Isolated hyperglycaemia does not increase VLDL-triacylglycerol secretion in type 1 diabetic men.
OBJECTIVE
In type 1 diabetes, abnormalities of both glucose and lipoprotein metabolism are seen. The relationship between these factors is not understood, but studies indicate that hyperglycaemia may increase hepatic VLDL-triacylglycerol (VLDL-TG) secretion and reduce VLDL-TG fatty acid oxidation, which could lead to the development of dyslipidaemia. The aim of this study was to determine the isolated effect of hyperglycaemia on VLDL-TG and NEFA kinetics in men with type 1 diabetes.


METHODS
VLDL-TG and palmitate kinetics were measured in eight men with type 1 diabetes using ex vivo labelled VLDL-TG and palmitate tracers. A 2.5 h basal period (plasma glucose 5 mmol/l) was followed by a 4 h hyperglycaemic period (plasma glucose 16 mmol/l). Steady-state VLDL-TG kinetics (VLDL-TG secretion, clearance and oxidation rates) were assessed by an isotope dilution technique using an intravenous primed-constant infusion of ex vivo labelled [1-(14)C]VLDL-TG in combination with sampling of blood and expired air. Palmitate turnover was measured using [9,10-(3)H]palmitate.


RESULTS
The VLDL-TG secretion rate (36.0 ± 9.6 vs 30.8 ± 6.1 μmol/min, NS) and clearance rate (209 ± 30.4 vs 197 ± 41.7 ml/min, NS) were unchanged during the basal and hyperglycaemic periods, resulting in unchanged VLDL-TG concentrations (0.25 ± 0.11 μmol/l vs 0.28 ± 0.10 μmol/l, NS). In addition, VLDL-TG fatty acid oxidation and palmitate flux were not changed during hyperglycaemia.


CONCLUSIONS
Four hours of acute hyperglycaemia (16 mmol/l) without a concomitant increase in insulin does not alter VLDL-TG and NEFA kinetics in men with type 1 diabetes.


BACKGROUND
NCT01178957.
Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade 44, 8000, Aarhus C, Denmark, rfjohansen@ki.au.dk.
Rakel F
RF
Johansen
Esben
E
Søndergaard
Lars Peter
LP
Sørensen
Birgitte
B
Nellemann
Jens S
JS
Christiansen
Søren
S
Nielsen
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000503:physiopathology; D050171:Dyslipidemias / Q000097:blood*; D015309:Glucose Clamp Technique; D006801:Humans; D006943:Hyperglycemia / Q000097:blood*; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D050356:Lipid Metabolism; D008079:Lipoproteins, VLDL / Q000097:blood* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010168:Palmitates / Q000378:metabolism; D014280:Triglycerides / Q000097:blood* / Q000378:metabolism
D001786:Blood Glucose; D007328:Insulin; D008079:Lipoproteins, VLDL; D010168:Palmitates; D014280:Triglycerides; C030106:very low density lipoprotein triglyceride