Impaired fasting glucose and impaired glucose tolerance: implications for care

Short-term metabolic and cardiovascular effects of metformin in markedly obese adolescents with normal glucose tolerance

OBJECTIVE

Although metformin (MET) is an insulin sensitizer currently used as an adjunct to the treatment of some of the complications of childhood obesity besides type 2 diabetes mellitus, few studies have comprehensively examined its metabolic and clinical effects in obese children with normal glucose tolerance (NGT).

METHODS

We therefore conducted a 4-month double-blind clinical trial in 28 obese [mean body mass index (BMI): 40.3 +/- 5.7 kg/m(2)], insulin-resistant [homeostasis model assessment - insulin resistance: 7.6 +/- 2.8 and whole body insulin sensitivity index (WBISI): 1.5 +/- 0.7] adolescents (age 15.0 +/- 1.3 yr) randomized to MET (n = 15, dose 1500 mg daily) or placebo (n = 13).

RESULTS

The treatment with MET was well tolerated. MET treatment was associated with a decreased BMI (p = 0.02) as well as with a reduction in subcutaneous fat (p = 0.03), particularly the deep subcutaneous fat (p = 0.04) as assessed by magnetic resonance imaging. Postintervention, the MET group had a 35% improvement in insulin sensitivity (WBISI) compared with the placebo group (p = 0.008). However, significance was lost with adjustments for differences in baseline insulin sensitivity (p = 0.09). While there was no change in inflammatory cytokines or lipid parameters, cardiovascular function as assessed by heart rate recovery after exercise improved with MET and worsened in placebo (p = 0.03).

CONCLUSION

Short-term use of MET is well tolerated by obese children with NGT and has a beneficial effect on BMI and autonomic control of the heart as well as a trend toward improved insulin sensitivity. Thus, long-term treatment with MET may provide a means to ameliorate the cardio-metabolic consequences of adolescent obesity.

Hemoglobin A1c: past, present and future

Hemoglobin A1c (HbA1c) has been used for decades to monitor the control of glycemia in diabetes. Although HbA1cis currently undergoing a reassessment, and major developments have been underway in recent years, HbA1c is not recommended at present for diabetes screening or diagnosis. The objective of this review is to summarize the recent developments and to review a potential diagnostic role for HbA1c. Implementation of changes in HbA1c results and units of measurements have been suggested for the purpose of test standardization. These include lower reference ranges (by about 1.5-2 points) and measurement units expressed in percentage (%), as mg/dL (mmol/L) or mmol/mol (or a combination of these units). In diabetes screening and diagnosis, the current diagnostic guidelines use measurement of plasma glucose either fasting or after glucose load. These diagnostic methods have shortcomings warranting a potential diagnostic role for HbA1c. While recent developments in HbA1c methodologies are acknowledged, it is not yet known which changes will be implemented, and how soon. Given the recent literature supporting HbA1c diagnostic abilities, and given the shortcomings of the current guidelines, it is possible that a diagnostic role for HbA1c may be considered in future practice guidelines, globally. Very recently, the first of such recommendations has been proposed by an expert panel, as announced by the US Endocrine Society.

Glucose intolerance in pregnancy and future risk of pre-diabetes or diabetes

OBJECTIVE

The purpose of this study was to test the hypothesis that any degree of abnormal glucose homeostasis detected on antepartum screening for gestational diabetes mellitus (GDM) should be associated with an increased risk of postpartum pre-diabetes or diabetes.

RESEARCH DESIGN AND METHODS

In this prospective cohort study, 487 women underwent 1) antepartum GDM screening by a glucose challenge test (GCT) and a diagnostic oral glucose tolerance test (OGTT) and 2) postpartum metabolic characterization by OGTT at 3 months after delivery. Four baseline glucose tolerance groups were defined on the basis of the antepartum GCT/OGTT: 1) GDM (n = 137); 2) gestational impaired glucose tolerance (GIGT) (n = 91); 3) abnormal GCT with normal glucose tolerance on an OGTT (abnormal GCT NGT) (n = 166); and 4) normal GCT with NGT on an OGTT (normal GCT NGT) (n = 93).

RESULTS

The prevalence of postpartum glucose intolerance (pre-diabetes or diabetes) increased across the groups from normal GCT NGT (3.2%) to abnormal GCT NGT (10.2%) to GIGT (16.5%) to GDM (32.8%) (P(trend) < 0.0001). On logistic regression analysis, all three categories of abnormal glucose homeostasis in pregnancy independently predicted postpartum glucose intolerance: abnormal GCT NGT odds ratio (OR) 3.6 (95% CI 1.01-12.9); GIGT OR 5.7 (1.6-21.1); and GDM OR 14.3 (4.2-49.1). Furthermore, both in pregnancy and at 3 months postpartum, insulin sensitivity (IS(OGTT)) and pancreatic beta-cell function (insulinogenic index/homeostasis model assessment of insulin resistance) progressively decreased across the groups from normal GCT NGT to abnormal GCT NGT to GIGT to GDM (all P(trend) < 0.0001).

CONCLUSIONS

Any degree of abnormal glucose homeostasis in pregnancy independently predicts an increased risk of glucose intolerance postpartum.

Approach to the patient with prediabetes

Prediabetes consists of impaired fasting glucose and/or impaired glucose tolerance and is a significant risk factor for the development of type 2 diabetes, microvascular, and macrovascular disease. The values used to define prediabetes are arbitrary, because prediabetes represents an intermediary category along the continuum from normal glucose levels and tolerance to overt hyperglycemia. The progression from prediabetes to type 2 diabetes occurs over many years, strong evidence to support intervention to delay the progression from prediabetes to diabetes. Large, randomized prospective studies with lifestyle intervention and/or various modes of pharmacotherapy have demonstrated successful delay of diabetes. Several issues in the management of prediabetes remain controversial, such as the role of pharmacotherapy and when to escalate treatment. This article will review some of the issues surrounding the identification and treatment of prediabetes, with an interpretation of the available data to help guide management.

Metformin therapy and clinical uses

Metformin is now established as a first-line antidiabetic therapy for the management of type 2 diabetes. Its early use in treatment algorithms is supported by lack of weight gain, low risk of hypoglycaemia and its mode of action to counter insulin resistance. The drug's anti-atherosclerotic and cardioprotective effects have recently been confirmed in prospective and retrospective studies, and appear to reflect a collection of glucose-independent effects on the vascular endothelium, suppressant effects on glycation, oxidative stress and formation of adhesion molecules, stimulation of fibrinolysis and favourable effects on the lipid profile. Although avoidance of troublesome gastrointestinal tolerability issues requires careful dose titration, the risk of serious adverse events is considered low provided that contra-indications (especially with respect to renal function) are observed. As many of its actions go beyond glucose lowering, emerging evidence indicates potential benefits in other insulin-resistant states and possibly tumour suppression.

One-hour plasma glucose concentration and the metabolic syndrome identify subjects at high risk for future type 2 diabetes

OBJECTIVE

To assess the efficacy of 1-h plasma glucose concentration and the metabolic syndrome in predicting future risk of type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 1,611 subjects from the San Antonio Heart Study, who were free of type 2 diabetes at baseline; who had plasma glucose and insulin concentrations measured at time 0, 30, 60, and 120 min during the oral glucose tolerance test (OGTT); and who had their diabetes status determined with an OGTT after 7-8 years of follow-up, were evaluated. Two models, based on glucose tolerance status, 1-h plasma glucose concentration, and presence of the metabolic syndrome, were tested in predicting the risk for type 2 diabetes at 7-8 years of follow-up.

RESULTS

A cutoff point of 155 mg/dl for the 1-h plasma glucose concentration during the OGTT was used to stratify subjects in each glucose tolerance group into low, intermediate, and high risk for future type 2 diabetes. A model based upon 1-h plasma glucose concentration, Adult Treatment Panel (ATP) III criteria for the metabolic syndrome, and fasting plasma glucose, independent of 2-h plasma glucose, performed equally well in stratifying nondiabetic subjects into low, intermediate, and high risk for future type 2 diabetes and identified a group of normal glucose-tolerant subjects who were at very high risk for future type 2 diabetes.

CONCLUSIONS

The plasma glucose concentration at 1 h during the OGTT is a strong predictor of future risk for type 2 diabetes. A plasma glucose cutoff point of 155 mg/dl and the ATP III criteria for the metabolic syndrome can be used to stratify nondiabetic subjects into three risk groups: low, intermediate, and high risk.

Approach to the human immunodeficiency virus-infected patient with lipodystrophy

Subcutaneous atrophy and central fat accumulation are common among HIV-infected patients receiving highly active antiretroviral therapy, and may be accompanied by dyslipidemia and insulin resistance. These fat changes, although commonly referred to together as lipodystrophy, are best considered as separate disorders, with distinct pathogeneses and treatment approaches. These morphological and metabolic abnormalities first appeared after introduction of protease inhibitors more than 10 yr ago, but research has demonstrated that their pathogenesis is multifactorial, with contributions from other antiretroviral medications, patient-related factors, and HIV itself. Switching to a less toxic highly active antiretroviral therapy regimen has shown partial effectiveness for the management of fat atrophy and lipid abnormalities. Lifestyle modification or surgical approaches are the treatment of choice for lipohypertrophy, although novel therapies targeting the GH axis show promise. HIV-related dyslipidemia may be difficult to treat, and can be complicated by drug-drug interactions between some lipid-lowering medications and antiretroviral medications. Treatment of diabetes in HIV-infected patients should generally follow established guidelines, but thiazolidinediones, rather than metformin, may be considered first-line treatment in a patient with lipoatrophy, given their potential to increase sc fat. The contribution of body fat changes and metabolic abnormalities to cardiovascular risk and the changing risk profiles of newer antiretroviral regimens are under intense investigation.

Impaired fasting glucose with or without impaired glucose tolerance: progressive or parallel states of prediabetes?

Our objective was to determine whether defects underlying impaired fasting glucose (IFG) are maintained and additive when combined with impaired glucose tolerance (IGT) (representing a progressive form of prediabetes) or are distinct in IFG/IGT (reflecting a parallel form of prediabetes). Volunteers with IFG (n = 10), IFG/IGT (n = 14), or normal glucose tolerance (NGT; n = 15) were matched for demographics and anthropometry. Insulin secretion was assessed using the glucose step-up protocol and insulin action through the use of a two-stage hyperinsulinemic euglycemic clamp with infusion of [6,6-(2)H(2)]glucose. Modeling of insulin secretory parameters revealed similar basal (Phi(b)) but diminished dynamic (Phi(d)) components in both IFG and IFG/IGT (P = 0.05 vs. NGT for both). Basal glucose rate of appearance (R(a)) was higher in IFG compared with NGT (P < 0.01) and also, surprisingly, with IFG/IGT (P < 0.04). Moreover, glucose R(a) suppressed more during the low-dose insulin clamp in IFG (P < 0.01 vs. NGT, P = 0.08 vs. IFG/IGT). Insulin-stimulated glucose uptake [glucose rate of disappearance (R(d))] was similar in IFG, IFG/IGT, and NGT throughout the clamp. We conclude that nuances of beta-cell dysfunction observed in IFG were also noted in IFG/IGT. A trend for additional insulin secretory defects was observed in IFG/IGT, possibly suggesting progression in beta-cell failure in this group. In contrast, basal glucose R(a) and its suppressability with insulin were higher in IFG, but not IFG/IGT, compared with NGT. Together, these data indicate that IFG/IGT may be a distinct prediabetic syndrome rather than progression from IFG.

[Poisonings by oral antidiabetic drugs in Spain. Analysis and evolution during 13 years (1991-2003)]

INTRODUCTION

The prevalence of diabetes type 2 increases and increased in the next years. The pharmacology treatment of the diabetes type 2 is the oral antidiabetic oral drugs. The objective of our study is to know the existence and evolution of the poisonings by oral antidiabetics in Spain. We have studied the poisonings registered by oral antidiabetics in the National System of information toxicological, centre of national reference for acute poisonings in our country, during period 1991-2003.

RESULTS

The total number of poisonings was of 309 subjects, being more frequent in women 52.9% versus 47.1% in men. The clinical poisonings were classified in asymptomatic 13.9%, low symptoms 49.5% moderate serious 31.3% serious 5.1%. The pharmacologic group with greater number of poisonings was of sulfonilurea 66.5%, within this group the glyburide one. In the last years poisonings with but of a drug appear appearing in the 2002 poisoning by triple therapy (sulfonilurea-metformin and alpha-glucosidase inhibitor). It is important to emphasize the absence of mortality and the modification of prescription increase of cases of metformin and diminution of alpha-glucosidase inhibitor. In our study we emphasized the greater one I number of poisonings in group of suckling babies and children with respect to the adults. Everything shows the importance of the correct prescription and use of the oral antidiabetics.

Effects of continuous positive airway pressure on cardiovascular risk profile in patients with severe obstructive sleep apnea and metabolic syndrome

BACKGROUND

The increased risk of atherosclerotic morbidity and mortality in patients with obstructive sleep apnea (OSA) has been linked to arterial hypertension, insulin resistance, systemic inflammation, and oxidative stress. We aimed to determine the effects of 8 weeks of therapy with continuous positive airway pressure (CPAP) on glucose and lipid profile, systemic inflammation, oxidative stress, and global cardiovascular disease (CVD) risk in patients with severe OSA and metabolic syndrome.

METHODS

In 32 patients, serum cholesterol, triglycerides, high-density lipoprotein cholesterol, fibrinogen, apolipoprotein A-I, apolipoprotein B (ApoB), high-sensitivity C-reactive protein, interleukin-6, tumor necrosis factor (TNF)-alpha, leptin, malondialdehyde (MDA), and erythrocytic glutathione peroxidase (GPx) activity were measured at baseline and after 8 weeks of CPAP. The insulin resistance index (homeostasis model assessment [HOMA-IR]) was based on the homeostasis model assessment method, the CVD risk was calculated using the multivariable risk factor algorithm.

RESULTS

In patients who used CPAP for > or = 4 h/night (n = 16), CPAP therapy reduced systolic BP and diastolic BP (p = 0.001 and p = 0.006, respectively), total cholesterol (p = 0.002), ApoB (p = 0.009), HOMA-IR (p = 0.031), MDA (p = 0.004), and TNF-alpha (p = 0.037), and increased erythrocytic GPx activity (p = 0.015), in association with reductions in the global CVD risk (from 18.8 +/- 9.8 to 13.9 +/- 9.7%, p = 0.001). No significant changes were seen in patients who used CPAP for < 4 h/night. Mask leak was the strongest predictor of compliance with CPAP therapy.

CONCLUSIONS

In patients with severe OSA and metabolic syndrome, good compliance to CPAP may improve insulin sensitivity, reduce systemic inflammation and oxidative stress, and reduce the global CVD risk.

Metabolic phenotype in the brothers of women with polycystic ovary syndrome

OBJECTIVE

Hyperandrogenemia, insulin resistance, and dyslipidemia demonstrate familial aggregation in the female first-degree relatives of women with polycystic ovary syndrome (PCOS), suggesting that these defects are heritable. Hyperandrogenemia also appears to be the male reproductive phenotype. We performed this study to test the hypothesis that brothers of women with PCOS have metabolic defects similar to those of their proband sisters.

RESEARCH DESIGN AND METHODS

This was a prospective case-control study performed at four academic medical centers in the U.S. Fasting blood was obtained from 196 non-Hispanic white brothers of women with PCOS and 169 control men of age, BMI, and ethnicity comparable to those of brothers. A separate analysis was performed by study site to assess potential regional variations in metabolic parameters.

RESULTS

Overall, brothers of women with PCOS had significantly higher total (P = 0.001) and LDL cholesterol (P = 0.01) as well as triglyceride levels (P = 0.01) compared with control men, although there were regional variations in these differences. There were significant positive correlations between brothers and their sisters with PCOS for total (rho = 0.2, P = 0.009) and LDL cholesterol (rho = 0.3, P = 0.001) and triglyceride (rho = 0.2, P = 0.05) levels. Brothers also had significantly higher fasting insulin levels and homeostatic index of insulin resistance (P = 0.02 for both comparisons) compared with control men.

CONCLUSIONS

Brothers of women with PCOS have dyslipidemia as well as evidence for insulin resistance similar to that of their proband sisters with PCOS. These findings are consistent with the hypothesis that some metabolic abnormalities in PCOS are heritable and are not sex specific.

Normal fasting plasma glucose and risk of type 2 diabetes diagnosis

PURPOSE

The study compares the risk of incident diabetes associated with fasting plasma glucose levels in the normal range, controlling for other risk factors.

METHODS

We identified 46,578 members of Kaiser Permanente Northwest who had fasting plasma glucose levels less than 100 mg/dL between January 1, 1997, and December 31, 2000, and who did not previously have diabetes or impaired fasting glucose. After assigning subjects to 1 of 4 categories (<85, 85-89, 90-94, or 95-99 mg/dL), we followed them until they developed diabetes, died, or left the health plan, or until April 30, 2007. We used Cox regression analysis to estimate the risk of incident diabetes, adjusted for age, sex, body mass index, blood pressure, lipids, smoking, cardiovascular disease, and hypertension.

RESULTS

Subjects developed diabetes at a rate of less than 1% per year during a mean follow-up of 81.0 months. Each milligram per deciliter of fasting plasma glucose increased diabetes risk by 6% (hazard ratio [HR] 1.06, 95% confidence interval [CI], 1.05-1.07, P < .0001) after controlling for other risk factors. Compared with those with fasting plasma glucose levels less than 85 mg/dL, subjects with glucose levels of 95 to 99 mg/dL were 2.33 times more likely to develop diabetes (HR 2.33; 95% CI, 1.95-2.79; P < .0001). Subjects in the 90 to 94 mg/dL group were 49% more likely to progress to diabetes (HR 1.49; 95% CI, 1.23-1.79; P <.0001). All other risk factors except sex were significantly associated with a diabetes diagnosis.

CONCLUSIONS

The strong independent association between the level of normal fasting plasma glucose and the incidence of diabetes after controlling for other risk factors suggests that diabetes risk increases as fasting plasma glucose levels increase, even within the currently accepted normal range.

The prevention of type 2 diabetes

Type 2 diabetes mellitus (T2DM) affects more than 7% of adults in the US and leads to substantial personal and economic burden. In prediabetic states insulin secretion and action--potential targets of preventive interventions--are impaired. In trials lifestyle modification (i.e. weight loss and exercise) has proven effective in preventing incident T2DM in high-risk groups, although weight loss has the greatest effect. Various medications (e.g. metformin, thiazolidinediones and acarbose) can also prevent or delay T2DM. Whether diabetes-prevention strategies also ultimately prevent the development of diabetic vascular complications is unknown, but cardiovascular risk factors are favorably affected. Preventive strategies that can be implemented in routine clinical settings have been developed and evaluated. Widespread application has, however, been limited by local financial considerations, even though cost-effectiveness might be achieved at the population level.

The effect of lowering the threshold for diagnosis of impaired fasting glucose

PURPOSE

The aim of this study was to evaluate the effect of lowering the fasting plasma glucose (FPG) criteria for impaired fasting glucose (IFG) on the prevalence of IFG and the risk for the development of diabetes associated with IFG in Koreans.

MATERIALS AND METHODS

A total of 7,211 subjects who had normal glucose tolerance (NGT) or IFG were recruited. Subjects were evaluated at baseline and after two years follow up. Clinical data including total cholesterol, FPG and blood pressure were examined.

RESULTS

Lowering the criteria for IFG from 6.1 mmol/L (110 mg/dL) to 5.6 mmol/L (100 mg/dL) increased the prevalence of IFG from 6.6% (494 subjects) to 24.4% (1829 subjects). After the 2 years follow up period, 91 subjects (1.3%) developed diabetes. Twenty one (0.3%) subjects developed diabetes among 5,382 NGT subjects and 70 (3.8%) subjects developed diabetes among 1,829 IFG (5.6-7.0 mmol/L) subjects. Lowering the IFG threshold from 6.1 mmol/L to 5.6 mmol/L resulted in a 18.4% decrease in specificity and 23.9% increase in sensitivity for predicting diabetes. The baseline FPG for predicting the development of diabetes after 2 years at a point on the receiver operating characteristic curve that was closest to the ideal 100% sensitivity and 100% specificity was 5.7 mmol/L (103 mg/dL).

CONCLUSION

Lowering the FPG criterion of IFG should have benefits in predicting new onset type 2 diabetes mellitus in Koreans. The economic and health benefits of applying the new IFG criteria should be evaluated in future studies.

Type 2 diabetes mellitus: prevention of macrovascular complications

Type 2 diabetes mellitus is a disease that affects a rapidly increasing number of patients. Most patients with Type 2 diabetes will develop vascular complications. This may be microvascular disease, such as nephropathy, retinopathy or polyneuropathy, and also macrovascular disease, such as coronary heart disease, stroke or peripheral artery disease. Optimal control of elevated blood glucose levels will reduce the symptoms of hyperglycemia and help to prevent the development of complications. In addition, treatment of hypertension and lipid disturbances has been shown to reduce the incidence and severity of vascular complications significantly. The current treatment goals focus on adequate and aggressive treatment of these three risk factors. The central dogma for treatment of blood glucose, blood pressure and cholesterol levels is 'the lower the better'. Ongoing trials evaluate the effect of further lowering these treatment goals and of specific types of medication on cardiovascular events.

Does the new American Diabetes Association definition for impaired fasting glucose improve its ability to predict type 2 diabetes mellitus in Spanish persons? The Asturias Study

In 2003, the American Diabetes Association reduced the lower limit defining impaired fasting glucose (IFG) to 100 mg/dL. The aim of this study was to analyze the impact of this change in the definition of IFG in a low-risk white population from northern Spain. The Asturias Study is a prospective, population-based survey of diabetes and cardiovascular risk factors. The baseline examination was carried out between 1998 and 1999 when 1034 individuals (age range, 30-75 years) were randomly selected to determine the prevalence of type 2 diabetes mellitus and prediabetes in the Principality of Asturias (northern Spain). In 2004 to 2005, these same subjects were invited for a follow-up examination. All participants without known diabetes underwent an oral glucose tolerance test both at baseline and follow-up. Application of the new American Diabetes Association definition resulted in 3 times more persons having IFG. The incidence rates of diabetes were 3.8, 19.5, and 58.0 per 1000 person-years in subjects with initial FPG values <100, 100 to 109, and 110 to 125 mg/dL, respectively. Inclusion of persons with an intermediate risk in the 100- to 109-mg/dL zone to the definition of IFG changed its positive predictive value, specificity, and sensitivity to predict diabetes from 36.5%, 94.5%, and 43.2% to 19.9%, 77.3%, and 75%, respectively. Receiver operating characteristics curve analysis including all the baseline fasting plasma glucose levels from 64 to 125 mg/dL depending on their ability to predict diabetes showed that the point closest to the ideal of 100% sensitivity and 100% specificity was 100 mg/dL. In conclusion, this study indicated that lowering the cutoff point for IFG optimizes its ability to predict diabetes in this Spanish population. The addition of other risk factors such as impaired glucose tolerance, hypertriglyceridemia, and overweight to IFG can stratify diabetes risk better.

Isolated impaired fasting glucose and peripheral insulin sensitivity: not a simple relationship

OBJECTIVE

In a recent consensus statement, the American Diabetes Association (ADA) concluded that individuals with impaired fasting glucose (IFG) have "normal muscle insulin sensitivity." To subject this conclusion to further validation, we evaluated the relationship between glucose tolerance categories and peripheral insulin sensitivity in a large nondiabetic population.

RESEARCH DESIGN AND METHODS

Insulin sensitivity was directly quantified by determining the steady-state plasma glucose (SSPG) concentration during an insulin suppression test in 446 nondiabetic individuals divided into four groups: normal glucose tolerance (NGT, n = 318), isolated IFG (n = 63), isolated impaired glucose tolerance (IGT, n = 33), and combined IFG and IGT (IFG/IGT, n = 32).

RESULTS

Insulin sensitivity was significantly different in all three groups with pre-diabetes (IFG, IGT, IFG/IGT) as compared with NGT (P < 0.05). Using tertiles of SSPG concentration in the NGT group as operational definitions of insulin resistance (highest tertile) and insulin sensitivity (lowest tertile), there was considerable heterogeneity within the pre-diabetic groups. Thus, 57% of IFG individuals were insulin resistant, and 13% were insulin sensitive. The IFG/IGT group was most homogeneous, with 94% classified as insulin resistant and only 3% as insulin sensitive.

CONCLUSIONS

Peripheral insulin sensitivity varies considerably in nondiabetic individuals, with IFG individuals showing the most heterogeneity within the pre-diabetes group. We believe that this heterogeneity in insulin sensitivity, and the relatively few patients in whom insulin sensitivity has been measured directly in the past, explain the discrepancy between our findings and those of the recent ADA consensus statement.

Combination treatment in the management of type 2 diabetes: focus on vildagliptin and metformin as a single tablet

Vildagliptin is a potent and selective inhibitor of dipeptidyl peptidase-IV (DPP-4), orally active, that improves glycemic control in patients with type 2 diabetes (T2DM) primarily by enhancing pancreatic (alpha and beta) islet function. Thus vildagliptin has been shown both to improve insulin secretion and to suppress the inappropriate glucagon secretion seen in patients with T2DM. Vildagliptin reduces HbA(1c) when given as monotherapy, without weight gain and with minimal hypoglycemia, or in combination with the most commonly prescribed classes of oral hypoglycemic drugs: metformin, a sulfonylurea, a thiazolidinedione, or insulin. Metformin, with a different mode of action not addressing beta-cell dysfunction, has been used for about 50 years and still represents the universal first line therapy of all guidelines. However, given the multiple pathophysiological abnormalities in T2DM and the progressive nature of the disease, intensification of therapy with combinations is typically required over time. Recent guidelines imply that patients will require pharmacologic combinations much earlier to attain and sustain the increasingly stringent glycemic targets, with careful drug selection to avoid unwanted adverse events, especially hypoglycemia. The combination of metformin and vildagliptin offers advantages when compared to currently used combinations with additive efficacy and complimentary mechanisms of action, since it does not increase the risk of hypoglycemia and does not promote weight gain. Therefore, by specifically combining these agents in a single tablet, there is considerable potential to achieve better blood glucose control and to improve compliance to therapy.

A cardiologist's perspective on cardiometabolic risk

Many patients who present for cardiovascular evaluation meet the National Cholesterol Education Program (NCEP) criteria for the metabolic syndrome. Indeed, the metabolic abnormalities that characterize the syndrome are major drivers of atherosclerosis. Although definitive therapeutic interventions for the metabolic syndrome remain unclear, considerable data implicate adiposity as a core element of this constellation of abnormalities. Thus, for practicing cardiologists, the need to better understand and target adiposity is inescapable.

Treatment of hypertension and other cardiovascular risk factors in patients with metabolic syndrome

Metabolic syndrome (MetS), a concurrence of hypertension, abdominal obesity, impaired fasting glucose, and dyslipidemia, has been shown to be a risk factor for cardiovascular disease. Insulin resistance has been thought to be one of the pathophysiologies of the syndrome. Reduction of the underlying causes of MetS, such as obesity, physical inactivity, and atherogenic diet, is first-line therapy. Treatment of hypertension and other cardiometabolic risk factors of MetS is also required. This article reviews the treatment of the metabolic syndrome with a focus on the importance of lifestyle changes and treatment of hypertension.

The Clamp-Like Index: a novel and highly sensitive insulin sensitivity index to calculate hyperinsulinemic clamp glucose infusion rates from oral glucose tolerance tests in nondiabetic subjects

OBJECTIVE

Insulin resistance, the underlying pathophysiological mechanism of the metabolic syndrome, can not only predict type 2 diabetes development but also cardiovascular disease. Thus, precise insulin resistance measurement in individuals at risk for metabolic diseases would support clinical risk stratification. However, the gold standard for measuring insulin resistance, the hyperinsulinemic clamp test, is too labor intensive to be performed in large clinical studies/settings.

RESEARCH DESIGN AND METHODS

Using plasma glucose and C-peptide concentrations from oral glucose tolerance tests (OGTTs), we developed the novel "clamp-like index" (CLIX) for insulin sensitivity calculation and compared CLIX to clamp glucose infusion rates (GIR) (100-120 min). We evaluated CLIX in 89 nondiabetic subjects (58 female and 31 male, aged 45 +/- 1 years, BMI 27.5 +/- 0.8 kg/m(2)) who underwent frequently sampled 3-h 75-g OGTTs and 2-h hyperinsulinemic-isoglycemic clamp (40 mU/min per m(2)) tests.

RESULTS

CLIX, calculated as serum creatinine (x0.85 if male)/(mean AUC(glucose) x mean AUC(C-peptide)) x 6,600, was highly correlated (r = 0.670, P < 10(-12)) with and comparable to clamp GIRs(100-120 min). In subgroup analyses, GIRs(100-120 min) were lower (P < 0.005) in type 2 diabetic offspring (6.2 +/- 0.7 mg x min(-1) x kg(-1)) than in sex-, age-, and BMI-matched subjects without a family history of type 2 diabetes (8.6 +/- 0.5 mg x min(-1) x kg(-1)), which was also reflected by CLIX (insulin-resistant offspring 6.4 +/- 0.6 vs. those without a family history of type 2 diabetes 9.0 +/- 0.5; P < 0.002). When compared with normal-weight subjects (GIR 8.8 +/- 0.4 mg x min(-1) x kg(-1); CLIX 9.0 +/- 0.5), both GIRs(100-120 min) and CLIX of obese (5.2 +/- 0.9 mg x min (-1) x kg(-1); 5.7 +/- 0.9) and morbidly obese (2.4 +/- 0.4 mg x min (-1) x kg(-1); 3.3 +/- 0.5) humans were lower (each P < 0.02).

CONCLUSIONS

CLIX, a novel index obtained from plasma OGTT glucose and C-peptide levels and serum creatinine, without inclusion of anthropometrical measures to calculate insulin sensitivity in nondiabetic humans, highly correlates with clamp GIRs and reveals even slight insulin sensitivity alterations over a broad BMI range and is as sensitive as the hyperinsulinemic clamp test.

Reflecting on type 2 diabetes prevention: more questions than answers!

Given the enormous public health and economic burden posed by the global epidemic of type 2 diabetes mellitus (T2DM), intervention in the prediabetes stage of disease to prevent progression to T2DM and its vascular complications seems the most sensible approach. Precisely how best to intervene remains the subject of much debate. Prudent lifestyle changes have been shown to significantly reduce the risk of progression in individuals with impaired fasting glucose (IFG) and impaired glucose tolerance (IGT). Although lifestyle modifications are notoriously difficult to maintain, there is evidence that intensive intervention results in continued preventive benefit after the stopping of structured counselling. A number of drug therapies, including metformin, acarbose, orlistat and rosiglitazone, have also been proven effective in preventing progression from IFG/IGT, but unresolved issues still remain. Specifically, whether large numbers of individuals with glucose dysregulation who may never progress to T2DM should be exposed to the risk of pharmacological adverse effects is a topic of discussion and debate. Furthermore, there are limited data on the effectiveness of implementing interventions during the prediabetic state to prevent cardiovascular complications that may be hyperglycaemia related. A recent American Diabetes Association (ADA) consensus statement on IFG/IGT recommends lifestyle modification for individuals with IFG or IGT. Of note, the ADA consensus statement introduces the option of adding metformin treatment to lifestyle changes in those individuals who have combined IFG/IGT plus an additional risk factor for progression and who also have some features that increase the likelihood of benefiting from metformin treatment. The dipeptidyl peptidase-4 inhibitors are a new class of oral antidiabetic agents that, in addition to being effective in improving glycaemic control, may exert beneficial effects in preserving beta-cell function. These characteristics, combined with a low risk of hypoglycaemia, weight neutrality and what appears - so far - to be a relatively benign tolerability profile, make these agents intriguing candidates for preventive treatment.

Direct linkage of mitochondrial genome variation to risk factors for type 2 diabetes in conplastic strains

Recently, the relationship of mitochondrial DNA (mtDNA) variants to metabolic risk factors for diabetes and other common diseases has begun to attract increasing attention. However, progress in this area has been limited because (1) the phenotypic effects of variation in the mitochondrial genome are difficult to isolate owing to confounding variation in the nuclear genome, imprinting phenomena, and environmental factors; and (2) few animal models have been available for directly investigating the effects of mtDNA variants on complex metabolic phenotypes in vivo. Substitution of different mitochondrial genomes on the same nuclear genetic background in conplastic strains provides a way to unambiguously isolate effects of the mitochondrial genome on complex traits. Here we show that conplastic strains of rats with identical nuclear genomes but divergent mitochondrial genomes that encode amino acid differences in proteins of oxidative phosphorylation exhibit differences in major metabolic risk factors for type 2 diabetes. These results (1) provide the first direct evidence linking naturally occurring variation in the mitochondrial genome, independent of variation in the nuclear genome and other confounding factors, to inherited variation in known risk factors for type 2 diabetes; and (2) establish that spontaneous variation in the mitochondrial genome per se can promote systemic metabolic disturbances relevant to the pathogenesis of common diseases.

The new clinical trials with thiazolidinediones--DREAM, ADOPT, and CHICAGO: promises fulfilled?

PURPOSE OF REVIEW

Despite extensive documentation of their insulin-sensitizing and antihyperglycemic effects, the importance and place of the thiazolidinediones in diabetes management remain unclear. Three new controlled clinical trials of thiazolidinediones offer new information on the clinical utility of these agents.

RECENT FINDINGS

During the past year, three new trials of thiazolidinediones were reported. In Diabetes Reduction Assessment with Ramipril and Rosiglitazone Medication, rosiglitazone reduced progression to diabetes in prediabetic patients by 60%. A Diabetes Outcome Progression Trial found rosiglitazone to have greater antihyperglycemic durability than metformin and glyburide in patients with recently diagnosed type 2 diabetes. Finally, in the Carotid Intima-media Thickness in Atherosclerosis using Pioglitazone, treatment with pioglitazone in patients with type 2 diabetes slowed progression of carotid wall thickness compared with the sulfonylurea glimepiride.

SUMMARY

These trials support the contention that thiazolidinediones have superior efficacy in improving and stabilizing glycemic control than older antihyperglycemic agents, especially early in the course of type 2 diabetes. Findings from the Carotid Intima-media Thickness in Atherosclerosis using Pioglitazone add to the evidence that these agents have clinically meaningful vasculoprotective effects. Although generally well tolerated, they promote weight gain, limiting their acceptability to some extent, and occasionally lead to a diagnosis of heart failure, mostly in susceptible individuals.

The effect of a community-based coronary risk reduction: the Rockford CHIP

OBJECTIVE

The aim of this study was to assess the clinical effects of a community-based lifestyle intervention program in reducing coronary risk, especially in a high risk group.

METHOD

The 40-hour educational curriculum of the Coronary Health Improvement Project (CHIP) delivered over a 30-day period with clinical and nutritional assessments before and after was offered in the spring and fall of 2000 to 2002 through the Center for Complementary Medicine of the Swedish American Health System in Rockford, Illinois to its employees and the general public. The participants were instructed to optimize their diet, quit smoking and exercise daily (walking 30 min/day).

RESULTS

The data of the 5 CHIP programs were pooled and analyzed. 544 men and 973 women (almost all Caucasian; mean age 55 years) were eligible for analysis. At the end of the 30-day intervention period, stratified analyses of total cholesterol, LDL, triglycerides, blood glucose, blood pressure and weight showed highly significant reductions with the greatest improvements among those at highest risk.

CONCLUSION

Well-designed community-based intervention programs can improve lifestyle choices and health habits. They can also markedly and rather quickly reduce the level of coronary risk factors in a non-randomized population.