Diabetes Care, Vol 21, Issue 1 16-22, Copyright © 1998 by American Diabetes Association
Stimulation of insulin secretion by fructose ingested with protein in people with untreated type 2 diabetes
MC Gannon, FQ Nuttall, CT Grant, S Ercan-Fang and N Ercan-Fang
Metabolic Research Laboratory, Minneapolis Veterans Affairs Medical Center, MN 55417, USA. ganno004@maroon.tc.umn.edu
OBJECTIVE: Ingested protein provides substrate for gluconeogenesis and
strongly stimulates insulin and glucagon secretion, but it has little
effect on the glucose concentration in people with type 2 diabetes.
Ingested fructose also is a substrate for gluconeogenesis, modestly
stimulates insulin and glucagon secretion, and has little effect on the
plasma glucose. Therefore we were interested in determining if ingestion of
fructose along with protein would result in an additive, greater than
additive, or less than additive effect on circulating insulin, glucagon,
and glucose concentrations. RESEARCH DESIGN AND METHODS: Seven male
subjects with untreated type 2 diabetes were fasted overnight and then were
given either 25 g fructose, 25 g protein, 25 g fructose plus 25 g protein,
or water only at 0800. Subjects also ingested 50 g glucose on two separate
occasions. Plasma glucose, insulin, C-peptide, glucagon, alpha-amino
nitrogen, urea nitrogen, nonesterified fatty acids, and triglyceride
concentrations were determined over the subsequent 5 h. RESULTS: The
glucose concentration was only modestly increased and the area responses
were similar when protein, fructose, or the combination was ingested. Thus,
the glucose response to the combination was less than additive. The insulin
area response to protein was 2.5-fold greater than to fructose, and the
response to the two nutrients was additive and quantitatively similar to
the response to 50 g glucose. The glucagon area response was less than
additive, i.e., there was an interaction between the protein and fructose
that resulted in a smaller than expected response. CONCLUSIONS: When
protein and fructose were ingested together, the insulin response was
similar to that following ingestion of 50 g glucose. It also was as
expected based on the response to the individual nutrients. In contrast,
the glucose and glucagon responses were significantly less than expected.
These data may be useful in dietary planning for subjects with type 2
diabetes.