible benefits including reduction of cardiovascular events, less disability and better quality of life in old age. At the societal level, this would be reflected in fewer hospitalisations and institutionalisations, which means decreased cost of elderly care.

What happened to the valid POEMs? A survey of review articles on the treatment of type 2 diabetes

OBJECTIVE

To evaluate systematically the review literature on type 2 diabetes to assess transmission of the findings of the United Kingdom prospective diabetes study (UKPDS), an important source of recent valid patient oriented evidence that matters (POEMs).

DESIGN

Inception cohort analysis of the recent medical literature.

STUDIES REVIEWED

Thirty five reviews on treatment of type 2 diabetes.

MAIN OUTCOME MEASURES

Presentation of three types of information from UKPDS in review articles: recommendations based on patient oriented outcomes of study; recommendations contradicted by patient oriented outcomes of study; and recommendations based on disease oriented outcomes for which no patient oriented evidence exists.

RESULTS

Only six of the reviews included the POEM that tight blood glucose control had no effect on diabetes related or overall mortality. Just seven mentioned that metformin treatment was associated with decreased mortality. Most (30) of the reviews did not report that diabetic patients with hypertension benefit more from good blood pressure control than good blood glucose control. No review pointed out that treatment of overweight patients with type 2 diabetes with insulin or sulphonylurea drugs had no effect on microvascular or macrovascular outcomes. Thirteen reviews recommended drugs as first line treatment for which we do not have patient oriented outcomes data. The average validity assessment score was 1.3 out of a possible score of 15 (95% confidence interval 0.9 to 1.8).

CONCLUSIONS

Review articles on the treatment of type 2 diabetes have not accurately transmitted the valid POEM results of the UKPDS to clinicians. Clinicians relying on review articles written by experts as a source of valid POEMs may be misled.

Comparison of glycaemic control and cardiovascular risk profile in patients with type 2 diabetes during treatment with either repaglinide or metformin

OBJECTIVE

To compare glycaemic control and cardiovascular risk profile in patients with type 2 diabetes following 12 months' treatment with either repaglinide or metformin.

STUDY DESIGN AND METHODS

This was an open uncontrolled randomised study in n=112 patients with inadequately controlled type 2 diabetes not previously treated with oral hypoglycaemic agents. Patients beginning treatment with either repaglinide or metformin entered an 8-week titration period (to optimise dosage: repaglinide, 2-4 mg/day; metformin, 1500-2500 mg/day) followed by a 12-month treatment period. Glycaemic control and cardiovascular risk factors were determined at baseline and at the end of the treatment period.

RESULTS

Mean (S.D.) final drug doses were 3 (+/-1) mg/day in the repaglinide group and 2000 (+/-500) mg/day in the metformin group. Significant improvements in glycaemic control [glycated haemoglobin, fasting and 2-h postprandial plasma glucose (PPG)] were demonstrated in both treatment groups. The decrease in PPG was significantly greater in the repaglinide group (P<0.05). During the treatment period, fasting plasma insulin (FPI) decreased significantly in both groups, more so with metformin (P<0.05). Two-hour postprandial plasma insulin (PPI) levels decreased only in the metformin group (P<0.05). Significant improvements between baseline and final visit were demonstrated in one or both groups in the following cardiovascular risk factors: total cholesterol, low-density lipoprotein cholesterol (LDL-C), triglycerides, plasminogen activator inhibitor, lipoprotein(a) and homocysteine. No changes were observed in high-density lipoprotein cholesterol (HDL-C), apolipoprotein A-I, apolipoprotein B, fibrinogen, body mass index (BMI) or blood pressure.

CONCLUSIONS

The use of repaglinide or metformin in drug therapy-nai;ve patients with type 2 diabetes over a 12-month period is associated with improvements in both glycaemic control and cardiovascular risk profile. The latter cannot necessarily be attributed to the pharmacotherapy per se, but provides reassurance in the context of initiating oral hypoglycaemic drug therapy with these agents.