Clinical significance of plasma mannose concentrations in healthy and diabetic dogs

Abstract

Circulating levels of monosaccharides can act as a reflection of systemic glucose/ energy metabolism. Characteristic changes observed in these levels can be seen in patients with diabetes and other metabolic disorders. There have been a few reports describing the significance of mannose metabolism as an energy source under physiological and pathological conditions. However, the relationship between circulating levels of mannose and the pathophysiology of diabetes mellitus are unknown in dogs. This study examined circulating levels of mannose between healthy control and diabetic dogs and evaluated the clinical significance of mannose levels in dogs. Diabetic dogs demonstrated a higher circulating level of mannose in comparison to normal healthy control dogs. Plasma mannose was positively correlated with plasma glucose and fructosamine, respectively. Interestingly, plasma mannose levels were affected by plasma insulin levels. In the context of feeding and glucose tolerance tests, plasma mannose levels responded to changes in circulating insulin levels. Circulating plasma mannose levels decreased after feeding in both control and diabetic animals in spite of observed insulin level differences. However, when glucose tolerance tests were given, a positive correlation between mannose levels and insulin levels was observed. Therefore, plasma mannose levels obtained via glucose tolerance testing may be used as a new diagnostic method for evaluating insulin resistance or deficiency in diabetic dogs.

Mannose metabolism: More than meets the eye

“…Higher doses cause mild gastro-intestinal discomfort, but no other side effects [44]. Pregnant women with diabetes mellitus show elevated mannose levels in fasted blood and amniotic fluid which correlated with high glucose concentration [45] and several show that mannose levels are closely linked to glucose metabolism [46,47]. How this impacts glycosylation is not known.…”

Metabolomic profiling to identify effects of dietary calcium reveal the influence of the individual and postprandial dynamics on the canine plasma metabolome

“…The postprandial decrease in mannose is consistent with previous reports in dog serum ( 31 ) , whilst this was not observed in humans where it was reported to increase about 4–6 h after a postprandial challenge test ( 9 ) . This difference may be because, unlike humans, in dogs mannose has been identified as an insulin-responsive sugar ( 32 ) .

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Model‐Based Interspecies Scaling of Glucose Homeostasis

“…The data included in the analysis was gathered from previously published studies, in which IVGTTs were performed; the studies are summarized in Table and included data from dogs ( n = 11), humans ( n = 24), mice ( n = 10), pigs ( n = 11), and rats ( n = 16). In the study performed in dogs and one of the human studies, a bolus dose of insulin was administered 20 minutes after the glucose dose; so‐called insulin‐modified IVGTT.…”

“…To determine if the allometrically scaled model can describe data from other studies as well as for a species that the model has not been developed on, the mean and SDs of glucose and insulin concentrations from published IVGTT studies performed in dogs, humans, pigs, monkeys, and rats were digitalized . Mice were not included because no study that fulfilled the inclusion criteria and presented glucose and insulin profiles was found for this species, except the study used for data analysis .…”