NOCTURNAL AND POSTPRANDIAL METABOLISM IN DIABETES MELLITUS
with special reference to lipid intolerance and the second meal effect
By Mette Axelsen, Lundberg Laboratory for Diabetes Research, Institute of
Internal Medicine, Sahlgrenska University Hospital, S-413 45 Göteborg,
Sweden
ABSTRACT
Diabetes mellitus is a rapidly growing global health problem.
Modern, intensified therapy prevents or delays the microvascular
complications in both Type 1 and Type 2 diabetic patients. However,
intensified insulin therapy in Type 1 diabetes is associated with increased
risk of serious nocturnal hypoglycemia. In contrast, fasting hyperglycemia,
rather than hypoglycemia, is a major problem in Type 2 diabetes. One reason
for this is that the nocturnal plasma free fatty acid (FFA) levels, which
enhance the hepatic glucose production, are elevated. Around 40% of these
patients have established macroangiopathy already at the onset of the
disease. Thus, it is critically important to define early risk factors for
cardiovascular disease and that effective stategies for the prevention of
both macrovascular and microvascular complications are developed. The
present study evaluated the potential beneficial effects of bedtime
ingestion of a slowly digestible carbohydrate (uncooked cornstarch) on
nocturnal and morning postprandial blood glucose control and lipid levels
in Type 1 and Type 2 diabetic patients. Insulin sensitivity and
postprandial triglyceride (TG) levels were also studied in healthy,
normoglycemic individuals with a massive heredity for Type 2 diabetes.
Bedtime uncooked cornstarch exhibited a lente release profile, the peak
effect on nocturnal blood glucose being similar to the peak effect of NPH
insulin, ie, after ~4 hrs. In Type 1 diabetics, bedtime ingestion of ~20 g
of cornstarch led to a 70% reduction of nocturnal hypoglycemia without
altering HbA1c or fasting lipid levels. In Type 2 diabetes, bedtime
uncooked cornstarch ingestion led to sustained nocturnal insulinization and
FFA suppression. This was associated with improved fasting blood glucose
levels and glucose tolerance after breakfast, consistent with an overnight
second-meal effect. The same effect was not obtained with similar amounts
of rapid carbohydrates. The insulin secretory response during breakfast
also tended to be improved. In contrast, the postprandial lipemia was not
improved, probably because insulin resistance was not alleviated. It was
also demonstrated, for the first time, that normoglycemic and normolipemic
first-degree relatives of Type 2 diabetic patients, exhibit lipid
intolerance in that the postprandial TG response to a fat-rich meal was
~50% higher. This, in turn, suggests that an atherogenic lipid profile is
present already at this stage. In conclusion, bedtime ingestion of uncooked
cornstarch seems to be a feasible tool to balance the effect of NPH insulin
and, thus, to prevent nocturnal hypoglycemia in intensively treated Type 1
diabetic patients. Moreover, modulation of nocturnal plasma insulin and FFA
levels by slow-release cornstarch can improve the morning glycemic control,
possible due to relief of the "lipotoxic effect" of FFA on the ß-cell. The
finding of a lipid intolerance in healthy subjects with massive heredity
for Type 2 diabetes is a marker of an atherogenic lipid profile which
obviously can be present long before glucose tolerance is impaired.
Key words: diabetes, first-degree relatives, nocturnal, postprandial,
glucose, triglyceride, metabolism, free fatty acids (FFA), insulin, insulin
resistance, C-peptide, carbohydrates
ISBN: 91-628-3492-4. Göteborg 1999.
NOCTURNAL AND POSTPRANDIAL METABOLISM IN DIABETES MELLITUS
with special reference to lipid intolerance and the second meal effect
AKADEMISK AVHANDLING
som för avläggande av medicine doktors examen vid Göteborgs Universitet
kommer att offentligen försvaras i Aulan, Sahlgrenska
Universitetssjukhuset, Sahlgrenska, Göteborg
Torsdagen den 8 april 1999 kl. 13.00
av Mette Axelsen, Klinisk näringsfysiolog
Fakultetsopponent: David Jenkins, Toronto, Canada
Avhandlingen baseras på följande arbeten:
I. M Axelsen, C Wesslau, P Lönnroth, R Arvidsson Lenner & U Smith. Bedtime
uncooked cornstarch supplement prevents nocturnal hypoglycemia in
intensively treated IDDM subjects. J Internal Med 1999:249: in press.
II. M Axelsen, P Lönnroth, R Arvidsson Lenner & U Smith. Suppression of
nocturnal free fatty acid levels by bedtime cornstarch in NIDDM subjects.
Eur J Clin Invest 1997: 27:157-163.
III. M Axelsen, P Lönnroth, R Arvidsson Lenner, M-R Taskinen & U Smith.
Suppression of nocturnal FFA levels by bedtime carbohydrate supplement in
Type 2 diabetes: Effects on insulin sensitivity, lipids and glycemic
control. Submitted.
IV. M Axelsen, R Arvidsson Lenner, P Lönnroth & U Smith. Breakfast glycemic
response in patients with type 2 diabetes: Effects of bedtime dietary
carbohydrates. Eur J Clin Nutr 1999: in press.
V. M Axelsen, U Smith, JW Eriksson, M-R Taskinen & P-A Jansson.
Postprandial hypertriglyceridemia in normoglycemic first-degree relatives
of patients with Type 2 diabetes. Submitted.
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