Biology Reference
In-Depth Information
concentrations over 8 h of the study in both normal and diabetic subjects
(
Conn & Newburgh, 1936
). Other studies also showed similar findings.
Glucose concentrations did not increase with ingestion of protein in both
normal and type 2 diabetic subjects, but there was increased insulin stimu-
lation and production (
Berger & Vongaraya, 1966; Fajans, Floyd, Knopf, &
Subjects, with and without diabetes, did not seem to show an increase in
blood glucose levels after ingestion of protein but the latter showed a stron-
ger insulin response compared to nondiabetics (
Berger & Vongaraya, 1966
).
Blood glucose concentrations were not exhibiting significant changes even
though there seemed to be large amounts of glucose being produced in sub-
jects and consistent rises in blood urea nitrogen (indicating protein utiliza-
tion). According to
Gannon and Nuttall (2010)
, although the D/N ratio
estimated the maximum amount of glucose that could be produced from
an ingested protein, these amounts were not apparent under normal phys-
iological conditions. Several other studies later also showed no change in
plasma glucose concentration from protein ingestion. When normal subjects
(
Krezowski et al., 1986
) ingested 50 g beef protein, the plasma glucose
concentration remained unchanged during the 4 h of the study, consistent
with earlier findings (
Berger & Vongaraya, 1966; Rabinowitz, Merimee,
Maffezzoli, & Burgess, 1966
). In type 2 diabetic subjects
(
Nuttall et al.,
1984
), glucose concentration was stable with relatively no change when pro-
tein only was given. Again, the ingestion of protein had very little effect on
glucose production in normal subjects and diabetics.
The glucose appearance rate following the ingestion of proteins in nor-
mal subjects and type 2 diabetics was investigated in two studies. Normal
subjects ingested 50 g of protein in the form of cottage cheese and the glu-
cose appearance rate in plasma was compared against a water control using a
constant infusion of 3H-glucose
(
Khan, Gannon, &Nuttall, 1992
). The total
amount of protein deaminated and converted to urea was 29.3 g with the
glucose appearing in the circulation as a result of amino acid metabolism
was approximately 10 g (
Khan et al., 1992
)
. Based on the gluconeogenic
potential of cottage cheese (42.3 g of glucose from 50 g of cottage cheese
protein), this accounted for about 43% protein metabolized (or 23% of
the total amount of protein ingested) with the fate of the rest remaining
unknown (
Khan et al., 1992
)
. In type 2 diabetics, insulin and glucagon con-
centration also increased following protein ingestion (
Gannon et al., 2001
)
.
The net amount of glucose estimated to be produced in type 2 diabetic sub-
jects (based on the quantity of amino acids deaminated) was approximately
