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Glucose-induced hypoglycaemia in insulinoma with impaired glucose tolerance

2003; Elsevier BV; Volume: 361; Issue: 9360 Linguagem: Inglês

10.1016/s0140-6736(03)12694-3

1474-547X

Mitsuo Tashiro, Yasuyuki Kihara, Makoto Otsuki,

Metabolism, Diabetes, and Cancer

Peter Wiesli and colleagues (Nov 9, p 1476)1Wiesli P Spinas GA Pfammatter T Krahenbuhl L Schmid C Glucose-induced hypoglycaemia.Lancet. 2002; 360: 1476Summary Full Text Full Text PDF PubMed Scopus (16) Google Scholar report a case of glucose-induced hypoglycaemia in insulinoma. Other glucose-responsive insulinomas have been reported previously.2Power L A glucose-responsive insulinoma.JAMA. 1969; 207: 893-896Crossref PubMed Scopus (15) Google Scholar, 3Connor H Scarpello JHB An insulinoma presenting with reactive hypoglycemia.Postgrad Med J. 1979; 55: 735-738Crossref PubMed Scopus (23) Google Scholar, 4Sjoberg RJ Kidd GS A glucose-responsive insulinoma—implication for the diagnosis of insulin secreting tumors.Am J Med Sci. 1992; 304: 164-167Crossref PubMed Scopus (13) Google Scholar In those cases, reactive hypoglycaemia was induced by hypersecretion of insulin in response to a meal in patients who were symptom-free during fasting.A 65-year-old man with a 1-year history of lightheadedness after taking lunch was referred to us in 1994. He weighed 75·8 kg on admission, whereas he had been 73 kg for the past several years. He had undergone an oral glucose tolerance test (OGTT) twice in the previous 6 years, both of which showed impaired glucose tolerance, although the concentration of insulin in plasma was not measured. In 1993, he complained of lightheadedness several times per month, which usually occurred 2–3 h after taking lunch, but disappeared after taking a spoonful of sugar.On admission, neurological examination was normal except for orthostatic hypotension. After overnight fasting, mild neuroglycopenic symptoms such as hunger with low capillary blood glucose (2·2–2·8 mmol/L) were evident; these symptoms resolved after taking a spoonful of sugar. A 24 h fast increases neither plasma glucose nor plasma insulin concentrations. Laboratory data were as follows: fasting plasma glucose 2·3 mmol/L; fasting plasma insulin 51 pmol/L; urinary excretion of C-peptide 59·6 nmol/day; ratio of fasting plasma insulin to fasting plasma glucose 0·2. Ingestion of 75 g glucose and injection of 1 mg glucagon increased plasma insulin concentrations, reaching a peak value of 5316 pmol/L at 30 min and 10 380 pmol/L at 15 min, and resulting in severe hypoglycaemia.Abdominal ultrasonography and computed tomography showed a 2·0 cm tumour in the head of the pancreas. The tumour was enucleated surgically, and histology showed an insulinoma with monotonous sheets of small round cells, which were immunostained for insulin. 4 weeks after the operation, an OGTT and intravenous glucagon test were normal. No episode of lightheadedness has occurred for 8 years after the operation. OGTT showed impaired glucose tolerance in 1998.Although several cases of glucose-responsive insulinoma have been reported, it seems to be an unusual presentation. In this case, glucose challenge tests revealed reactive hypoglycaemia, whereas blood glucose did not show severe hypoglycaemia (more than 2·2 mmol/L) when fasting. Furthermore, pre-existing impaired glucose tolerance can mask metabolic features. Peter Wiesli and colleagues (Nov 9, p 1476)1Wiesli P Spinas GA Pfammatter T Krahenbuhl L Schmid C Glucose-induced hypoglycaemia.Lancet. 2002; 360: 1476Summary Full Text Full Text PDF PubMed Scopus (16) Google Scholar report a case of glucose-induced hypoglycaemia in insulinoma. Other glucose-responsive insulinomas have been reported previously.2Power L A glucose-responsive insulinoma.JAMA. 1969; 207: 893-896Crossref PubMed Scopus (15) Google Scholar, 3Connor H Scarpello JHB An insulinoma presenting with reactive hypoglycemia.Postgrad Med J. 1979; 55: 735-738Crossref PubMed Scopus (23) Google Scholar, 4Sjoberg RJ Kidd GS A glucose-responsive insulinoma—implication for the diagnosis of insulin secreting tumors.Am J Med Sci. 1992; 304: 164-167Crossref PubMed Scopus (13) Google Scholar In those cases, reactive hypoglycaemia was induced by hypersecretion of insulin in response to a meal in patients who were symptom-free during fasting. A 65-year-old man with a 1-year history of lightheadedness after taking lunch was referred to us in 1994. He weighed 75·8 kg on admission, whereas he had been 73 kg for the past several years. He had undergone an oral glucose tolerance test (OGTT) twice in the previous 6 years, both of which showed impaired glucose tolerance, although the concentration of insulin in plasma was not measured. In 1993, he complained of lightheadedness several times per month, which usually occurred 2–3 h after taking lunch, but disappeared after taking a spoonful of sugar. On admission, neurological examination was normal except for orthostatic hypotension. After overnight fasting, mild neuroglycopenic symptoms such as hunger with low capillary blood glucose (2·2–2·8 mmol/L) were evident; these symptoms resolved after taking a spoonful of sugar. A 24 h fast increases neither plasma glucose nor plasma insulin concentrations. Laboratory data were as follows: fasting plasma glucose 2·3 mmol/L; fasting plasma insulin 51 pmol/L; urinary excretion of C-peptide 59·6 nmol/day; ratio of fasting plasma insulin to fasting plasma glucose 0·2. Ingestion of 75 g glucose and injection of 1 mg glucagon increased plasma insulin concentrations, reaching a peak value of 5316 pmol/L at 30 min and 10 380 pmol/L at 15 min, and resulting in severe hypoglycaemia. Abdominal ultrasonography and computed tomography showed a 2·0 cm tumour in the head of the pancreas. The tumour was enucleated surgically, and histology showed an insulinoma with monotonous sheets of small round cells, which were immunostained for insulin. 4 weeks after the operation, an OGTT and intravenous glucagon test were normal. No episode of lightheadedness has occurred for 8 years after the operation. OGTT showed impaired glucose tolerance in 1998. Although several cases of glucose-responsive insulinoma have been reported, it seems to be an unusual presentation. In this case, glucose challenge tests revealed reactive hypoglycaemia, whereas blood glucose did not show severe hypoglycaemia (more than 2·2 mmol/L) when fasting. Furthermore, pre-existing impaired glucose tolerance can mask metabolic features.