Management of hyperhomocysteinemia

Homocysteine, an additional factor, is linked to osteoporosis in postmenopausal women with type 2 diabetes

We explored the relationship between plasma total homocysteine concentration and osteoporosis in postmenopausal patients with type 2 diabetes. Postmenopausal patients with type 2 diabetes (n = 258) were enrolled in a cross-sectional hospital-based study. Osteoporosis was documented by dual energy X-ray absorptiometry. Plasma total homocysteine concentration was measured using fluorescence polarization immunoassay. Risk factors for osteoporosis and determinants of homocysteine were obtained from blood samples and interviewer questionnaire. We found that plasma total homocysteine levels were higher in subjects with osteoporosis and diabetes than without [(9.5 ± 2.0) vs. (10.4 ± 2.4) μmol/l, p = 0.001]. The association of homocysteine with osteoporosis was independent of possible risk factors for osteoporosis in diabetes (e.g., duration of diabetes, HbA1c, body mass index, serum 25-hydroxyvitamin D, thiazolidinediones, and retinopathy) and determinants of homocysteine concentration (age, serum folate and vitamin B12, renal status, and biguanide use) [OR 1.40 (1.02-1.90), p = 0.036]. In addition, bone mineral density was closely correlated with homocysteine as a continuous variable after adjusting for age [r = -0.64 (-0.69 to -0.58), p = 0.002]. Furthermore, per increase of 5.0 μmol/l, plasma homocysteine was related to osteoporosis, after controlling for per unit increase of other factors [OR 1.42 (1.07-1.96), p = 0.027]. The optimal cut-off point for the plasma homocysteine level distinguishing diabetic patients with osteoporosis from without was 10.18 μmol/l. The results suggest that plasma total homocysteine concentration is independently associated with the occurrence of osteoporosis in postmenopausal patients with type 2 diabetes. Future prospective studies are warranted to clarify the relationship.

Homocysteine is linked to macular edema in type 2 diabetes

AIM

To explore the relationship between plasma total homocysteine concentration and diabetic macular edema in patients with type 2 diabetes.

METHODS

Patients with type 2 diabetes (n = 176) were enrolled in a cross-sectional hospital-based study. Diabetic macular edema status was documented by fundus photographs. Plasma total homocysteine concentration was measured using fluorescence polarization immunoassay. Normal control plasma homocysteine was established in 115 healthy subjects. Risk factors for diabetic macular edema were obtained from fasting blood samples and interviewer questionnaire.

RESULTS

Diabetic patients had increased plasma homocysteine compared with normal control. Plasma homocysteine levels were higher in subjects with diabetic macular edema than without ((11.4 ± 2.7) versus (8.5 ± 1.9) (μmol/l), p = 0.000). The association of homocysteine with diabetic macular edema was independent of major risk factors for diabetic macular edema (duration of diabetes, HbA1c, lipid) and determinants of higher homocysteine concentration (age, gender, serum folate and vitamin B12, renal status, and biguanide use) (OR: 1.63 (1.02-2.14), p = 0.018). Furthermore, per increase of 5.0 μmol/l plasma homocysteine was related to macular edema, after controlling for per unit increase of other factors (OR: 1.64 (1.04-2.16), p = 0.019).

CONCLUSIONS

Plasma total homocysteine concentration is independently associated with the occurrence of macular edema in type 2 diabetes. Future prospective studies are warranted to clarify the relationship.

Homocysteine and reactive oxygen species in metabolic syndrome, type 2 diabetes mellitus, and atheroscleropathy: the pleiotropic effects of folate supplementation

Homocysteine has emerged as a novel independent marker of risk for the development of cardiovascular disease over the past three decades. Additionally, there is a graded mortality risk associated with an elevated fasting plasma total homocysteine (tHcy). Metabolic syndrome (MS) and type 2 diabetes mellitus (T2DM) are now considered to be a strong coronary heart disease (CHD) risk enhancer and a CHD risk equivalent respectively. Hyperhomocysteinemia (HHcy) in patients with MS and T2DM would be expected to share a similar prevalence to the general population of five to seven percent and of even greater importance is: Declining glomerular filtration and overt diabetic nephropathy is a major determinant of tHcy elevation in MS and T2DM.

There are multiple metabolic toxicities resulting in an excess of reactive oxygen species associated with MS, T2DM, and the accelerated atherosclerosis (atheroscleropathy). HHcy is associated with an increased risk of cardiovascular disease, and its individual role and how it interacts with the other multiple toxicities are presented.

The water-soluble B vitamins (especially folate and cobalamin-vitamin B₁₂) have been shown to lower HHcy. The absence of the cystathionine beta synthase enzyme in human vascular cells contributes to the importance of a dual role of folic acid in lowering tHcy through remethylation, as well as, its action of being an electron and hydrogen donor to the essential cofactor tetrahydrobiopterin. This folate shuttle facilitates the important recoupling of the uncoupled endothelial nitric oxide synthase enzyme reaction and may restore the synthesis of the omnipotent endothelial nitric oxide to the vasculature.