Incidence of coronary heart disease in type 2 diabetic men and women: impact of microvascular complications, treatment, and geographic location

Aspirin for primary prevention of cardiovascular events in people with diabetes: meta-analysis of randomised controlled trials

OBJECTIVE

To evaluate the benefits and harms of low dose aspirin in people with diabetes and no cardiovascular disease.

DESIGN

Meta-analysis of randomised controlled trials.

DATA SOURCES

Medline (1966-November 2008), the Cochrane central register of controlled trials (Cochrane Library 2008;issue 4), and reference lists of retrieved articles. Review methods Randomised trials of aspirin compared with placebo or no aspirin in people with diabetes and no pre-existing cardiovascular disease were eligible for inclusion. Data on major cardiovascular events (death from cardiovascular causes, non-fatal myocardial infarction, non-fatal stroke, and all cause mortality) were extracted and pooled with a random effect model. Results are reported as relative risks with 95% confidence intervals.

RESULTS

Of 157 studies in the literature searches, six were eligible (10 117 participants). When aspirin was compared with placebo there was no statistically significant reduction in the risk of major cardiovascular events (five studies, 9584 participants; relative risk 0.90, 95% confidence interval 0.81 to 1.00), cardiovascular mortality (four studies, n=8557, 0.94; 0.72 to 1.23), or all cause mortality (four studies, n=8557; 0.93, 0.82 to 1.05). Significant heterogeneity was found in the analysis for myocardial infarction (I(2)=62.2%; P=0.02) and stroke (I(2)=52.5%; P=0.08). Aspirin significantly reduced the risk of myocardial infarction in men (0.57, 0.34 to 0.94) but not in women (1.08, 0.71 to 1.65; P for interaction=0.056). Evidence relating to harms was inconsistent.

CONCLUSIONS

A clear benefit of aspirin in the primary prevention of major cardiovascular events in people with diabetes remains unproved. Sex may be an important effect modifier. Toxicity is to be explored further.

Higher HDL cholesterol levels are associated with a lower incidence of chronic kidney disease in patients with type 2 diabetes

BACKGROUND AND AIMS

Type 2 diabetes is one of the most important risk factor for the development of chronic kidney disease (CKD). Recently, it has been shown that lower high-density lipoprotein cholesterol (HDL-C) levels predicted the development of microalbuminuria in type 2 diabetic individuals. We have prospectively assessed the effects of plasma HDL-C levels on the incidence of CKD in a large cohort of type 2 diabetic patients.

METHODS AND RESULTS

We followed 1987 type 2 diabetic outpatients with normal or near-normal kidney function at baseline for 5 years for the occurrence of incident CKD defined as glomerular filtration rate < or = 60 mL/min/1.73 m(2) (as estimated by the abbreviated Modified Diet and Renal Disease Study equation). Cox proportional hazards models were used to examine the independent relationship between plasma HDL-C levels and incident CKD. During a median follow-up of 5 years, 11.8% (n=234) of participants developed incident CKD. In multivariate regression analysis, higher HDL-C levels were associated with a lower risk of incident CKD (multiple-adjusted hazard ratio 0.76; 95% coefficient intervals 0.61-0.96; p=0.025) independently of age, gender, body mass index, hypertension, smoking history, diabetes duration, hemoglobin A1c, plasma triglycerides, LDL-cholesterol, presence of diabetic retinopathy, baseline albuminuria, and current use of medications (anti-hypertensive, anti-platelet, lipid-lowering and hypoglycemic drugs).

CONCLUSIONS

Higher plasma levels of HDL-C are associated with a lower risk of incident CKD in a large cohort of type 2 diabetic adults independently of numerous confounding factors.

Effect of tight control of HbA1c and blood pressure on cardiovascular diseases in type 2 diabetes: an observational study from the Swedish National Diabetes Register (NDR)

AIM

To estimate hazard ratio (HR) of first incident fatal/non-fatal cardiovascular diseases (CVD) in female/male type 2 diabetic patients, with tight versus adverse control of HbA1c and blood pressure (BP) at baseline, age 30-70 years, no baseline CVD, followed for mean 5.7 years.

METHODS

2593 patients with tight control of HbA1c <7.5% and BP < or = 140/90 mmHg (median 6.5%/130/80 mmHg), and 2160 patients with adverse control 7.5-9.0%/141-190/91-110 mmHg (median 8.1%/155/85 mmHg).

RESULTS

The hazard ratio (HR) for CVD with tight/adverse control was 0.67 (0.55-0.80; p<0.001), adjusting for age, sex, duration, hypoglycaemic treatment, smoking, BMI, lipid-lowering drugs, antihypertensive drugs, microalbuminuria. Adjusted HR for myocardial infarction, coronary heart disease, stroke and total mortality were 0.72 (0.56-0.92; p=0.01), 0.69 (0.55-0.86; p<0.001), 0.62 (0.45-0.84; p<0.001), 1.00 (0.72-1.39). The partial population-attributable risk percent for myocardial infarction, stroke and CVD was 23%, 33%, 29% if adverse HbA1c/BP control could be avoided, while 43%, 38%, 39% with overweight and smoking also avoided. Baseline lower BMI and absence of microalbuminuria were associated with tight control.

CONCLUSION

Median difference of HbA1c/BP 1.6%/25/5 mmHg between tight and adverse control considerably reduced the risk of cardiovascular diseases. The findings call for a multi-factorial approach to improve HbA1c, BP, obesity, smoking, and microalbuminuria.

Decreased whole body lipolysis as a mechanism of the lipid-lowering effect of pioglitazone in type 2 diabetic patients

Pioglitazone has been shown to reduce fasting triglyceride levels. The mechanisms of this effect have not been fully elucidated, but decreased lipolysis may contribute to blunt the hypertriglyceridemic response to a meal. To test this hypothesis, we studied 27 type 2 diabetes mellitus (T2DM) patients and 7 sex-, age-, and body mass index-matched nondiabetic controls. Patients were randomized to pioglitazone (45 mg/day) or placebo for 16 wk. Whole body lipolysis was measured [as the [(2)H(5)]glycerol rate of appearance (R(a))] in the fasting state and for 6 h following a mixed meal. Compared with controls, T2DM had higher postprandial profiles of plasma triglycerides, free fatty acid (FFA), and beta-hydroxybutyrate, and a decreased suppression of glycerol R(a) (P < 0.04) despite higher insulin levels [268 (156) vs. 190 (123) pmol/l, median (interquartile range)]. Following pioglitazone, triglycerides and FFA were reduced (P = 0.05 and P < 0.04, respectively), and glycerol R(a) was more suppressed [-40 (137) vs. +7 (202) mumol/min of placebo, P < 0.05] despite a greater fall in insulin [-85 (176) vs. -20 (58) pmol/l, P = 0.05]. We conclude that, in well-controlled T2DM patients, whole body lipolysis is insulin resistant, and pioglitazone improves the insulin sensitivity of lipolysis.

Economic outcomes associated with microvascular complications of type 2 diabetes mellitus: results from a US claims data analysis

BACKGROUND

Patients with diabetes mellitus have been shown to be at high risk for both macrovascular and microvascular complications (MVC). Recent studies have focused on MVC and their effect on the healthcare system, but limited published data exist on long-term costs associated with MVC in patients with type 2 diabetes mellitus (T2DM).

OBJECTIVE

The objective of this study was to compare resource utilization and medical costs over a 12-month period among patients diagnosed with T2DM with versus without MVC in a managed-care population.

METHODS

Patients aged >/=18 years, diagnosed with T2DM between 1 January 2003 and 31 December 2004 were identified in an administrative claims database of approximately 55 million beneficiaries in private and public health plans. The date of the first T2DM diagnosis during this period was the 'index date' for each patient. All patients had to have a minimum of 12 months of continuous enrolment both prior to and following the index date. MVC was identified during the 12 months prior to the first T2DM diagnosis and these patients were matched (1 : 2) by age, sex and ten co-morbid conditions to those with no evidence of MVC during the entire study period.

RESULTS

Among the 15 326 MVC patients included in the study, 61% had a history of peripheral neuropathy, 28% diabetic retinopathy and 19% nephropathy. Compared with 30 652 patients without MVC, the MVC patients were more likely to use oral antidiabetics and insulin and had a higher co-morbidity score. Over 12 months, patients with MVC had more (mean 0.3 vs 0.2; p < 0.001) and longer (mean length of stay 1.79 days vs 0.85 days; p < 0.001) hospital stays; physician office visits (19.7 vs 13.7; p < 0.001); and prescriptions for oral antidiabetic (6.3 vs 5.6 scripts; p < 0.001) and insulin (0.7 vs 0.2 scripts; p < 0.001) use. Average total costs per patient over 12 months were $US14 414 with MVC versus $US8669 without MVC (p < 0.001).

CONCLUSIONS

This study indicates that in patients with T2DM, MVC is associated with significant consumption of healthcare resources. Mean total costs with MVC were almost double those of patients without MVC over a 12-month period.

Recurrence of cardiovascular events in patients with type 2 diabetes: epidemiology and risk factors

OBJECTIVE

The purpose of this study was to assess incidence of and risk factors for recurrent cardiovascular disease (CVD) in type 2 diabetes.

RESEARCH DESIGN AND METHODS

We estimated the incidence of recurrent cardiovascular events in type 2 diabetic patients, aged 40-97 years, followed by a network of diabetes clinics. The analysis was conducted separately for 2,788 patients with CVD at enrollment (cohort A) and for 844 patients developing the first episode during the observation period (cohort B).

RESULTS

During 4 years of follow-up, in cohort A the age-adjusted incidence of a recurrent event (per 1,000 person-years) was 72.7 (95% CI 58.3-87.1) in men and 32.5 (21.2-43.7) in women, whereas in cohort B it was 40.1 (17.4-62.9) in men and 22.4 (12.9-32.0) in women. After controls were included for potential predictors (familial CVD, obesity, smoking, diabetes duration, glycemic control, microvascular complications, geographic area, and antihypertensive and lipid-lowering treatment), male sex, older age, and insulin use were significant independent risk predictors (cohort A) and serum triglyceride levels >/=1.69 mmol/l emerged as the only metabolic (negative) prognostic factor (cohort B). In both cohorts, a prior CVD episode, especially myocardial infarction, was by far the strongest predictor of recurrent CVD.

CONCLUSIONS

Approximately 6% of unselected diabetic patients in secondary prevention develop recurrent major CVD every year. Those with long-standing previous CVD show a higher incidence of recurrence. Male sex, age, high triglyceride levels, and insulin use are additional predictors of recurrence.

Risk of myocardial infarction in men and women with type 2 diabetes in the UK: a cohort study using the General Practice Research Database

AIMS/HYPOTHESIS

Our primary aim was to establish reliable and generalisable estimates of the risk of myocardial infarction (MI) for men and women with type 2 diabetes in the UK compared with people without diabetes. Our secondary aim was to investigate how the MI risk associated with diabetes differs between men and women.

METHODS

A cohort study using the General Practice Research Database (1992-1999) was carried out, selecting 40,727 patients with type 2 diabetes and 194,913 age and sex-matched patients without diabetes. Rates of MI in men and women with and without diabetes were derived, as were hazard ratios for MI adjusted for known risk factors.

RESULTS

The rate of MI in men with type 2 diabetes was 19.74 (95% CI 18.83-20.69) per 1,000 person-years compared with 16.18 (95% CI 15.33-17.08) per 1,000 person-years in women with type 2 diabetes. The overall adjusted relative risk of MI in diabetes versus no diabetes was 2.13 (95% CI 2.01-2.26) in men and 2.95 (95% CI 2.75-3.17) in women and decreased with age in both sexes. Women with type 2 diabetes aged 35 to 54 years were at almost five times the risk of MI compared with women of the same age without diabetes (HR 4.86 [95% CI 2.78-8.51]).

CONCLUSIONS/INTERPRETATION

This study has demonstrated that women with type 2 diabetes are at a much greater relative risk of MI than men even when adjusted for risk factors.

Role of microRNAs in diabetes

Diabetes is one of the most common chronic diseases in the world. Multiple and complex factors including various genetic and physiological changes can lead to type 1 and type 2 diabetes. However, the major mechanisms underlying the pathogenesis of diabetes remain obscure. With the recent discovery of microRNAs (miRNAs), these small ribonucleotides have been implicated as new players in the pathogenesis of diabetes and diabetes-associated complications. MiRNAs have been shown to regulate insulin production, insulin secretion, and insulin action. This review summarizes the recent progress in the cutting-edge research of miRNAs involved in diabetes and diabetes related complications.

Clinical significance of HbA1c as a marker of circulating lipids in male and female type 2 diabetic patients

Diabetic patients with accompanied (but often unnoticed) dyslipidemia are soft targets of cardiovascular deaths. An early intervention to normalize circulating lipids has been shown to reduce cardiovascular complications and mortality. Glycated hemoglobin (HbA(1c)) is a routinely used marker for long-term glycemic control. This investigation is an attempt to evaluate the diagnostic value of HbA(1c) in predicting diabetic dyslipidemia. Venous blood samples were collected from 2,220 type 2 diabetic patients (ages, 35-91 years; male/female ratio, 1.07). The sera were analyzed for HbA(1c), fasting blood glucose (FBG), total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL) and low-density lipoprotein cholesterol (LDL). The levels of HbA(1c) did not differ significantly between males (8.33 +/- 0.06%) and females (8.47 +/- 0.07%), whereas female patients had significantly higher FBG (10.01 +/- 0.13 mmol/l) than males (9.31 +/- 0.11 mmol/l). HbA(1c) showed direct and significant correlations with cholesterol, triglycerides and LDL and inverse correlation with HDL. Female diabetic patients had significantly higher levels of serum cholesterol (5.42 +/- 0.03 vs. 5.18 +/- 0.03 mmol/l) and HDL (1.32 +/- 0.01 vs. 1.12 +/- 0.01 mmol/l) as compared to males. There was no significant difference in triglycerides and LDL between the two genders. Older patients (>70 years) had significantly lower FBG, cholesterol, triglycerides and LDL. There was a linear and significant increase in triglycerides in the patients of both genders with impaired glycemic control. Both male and female patients with worse glycemic control (HbA(1c) > 9%) had significantly high cholesterol and LDL levels. Serum HDL showed a significant and inverse relationship with uncontrolled hyperglycemia in females but not in males. These findings clearly suggest that HbA(1c) can provide valuable supplementary information about the extent of circulating lipids besides its primary role in monitoring long-term glycemic control. Further studies are warranted to reinforce the potential of HbA(1c) as a biomarker for screening of high-risk diabetic patients.