Free fatty acid kinetics during long-term treatment with pioglitazone added to sulfonylurea or metformin in Type 2 diabetes

Type 2 diabetes subgroups and potential medication strategies in relation to effects on insulin resistance and beta-cell function: A step toward personalised diabetes treatment?

Background

Type 2 diabetes is a syndrome defined by hyperglycaemia that is the result of various degrees of pancreatic β-cell failure and reduced insulin sensitivity. Although diabetes can be caused by multiple metabolic dysfunctions, most patients are defined as having either type 1 or type 2 diabetes. Recently, Ahlqvist and colleagues proposed a new method of classifying patients with adult-onset diabetes, considering the heterogenous metabolic phenotype of the disease. This new classification system could be useful for more personalised treatment based on the underlying metabolic disruption of the disease, although to date no prospective intervention studies have generated data to support such a claim.

Scope of Review

In this review, we first provide a short overview of the phenotype and pathogenesis of type 2 diabetes and discuss the current and new classification systems. We then review the effects of different anti-diabetic medication classes on insulin sensitivity and β-cell function and discuss future treatment strategies based on the subgroups proposed by Ahlqvist et al.

Major Conclusions

The proposed novel type 2 diabetes subgroups provide an interesting concept that could lead to a better understanding of the pathophysiology of the broad group of type 2 diabetes, paving the way for personalised treatment choices based on understanding the root cause of the disease. We conclude that the novel subgroups of adult-onset diabetes would benefit from anti-diabetic medications that take into account the main pathophysiology of the disease and thereby prevent end-organ damage. However, we are only beginning to address the personalised treatment of type 2 diabetes, and studies investigating the effects of current and novel drugs in subgroups with different metabolic phenotypes are needed to develop personalised treatment of the syndrome

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Novel subgroups of type 2 diabetes provide a concept that could lead to a better understanding of its pathophysiology.

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Treatment strategies would benefit from anti-diabetic medications that influence the main pathophysiology of diabetes.

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Here, we review different anti-diabetic medications classes affecting insulin sensitivity and β-cell function.

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We suggest that future treatment strategies could benefit by taking into account subgroups provided by Ahlqvist et al.

Metformin and second- or third-generation sulphonylurea combination therapy for adults with type 2 diabetes mellitus

BACKGROUND

The number of people with type 2 diabetes mellitus (T2DM) is increasing worldwide. The combination of metformin and sulphonylurea (M+S) is a widely used treatment. Whether M+S shows better or worse effects in comparison with other antidiabetic medications for people with T2DM is still controversial.

OBJECTIVES

To assess the effects of metformin and sulphonylurea (second- or third-generation) combination therapy for adults with type 2 diabetes mellitus.

SEARCH METHODS

We updated the search of a recent systematic review from the Agency for Healthcare Research and Quality (AHRQ). The updated search included CENTRAL, MEDLINE, Embase, ClinicalTrials.gov and WHO ICTRP. The date of the last search was March 2018. We searched manufacturers' websites and reference lists of included trials, systematic reviews, meta-analyses and health technology assessment reports. We asked investigators of the included trials for information about additional trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) randomising participants 18 years old or more with T2DM to M+S compared with metformin plus another glucose-lowering intervention or metformin monotherapy with a treatment duration of 52 weeks or more.

DATA COLLECTION AND ANALYSIS

Two review authors read all abstracts and full-text articles and records, assessed risk of bias and extracted outcome data independently. We used a random-effects model to perform meta-analysis, and calculated risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes, using 95% confidence intervals (CIs) for effect estimates. We assessed the certainty of the evidence using the GRADE instrument.

MAIN RESULTS

We included 32 RCTs randomising 28,746 people. Treatment duration ranged between one to four years. We judged none of these trials as low risk of bias for all 'Risk of bias' domains. Most important events per person were all-cause and cardiovascular mortality, serious adverse events (SAE), non-fatal stroke (NFS), non-fatal myocardial infarction (MI) and microvascular complications. Most important comparisons were as follows:Five trials compared M+S (N = 1194) with metformin plus a glucagon-like peptide 1 analogue (N = 1675): all-cause mortality was 11/1057 (1%) versus 11/1537 (0.7%), risk ratio (RR) 1.15 (95% confidence interval (CI) 0.49 to 2.67); 3 trials; 2594 participants; low-certainty evidence; cardiovascular mortality 1/307 (0.3%) versus 1/302 (0.3%), low-certainty evidence; serious adverse events (SAE) 128/1057 (12.1%) versus 194/1537 (12.6%), RR 0.90 (95% CI 0.73 to 1.11); 3 trials; 2594 participants; very low-certainty evidence; non-fatal myocardial infarction (MI) 2/549 (0.4%) versus 6/1026 (0.6%), RR 0.57 (95% CI 0.12 to 2.82); 2 trials; 1575 participants; very low-certainty evidence.Nine trials compared M+S (N = 5414) with metformin plus a dipeptidyl-peptidase 4 inhibitor (N = 6346): all-cause mortality was 33/5387 (0.6%) versus 26/6307 (0.4%), RR 1.32 (95% CI 0.76 to 2.28); 9 trials; 11,694 participants; low-certainty evidence; cardiovascular mortality 11/2989 (0.4%) versus 9/3885 (0.2%), RR 1.54 (95% CI 0.63 to 3.79); 6 trials; 6874 participants; low-certainty evidence; SAE 735/5387 (13.6%) versus 779/6307 (12.4%), RR 1.07 (95% CI 0.97 to 1.18); 9 trials; 11,694 participants; very low-certainty evidence; NFS 14/2098 (0.7%) versus 8/2995 (0.3%), RR 2.21 (95% CI 0.74 to 6.58); 4 trials; 5093 participants; very low-certainty evidence; non-fatal MI 15/2989 (0.5%) versus 13/3885 (0.3%), RR 1.45 (95% CI 0.69 to 3.07); 6 trials; 6874 participants; very low-certainty evidence; one trial in 64 participants reported no microvascular complications were observed (very low-certainty evidence).Eleven trials compared M+S (N = 3626) with metformin plus a thiazolidinedione (N = 3685): all-cause mortality was 123/3300 (3.7%) versus 114/3354 (3.4%), RR 1.09 (95% CI 0.85 to 1.40); 6 trials; 6654 participants; low-certainty evidence; cardiovascular mortality 37/2946 (1.3%) versus 41/2994 (1.4%), RR 0.78 (95% CI 0.36 to 1.67); 4 trials; 5940 participants; low-certainty evidence; SAE 666/3300 (20.2%) versus 671/3354 (20%), RR 1.01 (95% CI 0.93 to 1.11); 6 trials; 6654 participants; very low-certainty evidence; NFS 20/1540 (1.3%) versus 16/1583 (1%), RR 1.29 (95% CI 0.67 to 2.47); P = 0.45; 2 trials; 3123 participants; very low-certainty evidence; non-fatal MI 25/1841 (1.4%) versus 21/1877 (1.1%), RR 1.21 (95% CI 0.68 to 2.14); P = 0.51; 3 trials; 3718 participants; very low-certainty evidence; three trials (3123 participants) reported no microvascular complications (very low-certainty evidence).Three trials compared M+S (N = 462) with metformin plus a glinide (N = 476): one person died in each intervention group (3 trials; 874 participants; low-certainty evidence); no cardiovascular mortality (2 trials; 446 participants; low-certainty evidence); SAE 34/424 (8%) versus 27/450 (6%), RR 1.68 (95% CI 0.54 to 5.21); P = 0.37; 3 trials; 874 participants; low-certainty evidence; no NFS (1 trial; 233 participants; very low-certainty evidence); non-fatal MI 2/215 (0.9%) participants in the M+S group; 2 trials; 446 participants; low-certainty evidence; no microvascular complications (1 trial; 233 participants; low-certainty evidence).Four trials compared M+S (N = 2109) with metformin plus a sodium-glucose co-transporter 2 inhibitor (N = 3032): all-cause mortality was 13/2107 (0.6%) versus 19/3027 (0.6%), RR 0.96 (95% CI 0.44 to 2.09); 4 trials; 5134 participants; very low-certainty evidence; cardiovascular mortality 4/1327 (0.3%) versus 6/2262 (0.3%), RR 1.22 (95% CI 0.33 to 4.41); 3 trials; 3589 participants; very low-certainty evidence; SAE 315/2107 (15.5%) versus 375/3027 (12.4%), RR 1.02 (95% CI 0.76 to 1.37); 4 trials; 5134 participants; very low-certainty evidence; NFS 3/919 (0.3%) versus 7/1856 (0.4%), RR 0.87 (95% CI 0.22 to 3.34); 2 trials; 2775 participants; very low-certainty evidence; non-fatal MI 7/890 (0.8%) versus 8/1374 (0.6%), RR 1.43 (95% CI 0.49 to 4.18; 2 trials); 2264 participants; very low-certainty evidence; amputation of lower extremity 1/437 (0.2%) versus 1/888 (0.1%); very low-certainty evidence.Trials reported more hypoglycaemic episodes with M+S combination compared to all other metformin-antidiabetic agent combinations. Results for M+S versus metformin monotherapy were inconclusive. There were no RCTs comparing M+S with metformin plus insulin. We identified nine ongoing trials and two trials are awaiting assessment. Together these trials will include approximately 16,631 participants.

AUTHORS' CONCLUSIONS

There is inconclusive evidence whether M+S combination therapy compared with metformin plus another glucose-lowering intervention results in benefit or harm for most patient-important outcomes (mortality, SAEs, macrovascular and microvascular complications) with the exception of hypoglycaemia (more harm for M+S combination). No RCT reported on health-related quality of life.

Sex- and age-related differences of metabolic parameters in impaired glucose metabolism and type 2 diabetes compared to normal glucose tolerance

AIMS

This study analysed potential sex differences in glucose metabolism of European subjects with different degrees of glucose tolerance impairment.

METHODS

Subjects with impaired glucose metabolism, IGM (n = 735), or type 2 diabetes, T2DM (n = 415), were compared to subjects with normal glucose tolerance, NGT (n = 422), with similar BMI. For both males (M) and females (F), 50 years threshold was used for estimation of menopausal/andropausal state. Subjects underwent 75-g OGTT for measurements of insulin sensitivity (OGIS), beta-cell function (insulinogenic index, IGI_C), and overall metabolic condition, disposition index (DI).

RESULTS

In IGM, OGIS did not change with age in both sexes, whereas marked reduction of IGI_C was seen in F (p = 0.0003). In T2DM, again OGIS did not change with age, but M ≥ 50 yrs had reduced IGI_C and DI (p < 0.002) compared to M < 50 yrs.

CONCLUSIONS

IGM did not reveal relevant changes of insulin resistance with age, but early phase insulin release deteriorated, with higher change in women. T2DM men featured age-related deterioration of glucose metabolism. In women, sex advantage seen in NGT vanished in T2DM, since glucose metabolism was overall not different than in men, both young and elderly.

Meal-derived glucagon responses are related to lower hepatic phosphate concentrations in obesity and type 2 diabetes

AIM

Type 2 diabetes (T2D) alters glucagon, glucagon-like peptide (GLP)-1, glucose-dependent insulinotropic polypeptide (GIP) and hepatic energy metabolism, yet the possible relationships remain unclear.

METHODS

In this observational study, lean insulin-sensitive control subjects (BMI: 23.2±1.5kg/m²), age-matched insulin-resistant obese subjects (BMI: 34.3±1.7kg/m²) and similarly obese elderly T2D patients (BMI: 32.0±2.4kg/m²) underwent mixed-meal tolerance tests (MMTTs), and assessment of hepatic γATP, inorganic phosphate (P_i) and lipids using ³¹P/¹H magnetic resonance spectroscopy. Meal-induced secretion of glucagon and incretins was calculated from incremental areas under the concentration-time curves (iAUCs). Peripheral and adipose tissue insulin sensitivity were assessed from time courses of circulating glucose, insulin and free fatty acids.

RESULTS

MMTT-derived peripheral insulin sensitivity was lowest in T2D patients (P<0.001), while glucagon concentrations were comparable across all three groups. At 260min, GLP-1 was lower in T2D patients than in controls, whereas GIP was lowest in obese individuals. Fasting glucagon concentrations correlated positively with fasting (r=0.60) and postprandial hepatocellular lipid levels (160min: r=0.51, 240min: r=0.59), and negatively with adipose tissue insulin sensitivity (r=-0.73). Higher meal-induced glucagon release (iAUC_0-260min) correlated with lower fasting (r=-0.62) and postprandial P_i levels (160min: r=-0.43, 240min: r=-0.42; all P<0.05). Higher meal-induced release of GIP (iAUC_0-260min) correlated positively with fasting (r=0.54) and postprandial serum triglyceride concentrations (iAUC_0-260min, r=0.54; all P<0.01).

CONCLUSION

Correlations between fasting glucagon and hepatic lipids and between meal-induced glucagon and hepatic P_i suggest a role for glucagon in hepatic energy metabolism.

Free Fatty Acid Is Associated with Thrombogenicity in Cardioembolic Stroke

Background: Recently, the role of free fatty acids (FFAs) in thromboembolism has re-emerged in the context of cardioembolic stroke. Therefore, we attempted to determine the role of FFAs in embolic risk in various potential sources of cardioembolism (PSCE). We hypothesized that if elevated FFA levels in stroke patients are associated with thrombogenesis, then patients with a well-known high risk of embolic sources would have high FFA levels. Methods: Data collected from 2 hospital-based stroke registries were analyzed to investigate the association between FFA and PSCE. Results: A total of 2,770 acute stroke patients, including 539 with cardioembolic stroke, were selected for analysis. FFA was an independent predictor for cardioembolism (OR 2.755, 95% CI 2.221-3.417, p < 0.001). Among the PSCE, FFA levels were significantly associated with high risk of atrial fibrillation (AF), valvular heart disease, congestive heart failure with low ejection fraction, left atrial thrombus, left ventricular thrombus, left atrial smoke, and ventricular wall motion abnormality. FFA levels increased with the number of PSCE per patient without interaction with the presence of AF. Conclusions: Among acute stroke patients, FFA levels increased in groups with higher risk of cardioembolic stroke irrespective of the presence of AF. These results suggest that enhanced thrombogenicity could be the main mechanism to explain the elevated FFA levels in patients with cardioembolic stroke.

Glucose metabolism after renal transplantation

OBJECTIVE

We determined prevalence, risk factors, phenotype, and pathophysiological mechanism of new-onset diabetes after transplantation (NODAT) to generate strategies for optimal pharmacological management of hyperglycemia in NODAT patients.

RESEARCH DESIGN AND METHODS

Retrospective cohort study comparing demographics, laboratory data, and oral glucose tolerance test (OGTT)-derived metabolic parameters from kidney transplant recipients versus subjects not receiving transplants.

RESULTS

Among 1,064 stable kidney transplant recipients (≥ 6 months posttransplantation), 113 (11%) had a history of NODAT and 132 (12%) had pretransplant diabetes. In the remaining patients, randomly assigned OGTTs showed a high prevalence of abnormal glucose metabolism (11% diabetes; 32% impaired fasting glucose, impaired glucose tolerance, or both), predominantly in older patients who received tacrolimus as the primary immunosuppressant. Compared with 1,357 nontransplant subjects, stable kidney transplant recipients had lower basal glucose, higher glycated hemoglobin, lower insulin secretion, and greater insulin sensitivity in each of the three subgroups, defined by OGTT 2-h glucose (<140, 140-199, ≥ 200 mg/dL). These findings were reinforced in linear spline interpolation models of insulin secretion and sensitivity (all P < 0.001) and in another regression model in which the estimated oral glucose insulin sensitivity index was substantially higher (by 79-112 mL/min m(2)) for transplant versus nontransplant subjects despite adjustments for age, sex, and BMI (all P < 0.001).

CONCLUSIONS

Glucose metabolism differs substantially between kidney transplant recipients and nontransplant controls. Because impaired insulin secretion appears to be the predominant pathophysiological feature after renal transplantation, early therapeutic interventions that preserve, maintain, or improve β-cell function are potentially beneficial in this population.

Influence of increasing BMI on insulin sensitivity and secretion in normotolerant men and women of a wide age span

The impact of sex and age on glucose metabolism in the development of overweight/obesity is a matter of debate. We hypothesized that insulin sensitivity (IS) and β-cell function (BF) in a normal white population will differ between males and females and aimed to evaluate the possible effects of BMI and age on metabolic parameters of both sexes. This study is a cross-sectional analysis of the general community. IS was measured with quantitative insulin sensitivity check index (QUICKI) and oral glucose insulin sensitivity (OGIS) and BF with the insulinogenic index during 75-g 2-h oral glucose-tolerance tests (OGTTs). We studied 611 females and 361 males with normal glycemia according to both fasting and 2-h glucose (85 ± 0.3 mg/dl (means ± SE) in females and 89 ± 0.4 in males (P < 0.0001), and 93 ± 1 in females and 89 ± 1 in males (P = 0.005), respectively). Females were younger (37 ± 1 years) than males (40 ± 1, P < 0.0001), but no difference was found in mean BMI (BMI = 25.8 ± 0.2 kg/m(2) in both). Student's two-sample t-test was used for simple comparison between and within genders, multiple linear regressions to account for covariates. During the OGTT, females had lower glucose (area under the curve (AUC) 133 ± 1 mg/ml·2 h vs. 148 ± 2; P < 0.00001), while insulinemia was comparable (AUC 5.3 ± 0.1 mU/ml·2 h vs. 5.7 ± 0.2, P = 0.15). IS remained higher in females (473 ± 3 ml/min/m(2) vs. 454 ± 3, P < 0.0001) also after having accounted for age and BMI (P = 0.015). No difference was observed in fasting insulin or BF. However, BF increased by 46% with BMI and when accounting for age and BMI, BF of females was significantly higher (P < 0.0001). Because IS and BF are higher in females than in males, sex should be considered in metabolic studies and overweight/obese populations.

Plasma fatty acid-binding protein 4, nonesterified fatty acids, and incident diabetes in older adults

OBJECTIVE

To examine the relation of fatty acid-binding protein (FABP)4 and nonesterified fatty acids (NEFAs) to diabetes in older adults.

RESEARCH DESIGN AND METHODS

We ascertained incident diabetes among 3,740 Cardiovascular Health Study participants (1992-2007) based on the use of hypoglycemic medications, fasting glucose ≥ 126 mg/dL, or nonfasting glucose ≥ 200 mg/dL. FABP4 and NEFA were measured on specimens collected between 1992 and 1993.

RESULTS

Mean age of the 3,740 subjects studied was 74.8 years. For each SD increase in log FABP4, hazard ratios (HRs) for diabetes were 1.35 (95% CI 1.10-1.65) for women and 1.45 (1.13-1.85) for men controlling for age, race, education, physical activity, cystatin C, alcohol intake, smoking, self-reported health status, and estrogen use for women (P for sex-FABP4 interaction 0.10). BMI modified the FABP4-diabetes relation (P = 0.009 overall; 0.02 for women and 0.135 for men), in that statistically significant higher risk of diabetes was mainly seen in men with BMI <25 kg/m(2) (HR per SD: 1.78 [95% CI 1.13-2.81]). There was a modest and nonsignificant association of NEFA with diabetes (P(trend) = 0.21). However, when restricted to the first 5 years of follow-up, multivariable-adjusted HRs for diabetes were 1.0 (ref.), 1.68 (95% CI 1.12-2.53), and 1.63 (1.07-2.50) across consecutive tertiles of NEFA (P(trend) = 0.03).

CONCLUSIONS

Plasma FABP4 was positively associated with incident diabetes in older adults, and such association was statistically significant in lean men only. A significant positive association between plasma NEFA and incident diabetes was observed during the first 5 years of follow-up.

Non-esterified fatty acid dynamics during oral glucose tolerance test in women with former gestational diabetes

AIMS

Women with former gestational diabetes are at increased risk of Type 2 diabetes, which likely relates to hyperlipidaemia and ectopic lipid storage, mainly in the liver. Here, we examined the response of non-esterified fatty acid dynamics to oral glucose loading (oral glucose tolerance test).

METHODS

We studied women with former gestational diabetes with normal glucose tolerance (n = 60) or impaired glucose metabolism (n = 12) and compared them with healthy women after normal pregnancy (control subjects, n = 15). During a 3-h oral glucose tolerance test, glucose, insulin and non-esterified fatty acid were frequently measured to compute the area under the non-esterified fatty acid curve and parameters of β-cell function and insulin sensitivity. Through mathematical modelling, we assessed insulin sensitivity of lipolysis inhibition and the fractional non-esterified fatty acid turnover rate. We also measured some serum liver enzymes.

RESULTS

Women with former gestational diabetes were slightly older and had greater body mass than control subjects. Subjects with impaired glucose metabolism had lower oral glucose insulin sensitivity, but higher fasting insulin and area under the non-esterified fatty acid curve, which inversely related to oral glucose insulin sensitivity and independently determined mean glycaemia. Model-derived non-esterified fatty acid parameters were lower in subjects with impaired glucose metabolism than in control subjects, particularly sensitivity of non-esterified fatty acid inhibition to insulin (2.50 ± 0.52 vs. 1.06 ± 0.20 · 10(-2) ml/μU). Also, subjects with impaired glucose metabolism had higher liver transaminases. However, all non-esterified fatty acid parameters showed only modest inverse correlation with liver transaminases.

CONCLUSIONS

Despite greater insulinaemia, circulating non-esterified fatty acids are higher in women with former gestational diabetes than in control subjects, which likely results from reduced sensitivity of lipolysis inhibition to insulin. This parameter may serve as indicator of an early metabolic derangement in this population at risk for diabetes.

Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus

BACKGROUND

Metformin is an oral anti-hyperglycemic agent that has been shown to reduce total mortality compared to other anti-hyperglycemic agents, in the treatment of type 2 diabetes mellitus. Metformin, however, is thought to increase the risk of lactic acidosis, and has been considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age.

OBJECTIVES

To assess the incidence of fatal and nonfatal lactic acidosis, and to evaluate blood lactate levels, for those on metformin treatment compared to placebo or non-metformin therapies.

SEARCH STRATEGY

A comprehensive search was performed of electronic databases to identify studies of metformin treatment. The search was augmented by scanning references of identified articles, and by contacting principal investigators.

SELECTION CRITERIA

Prospective trials and observational cohort studies in patients with type 2 diabetes of least one month duration were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy.

DATA COLLECTION AND ANALYSIS

The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for non-metformin treatments. The upper limit for the true incidence of cases was calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed-effect model for continuous data.

MAIN RESULTS

Pooled data from 347 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 70,490 patient-years of metformin use or in 55,451 patients-years in the non-metformin group. Using Poisson statistics the upper limit for the true incidence of lactic acidosis per 100,000 patient-years was 4.3 cases in the metformin group and 5.4 cases in the non-metformin group. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to non-metformin therapies.

AUTHORS' CONCLUSIONS

There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments.

Pioglitazone and mechanisms of CV protection

BACKGROUND AND AIM

Pioglitazone has diverse multiple effects on metabolic and inflammatory processes that have the potential to influence cardiovascular disease pathophysiology at various points in the disease process, including atherogenesis, plaque inflammation, plaque rupture, haemostatic disturbances and microangiopathy.

RESULTS

Linking the many direct and indirect effects on the vasculature to the reduction in key macrovascular outcomes reported with pioglitazone in patients with type 2 diabetes presents a considerable challenge. However, recent large-scale clinical cardiovascular imaging studies are beginning to provide some mechanistic insights, including a potentially important role for improvements in high-density lipoprotein cholesterol with pioglitazone. In addition to a role in prevention, animal studies also suggest that pioglitazone may minimize damage and improve recovery during and after ischaemic cardio- and cerebrovascular events.

DESIGN AND METHODS

In this review, we consider potential cardiovascular protective mechanisms of pioglitazone by linking preclinical data and clinical cardiovascular outcomes guided by insights from recent imaging studies.

CONCLUSION

Pioglitazone may influence CVD pathophysiology at multiple points in the disease process, including atherogenesis, plaque inflammation, plaque rupture and haemostatic disturbances (i.e. thrombus/embolism formation), as well as microangiopathy.

Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus

BACKGROUND

Metformin is an oral anti-hyperglycemic agent that has been shown to reduce total mortality compared to other anti-hyperglycemic agents, in the treatment of type 2 diabetes mellitus. Metformin, however, is thought to increase the risk of lactic acidosis, and has been considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age.

OBJECTIVES

To assess the incidence of fatal and nonfatal lactic acidosis, and to evaluate blood lactate levels, for those on metformin treatment compared to placebo or non-metformin therapies.

SEARCH STRATEGY

A comprehensive search was performed of electronic databases to identify studies of metformin treatment. The search was augmented by scanning references of identified articles, and by contacting principal investigators.

SELECTION CRITERIA

Prospective trials and observational cohort studies in patients with type 2 diabetes of least one month duration were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy.

DATA COLLECTION AND ANALYSIS

The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for non-metformin treatments. The upper limit for the true incidence of cases was calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed-effect model for continuous data.

MAIN RESULTS

Pooled data from 347 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 70,490 patient-years of metformin use or in 55,451 patients-years in the non-metformin group. Using Poisson statistics the upper limit for the true incidence of lactic acidosis per 100,000 patient-years was 4.3 cases in the metformin group and 5.4 cases in the non-metformin group. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to non-metformin therapies.

AUTHORS' CONCLUSIONS

There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments.