By Louis Kuritzky, MD, Clinical Assistant Professor, University of Florida, Gainesville, and Associate Editor, Internal Medicine Alert.
Risk Factors and Diabetic Neuropathy
Although we have recently enjoyed the FDA approval of two agents for treatment of diabetic peripheral neuropathic pain (duloxetine [Cymbalta], pregabalin [Lyrica]), as yet we have no treatment for diabetic peripheral neuropathy (DPN) itself. Trials in both type 1 and type 2 diabetes have shown that tight glycemic control reduces the incidence of DPN; additionally, tight blood pressure control has been shown to reduce the incidence of DPN in type 2 DM. Identification of potentially modifiable risk factors for development of DPN might aid clinicians in its prevention.
Studying subjects from the European Diabetes Prospective Complications Study (n = 3250), Chaturvedi and colleagues identified 276 cases of new onset neuropathy during an observation period of approximately 10 years. Multivariate analysis indicated that the greatest odds ratios for development of DNP were seen with duration of diabetes, A1C, BMI, and smoking.
Good glucose control is already a target to reduce incident DPN. When controlling for A1C and duration of diabetes, other prominent risk factors emerged. For instance elevated levels of LDL showed a 22-26% increase in odds ratio for DPN. Ultimately, the 2 factors with greatest increase in odds ratio for development of DPN were cardiovascular disease at the time of enrollment (ie, at baseline), in which case the odds ratio was almost triple, and microalbuminuria, which was associated with greater than a 2-fold increase.
Chaturvedi N, et al. N Eng J Med. 2005;352:341-350.
Stress Reduction in African Americans Treated for HBP
Cardiovascular disease remains the number one cause of mortality in America. The African American population shoulders a disproportionate burden of this mortality, likely due to a correspondingly increased incidence, severity, and prevalence of hypertension, and a greater degree of manifest target organ damage.
A diversity of available antihypertensive agents notwithstanding, only a fraction of hypertensive patients have reached and maintain currently identified blood pressure goals. Lifestyle modification may provide substantial reductions in blood pressure, but clinicians may commonly include only diet, exercise, and salt modulation as typical components. Schneider and colleagues evaluated whether stress reduction through Transcendental Medication might result in meaningful impact upon BP in African American men.
Study subjects (n = 150) were randomized to either Transcendental Meditation (TM) 20 minutes twice daily, progressive muscle relaxation, or health education classes, and were followed for 12 months. Compared to health education classes, the TM group enjoyed a significant reduction in antihypertensive medication. Although SBP did not differ significantly between treatment groups, diastolic BP was 2.7 mm Hg lower in the TM group. Looking just at the female subjects, TM impact was much more substantial, resulting in a BP change of 7.3/-6.9 vs -0.7/-3.0 BP change in subjects allocated to education classes. Transcendental Meditation is a specific meditation technique requiring specific, personal instruction. Whether other relaxation or meditation techniques might also be efficacious is unknown.
Schneider RH, et al. Am J Hypertens. 2005;18:88-98.
Folate Intake and the Risk of Hypertension
There are several ways in which folate could play a vital role in the maintenance of vascular health. Folate treatment lowers homocysteine, an acknowledged cardiovascular risk factor. Folate supplementation has also been shown to lower blood pressure and improve endothelial cell function on a short-term basis. Whether long-term dietary and supplemental intake of folate is ultimately related to development of hypertension (HTN) has not been studied.
The Nurses Health Study I and Nurses Health Study II comprise more than 150,000 individuals who have been studied observationally since the early 1990s; they are considered separate studies because the former comprises younger women (age, 27-44 at enrollment vs age 43-70). Amongst this population, during the observation period 7,373 persons developed new-onset HTN.
In younger women, those who consumed 1 mg or more of folate daily enjoyed half the relative risk of developing HTN compared to women who consumed 0.2 mg or less. In older women, the results were similarly favorable, but less dramatic (RR =0.82).
The evidence base linking folate intake with vascular health is plausible. These observational data strengthen the association between folate nutriture and maintenance of normotension.
Forman JP, et al. JAMA. 2005;293: 320-329.