Complications of diabetes mellitus - Management
Modulating and ameliorating diabetic complications may in turn improve the overall quality of life for diabetic patients. For example; when elevated blood pressure was tightly controlled, diabetic related deaths were reduced by 32% compared to those with less controlled blood pressure. Many observational and clinical studies had been conducted to investigate the role of several vitamins on diabetic complications, the results of these studies elevated a suggested beneficial role of vitamins on diabetic complications.
In the First National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study, vitamin supplementations were observed to be associated with 24% reduction on the risk of diabetes was observed during 20 years of follow-up. Many observational studies and clinical trials have linked several vitamins with the pathological process of diabetes; these vitamin include folate, thiamine, β-carotene, and vitamin E, C, B 12, and D.
However, numerous researches had been shown inconsistent results about the roles of vitamins on diabetic risk and complications. Most of these researches performed to investigate effect of individual vitamin without looking to status of other vitamins. Even though, it is expected that vitamin supplementation might be more effective and might induce a beneficial role on diabetic process when deficiency exists.
Despite the current contradictory in the association between the discussed vitamins and diabetic complications, and regardless of the lack of strong and inclusive evidence about their mechanism of action, the discussed effects of these vitamins seem promising for preventing and reducing the severity of diabetic complications. Since optimal blood level of all vitamins is important for normal metabolic process, it is essential to encourage diabetic patients and high risk population to try to achieve and maintain this level. And until more inclusive evidence is established about vitamins supplementations, the awareness of diabetic patients should be elevated toward the importance of consuming adequate amounts of all vitamins.
Thiamine: Thiamine acts as an essential cofactor in glucose metabolism, therefore, it may modulate diabetic complications by controlling glycemic status in diabetic patients. Additionally, deficiency of thiamine was observed to be associated with dysfunction of β-cells and impaired glucose tolerance. Different studies indicated possible role of thiamin supplementation on the prevention or reversal of early stage diabetic nephropathy, as well as significant improvement on lipid profile.
vitamin B12: Low serum B12 level is common finding in diabetic patients especially those taking Metformin or advanced age patients. Vitamin B12 deficiency has been linked to two diabetic complications; atherosclerosis and diabetic neuropathy.
Folic acid: Low plasma concentrations of folic acid were found to be associated with high plasma homocysteine concentrations. In clinical trials, homocysteine concentrations were effectively reduced within 4 to 6 weeks of oral supplementation of folic acid. Moreover, since the activity of endothelial NO synthase enzyme might be potentially elevated by folate, folate supplementation might be capable of restoring the availability of NO in endothelium, therefore, improving endothelial function and reducing the risk for atherosclerosis. van Etten et al., found that a single dose of folic acid might help in reducing the risk of vascular complications and enhancing endothelial function in adults with type 2 diabetes by improving nitric oxide status.
Antioxidants: Three vitamins, ascorbic acid; α-tocopherol; and β-carotene, are well recognized for their antioxidant activities in human. Free radical-scavenging ability of antioxidants may reduce the oxidative stress and thus may protect against oxidative damage. Based on observational studies among healthy individuals, antioxidant concentrations were found to be inversely correlated with several biomarkers of insulin resistance or glucose intolerance. Antioxidants may induce beneficial effects on diabetic complications by reducing blood pressure, attenuating oxidative stress and inflammatory biomarkers, improving lipid metabolism and insulin-mediated glucose disposal, as well as by enhancing endothelial function. In addition to its antioxidant capacity, vitamin C has been proposed to induce beneficial effects on diabetes by two other mechanisms. Firstly; vitamin C may replace the glucose in many chemical reactions due to their similarity in structure, thus, it may prevent the non-enzymatic glycosylation of proteins, and therefore it might reduce glycated hemoglobin (HbA1c) levels. Secondly, vitamin C has also been suggested to play an important role in lipid regulation as a controller of catabolism of cholesterol to bile acid.
Vitamin D: The insufficiency of vitamin D is a common finding in diabetic patients. Observational studies showed that serum vitamin D is inversely associated with biomarkers of diabetes; impaired insulin secretion, insulin resistance, and glucose intolerance. It has been suggested that vitamin D may induce a beneficial effects on diabetic complications by several mechanisms. Firstly; it could modulate differentiation and growth of pancreatic β-cells and it may also protect these cells from apoptosis, thus improving β-cells functions and survival.
Vitamin D has also been suggested to act on immune system and modulate inflammatory responses by influencing proliferation and differentiation of different immune cells. Moreover, deficiency of vitamin D may contribute to diabetic complications by inducing hyperparathyroidism, since elevated parathyroid hormone levels are associated with reduced β-cells function, impaired insulin sensitivity, and glucose intolerance. Finally, vitamin D may reduce the risk of vascular complications by modulating lipid profile
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