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At least 19 recordsLinked to original sources
PubMed2026

Diagnostic utility of fasting versus non-fasting blood glucose: contextualising testing strategies-a narrative review.

Diabetes mellitus is a chronic metabolic disorder characterised by impaired glucose homeostasis, resulting in persistent hyperglycaemia. Accurate and prompt diagnosis is essential for early intervention and prevention of long-term complications. Fasting blood glucose levels have traditionally been central to the diagnosis and monitoring of diabetes mellitus. However, growing evidence highlights the clinical relevance of non-fasting glucose measures, including postprandial glucose, random plasma glucose, and glycated haemoglobin (HbA1c) levels. Practical challenges, safety concerns, and evolving insights into glucose physiology have prompted renewed interest in flexible and context-driven approaches to glucose testing. This narrative review examines the physiological basis of fasting and non-fasting glucose regulation and critically evaluates their roles in diabetes screening, diagnosis, and monitoring. It also discusses the strengths and limitations of measuring fasting blood glucose, oral glucose tolerance, HbA1c, random plasma glucose, postprandial glucose, and continuous glucose monitoring. Special attention is given to pre-analytical and practical considerations, patient safety, and the ability of non-fasting measures to capture early metabolic dysfunction and real-world glycaemic exposure. This article reviews evidence supporting the prognostic value of postprandial hyperglycaemia and the expanding role of non-fasting monitoring tools. Non-fasting glucose testing offers substantial advantages in terms of accessibility, safety, and clinical relevance, and is well-suited for population screening and routine diabetes monitoring. Fasting glucose testing remains essential for specific diagnostic and research applications, particularly when strict metabolic standardisation is required. A context-driven framework that prioritises non-fasting approaches while reserving fasting tests for targeted indications provides a balanced and patient-centred strategy for contemporary diabetes care.

Diabetes screening↗
PubMed1991

The effect of fasting, transit plus fasting, and administration of adrenocorticotropic hormone on the source and amount of weight lost by feeder steers of different ages.

Two trials (winter and summer) were conducted to determine effects of fasting and transportation and adrenocorticotropic hormone (ACTH) administration on the amount and source of weight lost by feeder steers. Sixteen steers, in each of two experiments, were adapted to metabolism stalls for 10 d, were fed medium-quality hay at 2.1% of BW for 3 d, and then were subjected to either fasting alone or fasting plus transit for 48 h. In Exp. 1 steers were randomly assigned to treatments. In Exp. 2 steers were blocked by age (OLD or YOUNG) and assigned to treatments. Fecal and urinary excretions accounted for 65 and 38% of the total weight lost in Exp. 1 and 2, respectively. Fasting plus transit did not consistently increase the amount of weight lost compared with fasting alone but increased (P less than .01) plasma glucose concentrations. Injection of ACTH before either fasting alone or fasting plus transit increased (P less than .05) the amount of weight lost as feces. Steers in the OLD group lost more weight during transit and fasting but regained the lost weight faster (P less than .01) during the recovery period than did steers in the YOUNG group. Injecting YOUNG steers with ACTH before fasting alone or fasting plus transit increased plasma fibrinogen (P less than .10) and serum glucose (P less than .05) concentrations more than ACTH injections in OLD steers. Although fasting and transit elicit mobilization of body nutrients and resulted in a loss of BW, these effects were quickly reversed during the poststress period.

Adrenocorticotropic Hormone↗
PubMed1979

Effect of fasting and fasting and refeeding on hepatic and renal gluconeogenic enzymes in the chicken.

The effect of fasting and fasting and refeeding on hepatic and renal gluconeogenic enzyme activities were studied in six-week-old chickens (Gallus domesticus: New Hampshire male x Columbian female). Hepatic pyruvate carboxylase appeared not to be affected by fasting, but the renal enzyme activity increased in four-day fasted chickens. The hepatic mitochondrial and cytosolic phosphoenolpyruvate carboxykinases were essentially not affected by fasting. The renal mitochondrial phosphoenolpyruvate carboxykinase showed a slight increase in activity only after a four-day fast, but the cytosolic enzyme activity increased markedly already after a two-day fast. Also the activities of the hepatic and renal fructose-1,6-diphosphatase and glucose-6-phosphatase increased markedly on fasting. Refeeding for four days after a four-day fast returned these enzyme activities to near control values.

Animals↗
PubMed1975

Adaptation to fasting in baboon. II. Regulation of lipolysis early and late in fasting.

Regulation of lipolysis by the sympathetic nervous system, basal insulin, and glucagon was studied in fasted baboons. Beta-Adrenergic mechanisms were evaluated by blockade with propranolol after 24, 40, and 65 h of fasting. Inhibition of lipolysis decreased with increasing duration of fasting. Insulin concentrations were markedly reduced by propranolol at all stages of fasting, whereas glucose and glucagon concentrations were unchanged. The roles of insulin and glucagon were evaluated by a 2-h infusion of somatostatin after 18 and 65 h of fasting. At both times, insulin and glucagon concentrations were markedly reduced. At 18 h of fasting but not at 65 h, lipolysis doubled. At both times the plasma glucose concentration fell 15-30%. At 18 h, preventing the decrease in glucose with glucose infusion prevented the increase in lipolysis. These data suggest that a beta-adrenergic mechanism is largely responsible for regulation of lipolysis early in fasting and that insulin, glucagon, and beta-adrenergic mechanisms play no major part in the maintenance of the accelerated lipolysis later in fasting.

Animals↗
PubMed1972

Glucose-induced alkalosis in fasting subjects. Relationship to renal bicarbonate reabsorption during fasting and refeeding.

This study documents the development of alkalosis in patients returning to caloric intake after a period of starvation and investigates the mechanisms responsible for this metabolic alteration. We studied the acid-base status, bicarbonate reabsorption, acid excretion, and sodium metabolism during fasting and glucose refeeding in 19 patients receiving sodium supplements. Metabolic alkalosis developed promptly in all of the subjects who terminated an 18 day fast with 300 g of glucose daily for 4 days. Tubular maximum reabsorptive capacity for bicarbonate and renal bicarbonate threshold determinations were performed at varying intervals in six and seven subjects, respectively, who had fasted for 3-18 days. The results demonstrated that bicarbonate reabsorptive capacity was normal or low during early fasting, markedly elevated during the 2nd wk; and moderately elevated during the 3rd wk of fasting. Glucose administration at all stages of fasting caused a further increase in bicarbonate threshold. Sodium balance during fasting with sodium supplements was found to follow a triphasic pattern, with the occurrence of a natriuresis during the 1st wk followed by a period of sodium retention after which neutral daily sodium balance was reestablished. Correlation of bicarbonate reabsorption with sodium homeostasis indicated a slight decrease in renal bicarbonate threshold during the natriuretic phase, a marked increase in bicarbonate reabsorption during the period of sodium retention, and a continued moderate elevation of threshold after sodium balance was reestablished. This relationship was interpreted to indicate that changes in bicarbonate reabsorption during fasting and refeeding may be secondary to alterations in the renal reabsorption of sodium.

Absorption↗
PubMed1986

Fasting and refeeding modulate neutral amino acid transport activity in the basolateral membrane of the rat exocrine pancreatic epithelium: fasting-induced insulin insensitivity.

The effects of fasting and refeeding on amino acid transport in the perfused rat exocrine pancreas were investigated using a rapid dual tracer dilution technique. Unidirectional amino acid influx (15 s) was quantified (relative to the extracellular tracer D-mannitol) over a wide range of perfusate concentrations in pancreata isolated frm fed and 24 h, 48 h, and 72 h fasted and 72 h fasted and refed (24 h) animals. In fed animals transport of phenylalanine (1-24 mM) and L-serine (1-50 mM) was saturable and weighted non-linear regression analyses of the overall transport indicated an apparent Kt = 10 +/- 3 mM and Vmax = 7.0 +/- 1.0 mumol/min per g (n = 7) for phenylalanine and Kt = 16 +/- 3 mM and Vmax = 20.6 +/- 2.1 mumol/min per g (n = 5) for serine. Fasting animals for 24 h or 48 h did not change the kinetics of either phenylalanine or serine transport. After a 72 h fast the rate of phenylalanine transport (Vmax = 15.9 +/- 2.9 mumol/min per g, n = 5) was enhanced whereas the transport affinity (Kt = 11 +/- 3 mM) remained unaltered. L-Serine transport was essentially unaltered. When 72 h fasted animals were refed for 24 h the Vmax for phenylalanine transport was reduced to values observed in fed animals. In parallel experiments refeeding had no significant effect on serine transport. Perfusion of pancreata isolated from 72 h fasted animals with bovine insulin (1 mU/ml or 1 microU/ml) did not stimulate either phenylalanine or serine transport.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1978

The effect of ten days of fasting on various aspects of carbohydrate metabolism in obese diabetic subjects with significant fasting hyperglycemia.

Patients with nonketotic diabetes mellitus, who were both obese and had significant fasting hyperglycemia (mean plasma glucose = 310 mg/100 ml), were fasted for 10 days. There was a prompt drop of plasma glucose levels as the result of the caloric deprivation with a mean fall of approximately 200 mg/dl at the end of the fast. The drop in plasma glucose level that occurred during the fast was associated with a drop in plasma insulin level. Fasting plasma glucose concentration rose immediately after food intake was resumed and stabilized within 3--4 days at levels halfway between the initial and the lowest value. At this time, the patients also seemed capable of disposing of an oral glucose load more efficiently. The apparent improvement in carbohydrate homeostasis observed after the fast could not be attributed to an increase in insulin response, but was associated with some amelioration of the insulin resistance that characterizes these patients. Unfortunately, the beneficial effects of the 10-day period of caloric deprivation were transitory and fasting plasma glucose values had returned to prefast levels in most patients within a few months.

Adult↗
PubMed1989

Double atrial and double ventricular responses during slow-fast fast-slow atrioventricular nodal reentrant tachycardia.

A case was described with fast-slow form of atrioventricular nodal reentrant tachycardia as related with simultaneous fast and slow pathway conduction both antegrade and retrograde. Fast-slow form of tachycardia was induced by premature right atrial stimulation or incremental right ventricular pacing when the last paced beat conducted to the atria via both fast and slow pathways of the atrioventricular node causing double atrial response. Fast-slow form of tachycardia was spontaneously shifted to slow-fast form when the atrial echo, possibly through the retrograde intermediate pathway, was conducted antegradely over the fast and slow pathways simultaneously, producing double ventricular response.

Adolescent↗
PubMed1992

Effects of fasting, refeeding, and fasting with T3 administration on Na-K,ATPase in rat skeletal muscle.

It is known that Na-K,adenosine triphosphatase (ATPase) in cell membranes represents an important consumer of cellular energy, eg, adenosine triphosphate (ATP), and that the concentration and activity of this enzyme change in a dose-dependent manner with serum thyroid hormone levels. To examine the hypothesis that low triiodothyronine (T3) syndrome represents a cellular adaptation in generalized severe illnesses that saves tissue energy expenditure, we measured the muscle Na-K,ATPase concentration and its activity in rats that led to low T3 syndrome induced by fasting. The Na-K,ATPase concentration was measured by 3H-ouabain binding to soleus muscle, and its activity was measured by 42K uptake in the contralateral soleus muscle. The effects of refeeding or T3 administration on Na-K,ATPase in soleus muscle in fasted rats were also examined. Na-K,ATPase concentration and activity were both increased in hyperthyroid rats and decreased in hypothyroid rats. In the fasting state, they were decreased to as low as the levels seen in hypothyroidism. Furthermore, with fasting + refeeding or fasting + T3 administration, Na-K,ATPase in soleus muscle returned to the normal level. These results suggest that tissue energy expenditure, as assessed by Na-K,ATPase, in skeletal muscles of fasted rats with low T3 syndrome is actually decreased to levels seen in hypothyroidism, due at least partly to the decrease in serum T3 concentrations, and that there exist some adaptation mechanisms in the peripheral tissues for the accommodation of energy metabolism in the body through decreased thyroxine (T4) to T3 conversion.

Adenosine Triphosphate↗
PubMed1992

Effect of human mammary MX-1 tumor on plasma free fatty acids in fasted and fasted-refed nude mice.

We hypothesized that tumor-bearing (TB) nude mice, because they are reported to have no detectable, circulating tumor necrosis factor (TNF)/cachectin, would regulate their plasma free fatty acid (FFA) levels normally when fasted and refed. We compared levels of individual plasma FFA in response to fasting (24 hr) and to refeeding (for 20 hr after fasting) a fat-free, 65% sucrose diet in control, nude mice and in mice bearing 1.3 +/- 0.4 g MX-1 tumors. Total plasma FFA levels were typically high in 24-hr fasted mice [mean concentrations in microM +/- SE (n); controls 515 +/- 63 (6); TB, 625 +/- 63 (6)]. FFA levels were reduced by 65% in each group in response to refeeding. Each major plasma FFA species fell in response to refeeding, except arachidonate, which did not change significantly (fasted vs. fasted-refed concentrations) in either controls or TB mice. In refed mice, the molar FFA ratio of oleate to linoleate rose; however, that of oleate to arachidonate fell markedly. TB nude mice had normal appetites. We conclude that all species of FFA were mobilized from adipose tissue in a normal manner in TB nude mice; therefore, regulation of adipose triacylglycerol fatty acid mobilization (as plasma FFA) by dietary sugar is probably not affected by MX-1 tumor growth in these mice. Our findings are consistent with the hypothesis that nude mice may be unable to secrete TNF/cachectin in response to tumor growth, but they do not establish whether or not endogenous, circulating TNF/cachectin increases FFA mobilization in any TB animal.

Adipose Tissue↗
PubMedDate not supplied

Synthesis of fast myosin induced by fast ectopic innervation of rat soleus muscle is restricted to the ectopic endplate region.

Skeletal muscle fibres, long multinucleated cells, arise by fusion of mononucleated myoblasts to form a myotube that matures into the adult fibre. The two major types of mature fibre, fast and slow fibres, differ physiologically in their rate of isotonic shortening. At the molecular level these type-specific physiological properties are ascribed to different isoforms of myosin, a major protein involved in shortening. Differentiation of fast and slow fibres seems to be under the control of motoneurones, and mature fibres are innervated by only one motoneurone. When rat soleus muscle (SOL, a slow muscle) is dually innervated with a fast nerve, it acquires some properties of a fast muscle, that is, low sensitivity to caffeine and high glycogen content. We report here that in dually innervated soleus muscle the foreign fast nerve induces synthesis of fast isoforms of myosin, but only in the segment of the muscle fibre that is close to the foreign endplate. The localized influence of the nerve endplates suggest that factors controlling the phenotypic expression of the muscle fibre have a short range of activity.

Animals↗
PubMed1989

Restoration of fast muscle characteristics following cessation of chronic stimulation: physiological, histochemical and metabolic changes during slow-to-fast transformation.

Implantable electronic stimulators were used to subject fast-twitch tibialis anterior and extensor digitorum longus muscles of adult rabbits to a chronically increased level of use. Stimulation was discontinued after 6 weeks and physiological, histochemical and biochemical properties of the muscles were examined at intervals over the ensuing 20 weeks. Previous work had shown that 6 weeks of stimulation was sufficient to bring about a substantial transformation of type in fast-twitch muscles, which then exhibited much of the character of muscles of the slow-twitch type. The present experiments showed that these stimulation-induced changes were completely reversible. The time-course of reversion was such that the muscles had recovered their original fast properties by about 12 weeks after the cessation of stimulation. The contractile characteristics and post-tetanic potentiation typical of fast muscle returned rapidly, in only 3-4 weeks, and over the same period the proportion of histochemical type 1 fibres declined from about 70% to control levels. Changes in fatigue-resistance, capillary density and enzyme activity followed a more prolonged time-course; in particular, the decline in the activity of enzymes of oxidative metabolism corresponded closely to that already established for the mitochondrial volume fraction. Reacquisition of fast properties was not accompanied by any changes in specific force-generating capacity. Observations from these experiments and from a related morphological study fit into a 'first-in, last-out' pattern for the response to stimulation and recovery. The slow-to-fast reversion that takes place during the recovery period provides a further opportunity for testing causal associations within the events underlying type transformation. It has important consequences for therapeutic applications that make use of the fatigue-resistant character of chronically stimulated muscle.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1975

A new isoniazid preparation designed for moderately fast and "fast" metabolizers of the drug.

The bioavailability of a new isoniazid preparation consisting of 37% ordinary isoniazid (INH) and 63% matrix component was investigated in 11 slow, 8 moderately fast, and 9 "fast" acetylators of the drug. Initially, a 15 mg/kg dose of normal INH was administered to all the participants. In addition, the two groups of fast metabolizers received 30 and 45 mg INH-matrix/kg, respectively, with a one-week interval between the test doses. These high dosages of the INH-matrix could be given without encountering toxic reactions because of the delayed absorption of the matrix formulation. In moderately fast acetylators, with a triple dose of matrix isoniazid, it was possible to mimic the blood levels produced by 15 mg ordinary INH/kg in slow inactivators. However, in "fast" acetylators the blood concentrations achieved with the 45 mg/kg dose of INH-matrix were somewhat lower. This study also showed that a large input rate is essential to procure the required, high blood levels in fast metabolizers. The therapeutic implications of the results of this bioavailability trial are discussed.

Acetylation↗
PubMed1987

Fasting gastrinemia and elevated supersaturation with hydroxyapatite of fasting urine--observations in renal calcium stone patients and controls.

We evaluated serum gastrin, acid-base status, variables of mineral metabolism in fasting blood, as well as pH, relative supersaturation of stone forming constituents, and crystalluria in the associated fasting urine, of control subjects (n = 12), and in age- and weight-matched male normocalciuric (n = 12) and hypercalciuric (n = 12) patients with idiopathic recurrent calcium urolithiasis (RCU). In RCU, mineral metabolism and acid-base data are unchanged, whereas mean serum gastrin is only insignificantly higher as compared to controls. Subclassification of all participants into categories with either high-normal or low-normal gastrin reveals that in RCU with low-normal gastrin there is a higher-than-normal urinary pH and significantly elevated supersaturation of urine with hydroxyapatite. Crystalluria and stone analysis support the assumption that the physico-chemical environment accompanied by low gastrin levels predisposes to urinary precipitation of calcium phosphate with subsequent formation of a stone nidus. pH in fasting urine and integrated fasting serum gastrin correlate significantly, suggesting that low fasting serum gastrin in RCU patients may be considered a risk factor for calcium phosphate stone formation.

Acid-Base Equilibrium↗
PubMed1979

Tissue and serum somatostatin-like immunoreactivity in fed, 15-h-fasted, and 72-h-fasted rats.

Somatostatin-like immunoreactivity (SLI) was measured in extracts of gastric antrum, colon, pancreas, and central nervous system, as well as in unextracted portal and inferior vena caval serum from fed, 15-h-fasted, and 72-h-fasted rats. No differences were found in SLI in the central nervous system of the three groups. However, striking variations were found in the gastrointestinal tract and pancreas; the antrum, colon, and pancreas of 15-h-fasted rats contained the least SLI, the content being significantly elevated in these three areas after feeding and after a 72-h fast. Portal serum levels were highest after feeding but lowest in 72-h-fasted rats, in spite of high intestinal and pancreatic SLI content in both. These tissue and serum differences suggest a physiologic role for SLI in nutrient homeostasis not only at tissue level, but also putatively as a hormone in the portal system.

Animals↗
PubMed1979

[Enzyme arrangement of various tissues in swine. 1. Studies of the effect of 32 hours of fasting, administration of actinomycin D, and fasting in combination with administration of actinomycin D on crude protein level, activities of GOT, GTP, fructose-1,6-diphoaphatase as well as ATPase of liver, kidneys and semitendinous muscle in newborn piglets].

The effects of sufficient milk intake as well as of 32 hours of fasting after birth, administration of actinomycin D (intraperitoneal application of 1 mg/kg five weight), and fasting in combination with actinomycin D on the development of body and liver weights, crude protein levels in homogenate and supernatant of liver, kidneys, and M. semitendinosus as well as on the activities of certain tissue enzymes were analysed with four groups of piglets (n = 4). Fasting, administration of actinomycin, and fasting in combination with actinomycin D resulted in rapid reduction in body and liver weights, while the crude protein levels in those tissues were not affected with significance. GOT and fructose-1,6-diphosphatase activities in supernatant from liver tended to decline under fasting conditions. The ATPase activity in the homogenate of the above tissues did not change in response to differentiated treatment.

Adenosine Triphosphatases↗
PubMed1982

Comparison of actomyosin and myosin from rat muscles with marked differences in the ratio of fast oxidative glycolytic and fast glycolytic muscle fibres.

Actomyosin and myosin were isolated from rat fast muscles, differing in the percentage of fast oxidative glycolytic and fast glycolytic fibres. The dependence of actomyosin ATPase activity from these muscles on the pH corresponds to the previously found dependence of myofibrillar ATPase on the pH, followed histochemically. The myosins isolated from the tensor fascia latae muscle (fast glycolytic) and extensor digitorum longus and tibialis anterior muscles (predominantly fast oxidative glycolytic muscles) differ in the effect of mild acid pre-incubation on myosin ATPase activity. They do not contain the same amount of LC3 and also tryptic peptides of these myosins display a slightly different pattern, as revealed by SDS gel electrophoresis.

Actomyosin↗
PubMed1988

Fatty acid metabolism of the perfused caudate lobe from livers of fed and fasted non-pregnant and fasted late pregnant ewes.

1. Fatty acid metabolism has been compared in perfused liver lobes from fed and fasted non-pregnant sheep and fasted pregnant sheep to provide further information on the control of ketogenesis in this species. 2. Ketogenesis from exogenous palmitate was greatest in lobes from fasted pregnant sheep and least in lobes from fed non-pregnant sheep, whereas rates of ketogenesis from exogenous octanoate (0.4 mM) were similar in lobes from sheep in all three states. 3. High rates of ketogenesis from endogenous fatty acids occurred in perfused lobes from fasted pregnant sheep, apparently owing to enhanced lipolysis. 4. Activities of glycerol-3-phosphate acyltransferase, carnitine palmitoyl transferase (CPT) and other enzymes involved in ketone production did not change with physiological state; sheep differ markedly from rats in this respect. 5. The results suggest that the primary point of control of ketogenesis within the liver of sheep is at the level of CPT; the lack of change in maximum CPT activity suggests that control by modulators of this enzyme activity is even more important in sheep than in rats.

Animals↗