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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A significantly lower vitamin C concentration has been found in the blood and particularly in the leukocytes of hypercholesterolemic diabetic patients than of healthy blood donors. Ascorbic acid administered in a dose of 500 mg per day for 12 months to metabolically stabilized hypercholesterolemic subjects with maturity-onset diabetes mellitus (diabetic diet without insulin or diabetic drugs) brought about a striking decline of cholesterolemia and a moderate decline of triglyceridemia. The serum lipid level in the control group given placebo remained unaltered. A daily administration of 500 mg of ascorbic acid for six months failed to affect the fasting level of serum immunoreactive insulin. It is assumed that the long-term administration of ascorbic acid to maturity-onset diabetics removed the tissue ascorbate deficiency and improved the liver ability to compensate the increased endogenous synthesis of cholesterol by its enhanced transformation to bile acids.
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PMID:Hypocholesterolemic effect of ascorbic acid in maturity-onset diabetes mellitus. 36 79

References and texts in the fields of diabetes and clinical chemistry commonly report that ascorbic acid when given orally or parenterally gives a false-positive reaction to the copper reduction glucose test (Clinitest). This impression is based on a study in which ascorbic acid (250 mg./dl.) was added to urine in vitro, with a resultant positive-test reading in the absence of glucose. Ascorbic acid is a reducing agent, and theoretically it could interfere with the copper reduction method of glucose detection. In the current study 10 nondiabetic men were ingesting 4 and 6 gm. ascorbic acid per day. A total of 360 glucose detection tests with the copper reduction method were undertaken. In no instance was there a positive reaction to the glucose test.
Diabetes Care
PMID:Noneffect of oral urinary copper ascorbic acid on reduction glucose test. 55 83

This review presents a Total Environment evaluation of current inorganic fluoride intake by human populations. Inorganic fluoride is a persistant bioaccumulator, and the ever-increasing use (and release) of fluoride compounds in the environment should be of long-term concern in population sub-groups who are most susceptible, and therefore, most "at risk". One of these sub-groups consists of people with impaired kidney function, including subjects with nephorphatic diabetes. The diabetes factor is of particular relevance, not only because the incidence of diabetes has increased by 6%/yr during the period 1965-1975, but also because subjects with nephropathic diabetes can exhibit a polydipsia-polyurea syndrome that results in increased intake of fluoride, along with greater-than-normal retention of a given fluoride dosage. People with inadequate dietary intakes (particularly of Ca and/or Vitamin C) are also likely to be more "at risk" as a consequence of low-dose long-term fluoride ingestion. Evidence is presented, showing that there has been an escalation in dialy fluoride intake via the total human food-and-beverage chain, with the likelihood that this escalation will continue in the future. Recent observations, relating to an increasing incidence of chronic fluoride intoxication among humans, is also emphasized.
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PMID:Some current aspects of environmental fluoride. 91 53

Xerostomia, the subjective feeling of dry mouth, affects millions of people particularly the elderly. It is invariably associated with hypofunction of the salivary glands. The amount, rate of secretion, and composition of saliva are regulated by both sympathetic and parasympathetic receptor systems whose stimulation transmits signals through intracellular messengers (cations, nucleotides, phospholipid derivatives) to structures and enzymes within the cell. Salivary glands express a variety of cell-surface receptors including adrenergic (alpha and beta), muscarinic-cholinergic, substance P, vasoactive intestinal peptide hormone, and ATP receptors. Ascorbate which is present in salivary acinar cells in relatively high concentrations, is closely involved in many cellular functions including the metabolism of pyrimidines, intracellular calcium, the catecholamines and other neurotransmitters which regulate salivary gland exocytosis. Ascorbate-dependent carboxyl-terminal peptide alpha-amidation enzyme similar to the pituitary peptidyl-glycine alpha-amidating monooxygase, is also present in salivary glands. It is therefore not fortuitous that the seemingly unrelated numerous factors like aging, drug ingestion, pregnancy, smoking, ionizing radiation, stress, and various pathological states such as cancer, autoimmune disorders, diabetes mellitus, and hypertension often implicated in the causation of xerostomia, all promote increased tissue requirement for and/or depletion of ascorbate.
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PMID:Ascorbate status and xerostomia. 143 93

Free radical mechanisms are increasingly being implicated in the pathogenesis of tissue damage in diabetes. Various sources of free radicals may modulate oxidative stress in diabetes, including non-enzymatic glycosylation of proteins and monosaccharide autooxidation, polyol pathway activity, indirect production of free radicals through cell damage from other causes, and reduced antioxidant reserve. Ascorbic acid, which may be a principal modulator of free radical activity in diabetes, is shown to be consumed, presumably through free radical scavenging, thus preserving levels of other antioxidants such as glutathione.
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PMID:Modulators of free radical activity in diabetes mellitus: role of ascorbic acid. 145 May 96

Effects of glucose and ascorbic acid on in vitro collagen and DNA synthesis were evaluated in human umbilical vein endothelial cells. Ascorbic acid significantly potentiated collagen synthesis. Incubation of cells with elevated glucose concentration for 24h significantly reduced [3H]-thymidine uptake (2h). However, the addition of ascorbic acid (0.1 mM) dramatically prevented the inhibition of thymidine uptake. Based on these data, it is suggested that ascorbic acid supplementation in diabetics may prevent or ameliorate diabetic angiopathy.
Diabetes Res 1991 Oct
PMID:Ascorbic acid prevents the inhibition of DNA synthesis induced by high glucose concentration in cultured human endothelial cells. 184 14

Abnormalities of ascorbic acid metabolism have been reported in experimentally-induced diabetes and in diabetic patients. Ascorbate is a powerful antioxidant, a cofactor in collagen biosynthesis, and affects platelet activation, prostaglandin synthesis and the polyol pathway. This suggests a possible close interrelationship between ascorbic acid metabolism and pathways known to be influenced by diabetes. We determined serum ascorbic acid and its metabolite, dehydroascorbic acid, as indices of antioxidant status, and the ratio, dehydroascorbate/ascorbate, as an index of oxidative stress, in 20 matched diabetic patients with and 20 without microangiopathy and in 22 age-matched control subjects. Each study subject then took ascorbic acid, 1 g daily orally, for six weeks with repeat measurements taken at three and six weeks. At baseline, patients with microangiopathy had lower ascorbic acid concentrations than those without microangiopathy and control subjects (42.1 +/- 19.3 vs 55.6 +/- 20.0, p less than 0.01, vs 82.9 +/- 30.9 mumol/l, p less than 0.001) and elevated dehydroascorbate/ascorbate ratios (0.87 +/- 0.46 vs 0.61 +/- 0.26, p less than 0.01, vs 0.38 +/- 0.14, p less than 0.001). At three weeks, ascorbate concentrations rose in all groups (p less than 0.0001) and was maintained in control subjects (151.5 +/- 56.3 mumol/l), but fell in both diabetic groups by six weeks (p less than 0.01). Dehydroascorbate/ascorbate ratios fell in all groups at three weeks (p less than 0.0001) but rose again in the diabetic groups by six weeks (p less than 0.001) and was unchanged in the control subjects. Dehydroascorbate concentrations rose significantly from baseline in all groups by six weeks of ascorbic acid supplementation (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Disturbed handling of ascorbic acid in diabetic patients with and without microangiopathy during high dose ascorbate supplementation. 188 88

Ascorbic acid (AA), dehydroascorbic acid (DHAA), and vitamin E were measured in tissues and plasma of 30 control and 30 spontaneously diabetic BioBreeding rats (BBdp) during development and before the onset of diabetes. At weaning, rats were fed an AIN-76 semisynthetic diet for 30, 64, or 113 days, after which plasma and tissues from 10 rats of each group were collected and analysed for AA, DHAA, and vitamin E. AA and DHAA levels were significantly increased in plasma and spleen of the diabetes-prone rats compared with those of the control group at 30 and 64 days, but the difference disappeared by 113 days. No differences were observed in liver, adrenals, thymus, and pancreas at any of the time periods. However, lower levels of vitamin E were observed in adrenal gland, thymus, and pancreas of the diabetes-prone rats. It is concluded that BBdp rats have an altered metabolism of AA, DHAA, and vitamin E, before the onset of diabetes. These changes could be due to genetic and physiological factors operating during development of this rat strain.
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PMID:Vitamin C and vitamin E status in the spontaneously diabetic BB rat before the onset of diabetes. 198 74

Collagen and proteoglycans are two major constituents of the extracellular matrix, and their abnormalities have been incriminated in the pathogenesis of diabetic complications. A decrease of plasma ascorbic acid has been reported in diabetes and thus may play a role in the collagen and proteoglycan abnormalities in diabetes. Ascorbic acid and glucose share structural similarity, and their metabolism may interact at the level of membrane transport and cellular action. In this study, we used a fibroblast culture system to explore this possibility. Ascorbic acid increased collagen and proteoglycan both in the culture medium and the cell layer. This stimulatory action of ascorbic acid was inhibited by the presence of glucose at a concentration of 25 mM. The effect of high glucose concentration was not mediated by inhibition of ascorbic acid uptake by fibroblasts. Insulin is able to abolish this inhibitory action of glucose on collagen production, but the precise mechanism is unclear. These results show that the high glucose concentration in diabetes can impair the action of ascorbic acid at the cellular level. This may further accentuate the problem of decreased availability of this vitamin as a result of its low plasma concentration.
Diabetes 1991 Mar
PMID:Interaction of ascorbic acid and glucose on production of collagen and proteoglycan by fibroblasts. 199 79

Ascorbic acid is required in the synthesis of collagen and is also an important anti-oxidant. In a previous study, plasma ascorbic acid concentration was found to be decreased in diabetic patients but there was no relationship with blood glucose level. In the current study of diabetic patients, both plasma ascorbic acid and its urinary excretion correlated inversely with glycosylated hemoglobin level. Plasma ascorbic acid was also lower in diabetic rats but urinary ascorbic acid was elevated. The divergent trend in urinary ascorbic acid excretion observed in diabetic patients and diabetic rats may be due to difference in the ability of these two species to synthesize ascorbic acid. Difference in renal reabsorption of ascorbic acid may also be a relevant factor. The lower plasma and urinary ascorbic acid levels in diabetic patients with more severe hyperglycaemia indicates that this group of patients is particularly at risk of developing deficiency of this vitamin. As ascorbic acid has many important functions in the body, it may be necessary to supplement this vitamin in patients with chronically poorly controlled diabetes.
Diabetes Res Clin Pract 1990 Jul
PMID:Abnormalities of ascorbic acid metabolism and diabetic control: differences between diabetic patients and diabetic rats. 222 23


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