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

In the fasted rat, efficient glucose-stimulated insulin secretion (GSIS) is absolutely dependent on an elevated level of circulating free fatty acids (FFAs). To determine if this is also true in humans, nonobese volunteers were fasted for 24 h (n = 5) or 48 h (n = 5), after which they received an infusion of either saline or nicotinic acid (NA) to deplete their plasma FFA pool, followed by an intravenous bolus of glucose. NA treatment resulted in a fall in basal insulin concentrations of 35 and 45% and in the area under the insulin response curve (area under the curve [AUC]) to glucose of 47 and 42% in the 24- and 48-h fasted individuals, respectively. The 48-h fasted subjects underwent the same procedure with the addition of a coinfusion of Intralipid plus heparin (together with NA) to maintain a high concentration of plasma FFAs throughout the study. The basal level and AUC for insulin were now completely normalized (C-peptide profiles paralleled those for insulin). To assess the effect of an overnight fast, nonobese (n = 6) and obese (n = 6) subjects received an infusion of either saline or NA, followed by a hyperglycemic clamp (200 mg/dl). The insulin AUC in response to glucose was unaffected by lowering of the FFA level in nonobese subjects, but fell by 29% in the obese group. The data clearly demonstrate that in humans, the rise in circulating FFA levels after 24 and 48 h of food deprivation is critically important for pancreatic beta-cell function both basally and during subsequent glucose loading. They also suggest that the enhancement of GSIS by FFAs in obese individuals is more prominent than that seen in their nonobese counterparts.
Diabetes 1998 Oct
PMID:Circulating fatty acids are essential for efficient glucose-stimulated insulin secretion after prolonged fasting in humans. 975

Dyslipidemia in patients with diabetes constitutes quantitative and qualitative abnormalities in all classes of lipoproteins and may be a significant contributor to the high risk of atherosclerosis in these patients. A step-care approach to therapy of diabetic dyslipidemia, including hygienic measures (diet and increased physical activity), hypoglycemic drugs, and lipid-lowering drugs, is recommended. The choice of lipid-lowering drugs depends on severity of hypertriglyceridemia. Statins and bile-acid-binding resins are the choice of therapy for diabetic dyslipidemia; however, for severely hypertriglyceridemic patients, fibric acid derivatives should be used. Nicotinic acid worsens hyperglycemia and, therefore, should be avoided. The value of estrogen replacement therapy in postmenopausal women with diabetes has not been established.
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PMID:Dyslipoproteinemia and diabetes. 978 56

Uncoupling proteins 3 and 2 (UCP3 and UCP2) are two newly cloned genes that have been implicated in the regulation of lipids as fuel substrate in skeletal muscle on the basis that their mRNA expressions are upregulated during starvation (when fat stores are being rapidly mobilized) and downregulated during the early phase of refeeding (when fat stores are being rapidly replenished). To test the hypothesis that circulating free fatty acids (FFAs) may have a physiological role as an interorgan signal linking these dynamic changes in the fat stores to skeletal muscle expression of UCP3 and UCP2, the mRNA levels of these UCP homologs were examined in fed and fasted rats treated with the antilipolytic agent nicotinic acid. In 46-h fasted rats, we observed a threefold increase in serum FFA levels and increases in UCP3 and UCP2 mRNA levels that were more marked in the gastrocnemius and tibialis anterior muscles (predominantly fast-twitch fibers) than in the soleus muscle (predominantly slow-twitch fibers). Treatment with nicotinic acid blunted the fasting-induced increase in serum FFA levels and prevented the increase in mRNA levels of UCP3 and UCP2 in the soleus muscle, but had little or no effect on the elevated mRNA levels of these UCP homologs in the gastrocnemius and tibialis anterior muscles. Furthermore, treatment of ad libitum-fed animals with nicotinic acid resulted in a twofold reduction in serum FFA levels (i.e., by a magnitude similar to that observed during early refeeding) and significant reductions in UCP3 and UCP2 mRNA levels in the soleus muscle, but not in the gastrocnemius or tibialis anterior muscles. These results revealed a muscle-type dependency in the way UCP2 and UCP3 gene expression in skeletal muscle is regulated, and suggest that the hypothesis that circulating FFAs function as an interorgan signal between fat stores and skeletal muscle UCP3 and UCP2 gene expression is adequate only for slow-twitch (oxidative) muscles. Consequently, a signal(s) other than circulating FFAs must be implicated in the link between dynamic changes in body fat stores and UCP expression in predominantly fast-twitch (glycolytic/oxidative-glycolytic) muscles, which constitute the major fiber type of the total skeletal muscle mass and which have high susceptibility to developing insulin resistance and impairment in substrate utilization in metabolic diseases.
Diabetes 1998 Nov
PMID:Interorgan signaling between adipose tissue metabolism and skeletal muscle uncoupling protein homologs: is there a role for circulating free fatty acids? 979 37

The electrical activity of pancreatic beta-cells in 48-h fasted mice has been recorded in vivo. Their electrical activity is exceedingly high at low levels of blood glucose when compared with control animals. For example, at a blood glucose concentration of 4.5 mmol/l, at which beta-cells are permanently hyperpolarized in control animals, fasted animals show continuous spiking activity. In fasted animals, hyperpolarization only occurs at glycemias below 2.2 mmol/l. As in fed animals, the electrical activity in fasted mice can be decreased or suppressed by the injection of diazoxide, indicating the participation of K(ATP) channels. The treatment of fasted animals with nicotinic acid, an inhibitor of lipolysis, produces a decrease in the levels of free fatty acids (FFAs) and a decrease in electrical activity, thereby restoring the dose-response curve for glucose in fasted animals to values close to those found in fed animals. Conversely, the injection of palmitic acid produces an increase in electrical activity without a change in blood glucose. These results point to FFAs as important regulators of electrical activity during fasting in vivo. They also indicate a dissociation of electrical activity and insulin release in fasted animals, since an increase in electrical activity is not associated with increased insulin secretion.
Diabetes 1998 Nov
PMID:Increased levels of free fatty acids in fasted mice stimulate in vivo beta-cell electrical activity. 979 39

The data for an independent association between triglyceride concentrations and risk for coronary artery disease (CAD) are equivocal, unlike the data for low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol, which show strong, consistent, and opposing correlations with CAD risk. There is some evidence for triglyceride as an independent risk factor in certain subgroups, for example, women 50-69 years of age (Framingham Heart Study) and in patients with noninsulin-dependent diabetes. However, the evidence is stronger for triglyceride as a synergistic CAD risk factor. For example, patients with the "lipid triad" of high LDL cholesterol, low HDL cholesterol, and high triglyceride accounted for most of the event reduction with lipid-lowering therapy in the Helsinki Heart Study. An important confounder of the correlation between triglyceride and CAD risk is the heterogeneity of triglyceride-rich lipoproteins: the larger triglyceride-rich particles are thought not to be associated with CAD risk, whereas the smaller (and denser) particles are believed to be atherogenic. At present, measurement of fasting triglyceride levels and triglyceride assessment in conjunction with LDL cholesterol and HDL cholesterol concentrations are the most practical methods of evaluating hypertriglyceridemia in CAD risk, although postprandial lipemia may prove a better indicator of atherogenicity. Management of hypertriglyceridemia should initially focus on nonpharmacologic therapy (i.e., diet, exercise, weight control, and alcohol reduction). In diabetic patients, meticulous glycemic control is also important. However, if this approach proves inadequate, there are several pharmacologic options. Fibrates may be effective in decreasing triglyceride and increasing HDL cholesterol. Nicotinic acid (niacin) has been shown to decrease triglyceride, increase HDL cholesterol, lower LDL cholesterol, and decrease lipoprotein(a); it also decreases fibrinogen. The statins appear to be effective in decreasing triglyceride and LDL cholesterol in hypertriglyceridemia; however, they do not normalize metabolism of apolipoprotein B, and HDL cholesterol may remain low. Therefore, combination with a fibrate or niacin may be appropriate. Attention to hypertriglyceridemia with respect to increased CAD risk represents an important step in assessing global risk for CAD development.
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PMID:Triglyceride as a risk factor for coronary artery disease. 981

Usual risk factors for coronary artery disease account for only 25-50% of increased atherosclerotic risk in diabetes mellitus. Other obvious risk factors are hyperglycemia and dyslipidemia. However, hyperglycemia is a very late stage in the sequence of events from insulin resistance to frank diabetes, whereas lipoprotein abnormalities are manifested during the largely asymptomatic diabetic prodrome and contribute substantially to the increased risk of macrovascular disease. The insulin-resistant diabetes course affects virtually all lipids and lipoproteins. Chylomicron and very-low-density lipoprotein (VLDL) remnants accumulate, and triglycerides enrich high-density lipoprotein (HDL) and low-density lipoprotein (LDL), leading to high levels of potentially atherogenic particles and low levels of HDL cholesterol. Hyperglycemia eventually impairs removal of triglyceride-rich lipoproteins, the accumulation of which accentuates hypertriglyceridemia. As triglycerides increase-still within the so-called normal range-abnormalities in HDL and LDL became more apparent. Thus, when triglycerides are >200 mg/dL, LDL particles are small and dense (when they are <90 mg/dL, the particles are of the large, buoyant variety). The atherogenicity of small, dense LDL particles is attributed to their increased susceptibility to oxidation, but in many patients they may be a marker for insulin resistance or the presence of atherogenic VLDL. Hypertriglyceridemia is associated with atherosclerosis because (1) it is a marker for insulin resistance and atherogenic metabolic abnormalities; and (2) the small size of triglyceride-enriched lipoproteins enables them to infiltrate the blood vessel wall where they are oxidized, bind to receptors on macrophages, and ingested, leading to the development of the atherosclerotic lesion. Various studies (primary prevention with gemfibrozil: Helsinki Heart Study; secondary prevention with simvastatin and pravastatin: Scandinavian Simvastatin Survival Study [4S] and Cholesterol and Recurrent Events [CARE], respectively) have demonstrated that lipid-lowering therapy in type 2 diabetes is effective in decreasing the number of cardiac events. Risk reduction was 22% to 50% (statins) and approximately 65% (fibrate) relative to placebo. It was also noted (in 4S and CARE) that the risk of major coronary events in untreated diabetic patients was 1.5-1.7-fold greater than in untreated nondiabetic patients. Although gemfibrozil (fibric acid derivative) is more effective in decreasing triglycerides and increasing HDL cholesterol in diabetic patients than the statins, it does not change and may even increase LDL-cholesterol levels (fenofibrate may be an exception, decreasing LDL cholesterol by 20-25% in some studies). However, gemfibrozil does increase LDL particle size. Nevertheless, the statins are the current lipid-lowering drugs of choice because the change in LDL-cholesterol-to-HDL-cholesterol ratio is better than with gemfibrozil. Moreover, the diabetic patient may be more likely to benefit from statin therapy than the nondiabetic patient. It should be noted that, in theory, nicotinic acid can correct or improve all lipid or lipoprotein abnormalities in patients with type 2 diabetes. Unfortunately, it is relatively contraindicated because it causes insulin resistance and may precipitate or aggravate hyperglycemia (in addition to its other well-known side effects such as flushing, gastric irritation, development of hepatotoxicity, and hyperuricemia). It is unknown at present whether newer formulations such as once-daily Niaspan may be better tolerated in diabetes. In any case, most patients with type 2 diabetes have risk factors for coronary artery disease and qualify for aggressive LDL cholesterol-lowering therapy. At the same time, it is presently unknown whether improved glycemic control decreases coronary artery disease risk in such patients.
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PMID:Diabetic dyslipidemia. 991 65

The objective of this study was to assess the role of free fatty acids (FFAs) as insulin secretagogues in patients with type 2 diabetes. To this end, basal insulin secretion rates (ISR) in response to acute increases in plasma FFAs were evaluated in patients with type 2 diabetes and in age- and weight-matched nondiabetic control subjects during 1) intravenous infusion of lipid plus heparin (L/H), which stimulated intravascular lipolysis, and 2) the FFA rebound, which followed lowering of plasma FFAs with nicotinic acid (NA) and was a consequence of increased lipolysis from the subject's own adipose tissue. At comparable euglycemia, diabetic patients had similar ISR but higher plasma beta-hydroxybutyrate (beta-OHB) levels during L/H infusion and higher plasma FFA and beta-OHB levels during the FFA rebound than nondiabetic control subjects. Correlating ISR with plasma FFA plus beta-OHB levels showed that in response to the same changes in FFA plus beta-OHB levels, diabetic patients secreted approximately 30% less insulin than nondiabetic control subjects. In addition, twice as much insulin was secreted during L/H infusion as during the FFA rebound in response to the same FFA/beta-OHB stimulation by both diabetic patients and control subjects. Glycerol, which was present in the infused lipid (272 mmol/l) did not affect ISR. We concluded that 1) assessment of FFA effects on ISR requires consideration of effects on ISR by ketone bodies; 2) ISR responses to FFA/beta-OHB were defective in patients with type 2 diabetes (partial beta-cell lipid blindness), but this defect was compensated by elevated plasma levels of FFAs and ketone bodies; and 3) approximately two times more insulin was released per unit change in plasma FFA plus beta-OHB during L/H infusion than during the FFA rebound after NA. The reason for this remains to be explored.
Diabetes 1999 Mar
PMID:Effects of fatty acids and ketone bodies on basal insulin secretion in type 2 diabetes. 1007 59

To obtain optimal image quality in myocardial viability studies, it is recommended that 18F-fluordeoxyglucose (18F-FDG) studies be performed with hyperinsulinaemic glucose clamping. 18F-FDG imaging after oral administration of acipimox, a nicotinic acid derivative, results in comparable image quality to clamping. Twenty consecutive patients (7 with diabetes mellitus) with angiographically confirmed coronary artery disease and similar demographic/clinical profiles were randomly allocated to gated cardiac 18F-FDG-PET with a standard euglycaemic hyperinsulinaemic clamp protocol or using a combination of oral administration of acipimox and the insulin clamp technique. The image quality, expressed as the myocardial-to-blood pool activity ratio, was superior in the combined protocol compared with the insulin clamping technique alone (3.37 +/- 1.46 vs 2.27 +/- 0.62, P = 0.037). Although there were no significant differences in plasma insulin and free fatty acids concentrations between the two protocols, plasma glucose concentrations obtained with the standard protocol were elevated compared with the combined protocol (11.1 +/- 3.7 vs 6.3 +/- 3.0 mM during clamping; 10.2 +/- 3.3 vs 5.5 +/- 3.0 mM during acquisition). We conclude that gated 18F-FDG-PET imaging after oral administration of acipimox plus insulin clamping yields image quality superior to that obtained with clamping alone.
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PMID:Combined hyperinsulinaemic glucose clamp and oral acipimox for optimizing metabolic conditions during 18F-fluorodeoxyglucose gated PET cardiac imaging: comparative results. 1058 93

The 'metabolic syndrome' is a special clinical entity characterized by upper body segment obesity (android obesity), together with one or more of a constellation of metabolic disorders that includes glucose intolerance, which may amount to frank diabetes mellitus, hypertension, cardiovascular lesions, hyperuricemia, and dyslipidemias (hypercholesterolemia, hypertriglyceridemia and reduced serum HDL). Recently, lipoprotein (Lp) (a) proved to be a new member in this syndrome. Lp(a) has the distinctive feature of containing apolipoprotein (a), which is a glycoprotein linked to apo B100, and has a similarity to plasminogen; it is also structurally related to LDL. Lp(a) is a macromolecular complex which is genetically determined, and has been identified as an independent risk factor for premature coronary artery disease (CAD). It is elevated in diabetic and non-diabetic android obese subjects, and aggravates the atherogenic effect of diabetes mellitus. Lp(a) is poorly influenced either by dietary measures or by hypolipidemic drugs. Unfortunately, few pharmacologic agents, such as niacin, nicotinic acid, sex hormones (estrogen and testosterone), alcohol and neomycin, affect Lp(a).
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PMID:Lipoprotein (a) in android obesity and NIDDM: a new member in 'the metabolic syndrome'. 1066 39

Nicotinamide adenine dinucleotide (NAD) and its derivatives NADH, NADP and NADPH have regulatory functions in the generation of triose phosphates and pyruvate from glucose. In many studies of the influence of the diabetic state on relationships between pyridine nucleotide and glucose metabolism, the focus has been on the sorbitol pathway. Less attention has been paid to other aspects of the role of pyridine nucleotides in pyruvate formation from glucose, in particular the effects of the NAD precursors nicotinamide and nicotinic acid on glucose metabolism. This paper reviews current knowledge of the involvement of pyridine nucleotides and their precursors in glucose catabolism in the normal and diabetic state. Reference is also made to the following three current hypotheses for mechanisms underlying diabetic microangiopathy: 1. Chronic glucose overutilization, caused by hyperglycemia, in tissues which lack insulin receptors and therefore are freely permeable to glucose. 2. Enhancement of sorbitol pathway activity with an ensuing decrease in the ratio of NAD/NADH. 3. Enhanced utilization of both glucose and pyridine nucleotides in formation of triose phosphates and pyruvate. Therapy with NAD precursors like nicotinamide might have corrective effects on these proposed biochemical aberrations, thereby retarding progression of microangiopathy.
Diabetes Metab Res Rev
PMID:Pyridine nucleotides in glucose metabolism and diabetes: a review. 1070 37


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