Preserved insulin response to tolbutamide in hepatocyte nuclear factor-1alpha mutation carriers.
OBJECTIVE
Diabetic subjects with mutations in the gene encoding hepatocyte nuclear factor (HNF)-1alpha (MODY3) are prone to develop hypoglycaemia at low doses of glibenclamide, interpreted as sulphonylurea hypersensitivity. The present study was undertaken to compare the plasma insulin responses to glucose and tolbutamide in HNF-1alpha mutation carriers with those of healthy control subjects.


METHODS
Seven mutation carriers; three normoglycaemic, two with impaired glucose tolerance, and two with newly detected diabetes, underwent an oral glucose tolerance test and a tolbutamide-modified intravenous glucose tolerance test with measurements of plasma insulin. Twenty-two healthy subjects served as controls.


RESULTS
The plasma insulin response to intravenous glucose was reduced in the HNF-1alpha mutation carriers compared to the control subjects, with an area under the curve (median (interquartile range)) of 812 min pmol/l (421, 1647) and 1933 min pmol/l (1521, 2908), respectively (P = 0.03). In striking contrast, the plasma insulin response to tolbutamide was preserved, with an area under the curve of 2109 min pmol/l (1126, 3172) and 2250 min pmol/l (1614, 3276) in the mutation carriers and control subjects, respectively.


CONCLUSIONS
HNF-1alpha mutation carriers are characterized by preserved tolbutamide-induced insulin secretion. Compared to healthy subjects, our MODY3 individuals did not show any increased serum insulin response to tolbutamide, suggesting that HNF-1alpha mutation carriers are not characterized by sulphonylurea hypersensitivity.
Sagen
J V
JV
Section of Paediatrics, Institute of Clinical Medicine, University of Bergen, Bergen, Norway. Jorn.Sagen@pedi.uib.no
Pearson
E R
ER
Johansen
A
A
Spyer
G
G
Søvik
O
O
Pedersen
O
O
Njølstad
P R
PR
Hattersley
A T
AT
Hansen
T
T
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000235:genetics*; D005260:Female; D005951:Glucose Tolerance Test; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000097:blood* / Q000378:metabolism; D000078790:Insulin Secretion; D008297:Male; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics*; D014044:Tolbutamide / Q000494:pharmacology*; D014157:Transcription Factors / Q000235:genetics*
D001786:Blood Glucose; D004268:DNA-Binding Proteins; C496487:HNF1A protein, human; D051538:Hepatocyte Nuclear Factor 1-alpha; D007004:Hypoglycemic Agents; D007328:Insulin; D009687:Nuclear Proteins; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D014044:Tolbutamide