Glycated haemoglobin, diabetes, and mortality in men in Norfolk cohort of european prospective investigation of cancer and nutrition (EPIC-Norfolk)

Management of intermittent claudication: the importance of secondary prevention

Atherosclerotic peripheral arterial disease (PAD) is a common disorder usually associated with silent or symptomatic arterial disease elsewhere in the circulation and a cluster of cardiovascular risk factors inducing atheroma progression and/or thrombotic complications. Because of these strong clinical associations, especially with coronary heart disease, the ankle-brachial pressure index (ABPI) is of prognostic significance. The clinical management of IC should include relief of symptoms combined with prevention of secondary cardiovascular complications, e.g. acute thrombotic events causing limb- or life-threatening ischaemia, which are often due to atherosclerotic plaque rupture leading to thrombotic vessel occlusion. Many patients with PAD do not receive an optimum package of secondary prevention, tailored to include maximum cholesterol reduction, BP and glycaemic control, ACE inhibition and single or combination anti-platelet therapy. This review considers recent information from large secondary prevention trials, e.g. the PAD subgroups within the HOPE, CAPRIE and statin studies. Slowing progression of atherosclerosis, and inducing stabilisation and regression of atheromatous plaques, is now feasible using long-term combination drug therapy. The phrase angle quotation mark, leftangle quotation mark, leftconservative therapyangle quotation mark, rightangle quotation mark, right, popular among vascular surgeons, implies a passive minimal-intervention strategy of surveillance and lifestyle advice; such terminology is perhaps no longer appropriate since considerable improvements in survival are likely to accrue if all patients with PAD, especially those with low ABPI, receive vigorous, titrated medical therapies, tailored to individual patients, as part of an evidence-based secondary prevention regime.

Glucose metabolism in renal transplant recipients on tacrolimus: the effect of steroid withdrawal and tacrolimus trough level reduction

The relative role of steroids and tacrolimus in the development of glucose metabolic disorders and hyperlipidemia after renal transplantation has not yet been clearly established. Therefore, glucose metabolism was prospectively evaluated by intravenous glucose tolerance test, as was lipid profile, in fifteen white nondiabetic renal transplant recipients three times: before and after steroid withdrawal and after tacrolimus trough level reduction. After withdrawal of 10 mg of prednisolone, insulin resistance decreased (fasting C-peptide, 0.99 to 0.77 nmol/L [P < 0.0009]; fasting insulin, 9.5 to 8.1 mU/L [P = 0.09]; insulin/glucose ratio, 1.85 to 1.45 mU/mmol [P = 0.10]) and lipid levels decreased (total cholesterol, 5.1 to 4.2 mmol/L [P = 0.006]); HDL cholesterol, 1.4 to 1.1 mmol/L [P = 0.01]; LDL cholesterol, 3.0 to 2.5 mmol/L [P = 0.15]; triglycerides, 1.52 to 0.91 mmol/L [P = 0.02]). After tacrolimus trough level reduction from 9.5 to 6.4 ng/ml, pancreatic beta-cell secretion capacity improved (C-peptide secretion increased from 49.0 to 66.6 nmol x min/L [P = 0.04] and insulin secretion increased from 1134 to 1403 mU x min/L [P = 0.06]). HbA1c improved also, from 5.9 to 5.3% (P = 0.002). Lipids did not change. In conclusion, steroid withdrawal resulted in a decrease in insulin resistance and a reduction in lipids, and tacrolimus trough level reduction resulted in an improved pancreatic beta-cell secretion capacity. Therefore, these therapeutic measurements may contribute to the reduction of the cardiovascular morbidity and mortality in renal transplant recipients.

Strong in body and spirit: lifestyle intervention for Native American adults with diabetes in New Mexico

OBJECTIVE

To determine the effects of a culturally appropriate diabetes lifestyle intervention for Native Americans on risk factors for complications of diabetes.

RESEARCH DESIGN AND METHODS

A nonrandomized, community-based diabetes intervention trial was conducted in three Native American sites in New Mexico from 1993-1997. Participants were assigned to intervention or control based on community of residence. Intervention sessions were held approximately 6 weeks apart over approximately 10 months. The intervention was delivered in site A in family and friends (FF) groups (n = 32); site B received the same intervention in one-on-one (OO) appointments (n = 39); and site C received usual medical care (UC) (n = 33) (total participants, n = 104). Primary change in HbA(1c) level was assessed at 1 year.

RESULTS

Adjusted mean change in HbA(1c) value varied significantly across the three arms at 1 year (P = 0.05). The UC arm showed a statistically significant increase in adjusted mean HbA(1c) change (1.2%, P = 0.001), whereas both intervention arms showed a small nonsignificant (P > 0.05) increase in the adjusted mean change (0.5% and 0.2% for FF and OO arms, respectively). The increase was statistically significantly smaller in the combined intervention arms (0.4%) compared with the UC arm (1.2%, P = 0.02).

CONCLUSIONS

Lifestyle intervention has the potential to substantially reduce microvascular complications, mortality, and health care utilization and costs if the change is sustained over time.

Hypoglycemia-associated autonomic failure in diabetes

Hypoglycemia is the limiting factor in the glycemic management of diabetes. The concept of hypoglycemia-associated autonomic failure (HAAF) in diabetes posits that recent antecedent iatrogenic hypoglycemia causes both defective glucose counterregulation (by reducing the epinephrine response to falling glucose levels in the setting of an absent glucagon response) and hypoglycemia unawareness (by reducing the autonomic and the resulting neurogenic symptom responses) and thus a vicious cycle of recurrent hypoglycemia. Perhaps the most compelling support for HAAF is the finding that as little as 2-3 wk of scrupulous avoidance of hypoglycemia reverses hypoglycemia unawareness and improves the reduced epinephrine component of defective glucose counterregulation in most affected individuals. Insight into this pathophysiology has led to a broader view of the clinical risk factors for hypoglycemia to include indexes of compromised glucose counterregulation and provided a framework for the study of the mechanisms of iatrogenic hypoglycemia and, ultimately, its elimination from the lives of people with diabetes.

Effect of two antihypertensive combinations on metabolic control in type-2 diabetic hypertensive patients with albuminuria: a randomised, double-blind study

The objective of this study was to compare, at equal blood pressure (BP) reduction, the effect of two different combinations on metabolic control and albuminuria in type 2 diabetic hypertensive patients with albuminuria. This was a prospective, randomised, double-blind, parallel, controlled trial carried out in 11 Spanish hospitals. A total of 103 type 2 diabetic patients with stable albuminuria and BP not controlled on monotherapy were randomised of which 93 finished the study. After a 4-week single-blind placebo period, patients were randomised to verapamil SR/trandolapril 180/2 mg (VT) or to enalapril/hydroclorothiazide 20/12.5 mg (EH). Treatment duration was 6 months. The main outcome measures were changes in BP, 24-h albuminuria, blood glucose and glycated haemoglobin. Overall BP was significantly reduced from 157.3 +/- 12.0/98.3 +/- 6.4 mm Hg to 140.5 +/- 14.5/86.1 +/- 8.2 mm Hg (P < 0.001) and albuminuria significantly decreased from 508.6 +/- 693.8 mg/24 h to 253.4 +/- 517.2 mg/24 h (P < 0.001), both without significant differences between treatments. Glycated haemoglobin was not modified on VT: baseline, 5.91 +/- 1.43%; end of treatment, 5.94 +/- 1.62%, but increased on EH: baseline, 5.96 +/- 1.25%; final, 6.41 +/- 1.51%, (ANOVA interaction P = 0.040). At the end of the study, a blood glucose <126 mg/dL was attained in 72.7% of the VT group-improving in 29.5% and worsening in 6.8% of patients (P = 0.021)-and in 50% of the EH group, 13.6% of patients improved and 11.4% worsened (P = 1.000). There were no changes in body weight, serum creatinine, uric acid, potassium, cholesterol, tryglicerides and serum albumin. In hypertensive type 2 diabetic patients not controlled on monotherapy, both treatments similarly reduced albuminuria. The combination verapamil/ trandolapril seems to allow a better metabolic control than enalapril/hydroclorothiazide.

Fat consumption and HbA(1c) levels: the EPIC-Norfolk study

OBJECTIVE

To describe the relationship between total dietary fat and the pattern of fat intake and HbA(1c).

RESEARCH DESIGN AND METHODS

In this cross-sectional study, 2,759 men and 3,464 women (40-78 years of age) without a previous diagnosis of type 2 diabetes were recruited from a population-based sampling frame. Diet was assessed using a self-reported semiquantitative food frequency questionnaire.

RESULTS

The HbA(1c) level was negatively associated with the polyunsaturated fat-to-saturated fat ratio (P:S ratio) of the diet (beta = -0.0338 HbA(1c)% per SD change in P:S ratio; P < 0.001) and positively associated with the total level of fat intake (beta = 0.0620 HbA(1c)% per SD change in total fat intake; P < 0.001), adjusted for age and total energy intake. The associations remained significant when adjusted for each other and for total energy, protein, age, sex, family history of diabetes, BMI, waist-to-hip ratio, physical activity, and smoking (for P:S ratio, beta = -0.0200 HbA(1c)% per SD change in P:S ratio, P = 0.013; for total fat, beta = 0.420% HbA(1c)% per SD change in total fat intake, P < 0.001). The benefits from a high P:S ratio were attributed to a lower saturated fat intake.

CONCLUSIONS

These findings demonstrate independent associations between HbA(1c) concentration across the normal range of HbA(1c) and both total fat intake and the pattern of dietary fat intake. They provide further support to efforts promoting modifications in the intake of dietary fat.

Early recognition and treatment of glucose abnormalities to prevent type 2 diabetes mellitus and coronary heart disease

Striking parallels exist in both risk and protective factors between coronary heart disease and type 2 diabetes mellitus. Patients with insulin resistance are more likely to develop diabetes and coronary heart disease. Better treatment of diabetes may result in less coronary heart disease, although this has not yet been established. Reliance on fasting glucose determinations alone will overlook a substantial number of patients at risk for diabetes and subsequent coronary heart disease. Measurement of glycosylated hemoglobin should be a routine part of screening for patients at risk for diabetes. Patients with glycosylated hemoglobin levels in the high-normal range should be treated more aggressively with diet, exercise, and medication because evidence is good that diabetes can be prevented (or its onset delayed). Patients with borderline elevations of low-density lipoprotein cholesterol concentrations and with high-normal glycosylated hemoglobin levels should be considered for statin therapy, and patients with hypertension with high-normal glycosylated hemoglobin levels should be treated with angiotensin-converting enzyme inhibitors as first-line agents. Studies to determine whether metformin is useful in this population are ongoing.

Drugs for cardiovascular risk reduction in the diabetic patient

The diabetic patient is at increased risk for cardiac events. Lowering hemoglobin A1c levels even within the normal range is associated with less cardiac risk. Oral agents for diabetes that reduce insulin resistance and its associated cardiac risk factors in addition to lowering glucose should be used. Energetic reduction of blood pressure with an emphasis on the use of angiotensin-converting enzyme inhibitors and beta blockers will further reduce cardiac risk. Reduction of low-density lipoprotein and triglyceride levels and elevation of high-density lipoprotein levels through judicious use of statins and other anti-lipid agents is essential and will lower the rate of cardiac events in the diabetic patients even more than in the nondiabetic patients. In addition, aspirin and folic acid supplementation should be utilized. Use of a multiple risk factor management strategy with these drugs will lower morbidity and mortality, improve quality of life, and save cost for the diabetic patient.

Dietary carbohydrates, physical inactivity, obesity, and the 'metabolic syndrome' as predictors of coronary heart disease

Several decades of epidemiological and clinical research have identified physical inactivity, excessive calorie consumption, and excess weight as common risk factors for both type 2 diabetes mellitus and coronary heart disease. This trio forms the environmental substrate for a now well-recognized metabolic phenotype called the insulin resistance syndrome. Recent data suggest that a high intake of rapidly absorbed carbohydrates, which is characterized by a high glycemic load (a measure of carbohydrate quality and quantity), may increase the risk of coronary heart disease by aggravating glucose intolerance and dyslipidemia. These data also suggest that individuals who are obese and insulin resistant are particularly prone to the adverse effects of a high dietary glycemic load. In addition, data continue to accumulate suggesting the important beneficial effects of physical activity, even at moderate levels, and weight reduction on improving insulin sensitivity and reducing the risk of coronary heart disease. Future metabolic studies should continue to quantify the physiological impact of different foods on serum glucose and insulin, and such information should routinely be incorporated into large-scale and long-term prospective studies, in which the possible interaction effects between diet and other metabolic determinants such as physical activity and obesity can be examined. Until more definitive data are available, replacing refined grain products and potatoes with minimally processed plant-based foods such as whole grains, fruits, and vegetables, and reducing the intake of high glycemic load beverages may offer a simple strategy for reducing the incidence of coronary heart disease.

Diabetes mellitus and diabetes-associated vascular disease

Diabetes-related cardiovascular disease remains the leading cause of death in patients with type 2 diabetes. Hypertension is common among diabetics and has the same pathogenetic mechanisms as insulin resistance, in which the activated renin-angiotensin system contributes to the emerging high blood pressure and hyperglycemia. Hyperglycemia is one of the triggering factors for vascular dysfunction and clotting abnormalities and, therefore, for accelerated atherosclerosis in diabetes. Glycated hemoglobin levels, as a reflection of the degree of glycemia, are strongly associated with the risk of cardiovascular disease in diabetics and in the general population. Tight glycemic control, the treatment of dyslipidemia and raised blood pressure, in addition to the use of antiplatelet therapy, all powerfully reduce the risks associated with diabetes. Furthermore, angiotensin-converting enzyme inhibitors might offer additional cardioprotection to diabetics above that provided by blood pressure reduction.

PPARalpha deficiency reduces insulin resistance and atherosclerosis in apoE-null mice

PPARalpha is a ligand-dependent transcription factor expressed at high levels in the liver. Its activation by the drug gemfibrozil reduces clinical events in humans with established atherosclerosis, but the underlying mechanisms are incompletely defined. To clarify the role of PPARalpha in vascular disease, we crossed PPARalpha-null mice with apoE-null mice to determine if the genetic absence of PPARalpha affects vascular disease in a robust atherosclerosis model. On a high-fat diet, concentrations of atherogenic lipoproteins were higher in PPARalpha(-/-)apoE(-/-) than in PPARalpha(+/+)apoE(-/-) mice, due to increased VLDL production. However, en face atherosclerotic lesion areas at the aortic arch, thoracic aorta, and abdominal aorta were less in PPARalpha-null animals of both sexes after 6 and 10 weeks of high-fat feeding. Despite gaining as much or more weight than their PPARalpha(+/+)apoE(-/-) littermates, PPARalpha(-/-)apoE(-/-) mice had lower fasting levels of glucose and insulin. PPARalpha-null animals had greater suppression of endogenous glucose production in hyperinsulinemic clamp experiments, reflecting less insulin resistance in the absence of PPARalpha. PPARalpha(-/-)apoE(-/-) mice also had lower blood pressures than their PPARalpha(+/+)apoE(-/-) littermates after high-fat feeding. These results suggest that PPARalpha may participate in the pathogenesis of diet-induced insulin resistance and atherosclerosis.