Kim C H, Park J Y, Shong Y K, Hong S K, Kim G S, Lee K U
Department of Internal Medicine, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.
Clin Endocrinol (Oxf). 2000 Jan;52(1):87-92. doi: 10.1046/j.1365-2265.2000.00869.x.
Previous studies have demonstrated that endogenous insulin secretion is not suppressed by exogenous insulin in patients with insulinoma. In this study we examined whether insulin secretion in insulinoma patients is suppressed by exogenous insulin during hypoglycaemia.
Sixteen insulinoma patients (5 men and 11 women) and 10 normal subjects were studied. Hyperinsulinaemic glucose clamp studies were performed at both euglycaemia (4.5 mmol/l glucose) and hypoglycaemia (2.5 mmol/l glucose).
In normal subjects, plasma C-peptide levels were suppressed by 66% during the euglycaemic hyperinsulinaemic clamps (P < 0.01). In contrast, in insulinoma patients, plasma C-peptide levels increased by 25% during the clamps (P < 0.05). In the hypoglycaemic hyperinsulinaemic clamps, plasma C-peptide levels were nearly completely (91%) suppressed in normal subjects and partially (39%) suppressed in patients with insulinoma (P < 0.01). The decrease in C-peptide levels during the hypoglycaemic clamps was > 30% in 12 (75%) of 16 insulinoma patients and > 50% in 8 (50%) patients.
This study demonstrated that in patients with insulinoma, insulin secretion was not suppressed by exogenous insulin during euglycaemia but was suppressed during hypoglycaemia, although the degree of suppression was less than that in normal subjects. Our results suggest that the feedback regulation of insulin secretion by exogenous insulin is partially retained in patients with insulinoma.
既往研究表明，胰岛素瘤患者的内源性胰岛素分泌不会被外源性胰岛素抑制。在本研究中，我们检测了低血糖期间外源性胰岛素是否会抑制胰岛素瘤患者的胰岛素分泌。
对16例胰岛素瘤患者（5例男性和11例女性）和10名正常受试者进行了研究。在正常血糖（血糖4.5 mmol/l）和低血糖（血糖2.5 mmol/l）状态下均进行了高胰岛素-正常血糖钳夹试验。
在正常受试者中，正常血糖高胰岛素钳夹试验期间血浆C肽水平被抑制了66%（P < 0.01）。相比之下，在胰岛素瘤患者中，钳夹试验期间血浆C肽水平升高了25%（P < 0.05）。在低血糖高胰岛素钳夹试验中，正常受试者的血浆C肽水平几乎完全被抑制（91%），而胰岛素瘤患者则被部分抑制（39%）（P < 0.01）。16例胰岛素瘤患者中有12例（75%）在低血糖钳夹试验期间C肽水平下降> 30%，8例（50%）患者下降> 50%。
本研究表明，胰岛素瘤患者在正常血糖期间胰岛素分泌不会被外源性胰岛素抑制，但在低血糖期间会被抑制，尽管抑制程度低于正常受试者。我们的结果表明，外源性胰岛素对胰岛素分泌的反馈调节在胰岛素瘤患者中部分保留。
