Diabetes Care, Vol 16, Issue 6 874-880, Copyright © 1993 by American Diabetes Association
Effect of added fat on plasma glucose and insulin response to ingested potato in individuals with NIDDM
MC Gannon, N Ercan, SA Westphal and FQ Nuttall
Metabolic Research Laboratory, Minneapolis Veterans Affairs Medical Center, MN 55417.
OBJECTIVE--In normal subjects, ingestion of butter with potato resulted in
considerably lower blood glucose levels but similar or higher insulin
concentrations compared with those observed in the same subjects after
potato ingestion alone. We determined whether butter ingested with potato
would result in a greater stimulation in insulin secretion than ingestion
of potato alone in subjects with NIDDM. RESEARCH DESIGN AND METHODS--Seven
male subjects with untreated NIDDM ingested 50 g CHO alone or 50 g CHO with
5, 15, 30, or 50 g fat as a breakfast meal. Fat was ingested in the form of
butter, and CHO was given in the form of potato. Subjects received 50 g
glucose on two separate occasions for comparative purposes. The subjects
also were given only water and were studied over the same time period
(water control). Plasma glucose, glucagon, alpha-amino nitrogen,
nonesterified fatty acids, serum insulin, C-peptide, and triglyceride
concentrations were determined over 5 h. The integrated area responses were
quantified over the 5-h period using the water control as a baseline.
RESULTS--The mean plasma glucose area response after ingestion of potato
with or without the various amounts of butter were all similar and were 82%
of that observed after ingestion of 50 g glucose. The mean insulin area
response to potato alone was 532 pmol.h.L-1. The mean insulin area
responses to potato plus 5,15,30, and 50 g of fat meals were 660,774,750,
and 756 pmol.h.L-1, respectively. Thus, the mean insulin areas were all
greater than for ingestion of potato alone, and a maximal response was
observed with addition of 15 g fat (1.4-fold). The C-peptide data did not
confirm an increase in insulin secretion. Overall the area responses after
ingestion of meals containing fat were not different from the response to
potato ingestion alone, although the responses were erratic. The glucagon
area response was positive after ingestion of all fat containing meals
except for that containing only 5 g fat, and there was a dose-response
relationship. The plasma alpha-amino nitrogen and nonesterified fatty acid
area responses were negative after potato ingestion and were not
significantly different when fat was added. The serum triglyceride
concentration increase was greater after the ingestion of butter with the
potato as expected. CONCLUSIONS--In contrast to the results in normal
subjects after ingestion of butter with potato, the glucose response was
not smaller in subjects with NIDDM. The insulin response was greater. The
insulin area response data indicated the presence of a dose-response
relationship. Whether similar responses will be observed with other dietary
fat and CHO sources remains to be determined.