Insulin secretory responses in patients with glucose intolerance due to extra-pancreatic causes. Comparison with idiopathic diabetes mellitus

The intravenous xylitol tolerance test in non-lactating cattle

Xylitol is a five-carbon sugar alcohol that is often used for treatment of ketosis in dairy cattle in Japan. An intravenous xylitol tolerance test (IVXTT, 0.1 g/kg, bolus injection through the jugular vein) was performed in 4 non-lactating cows (n = 4) and the results were compared with those of an intravenous glucose tolerance test (IVGTT) performed under equivalent conditions. The serum xylitol concentration reached a peak value (41.4+/-9.0 mg/dl) at 5 min, and then rapidly decreased and almost disappeared within 2 h. The C0 for xylitol was 56.9+/-16.6 mg/dl and the t(1/2) was 8.5+/-0.9 min. The administration of xylitol appeared to cause similar secretion of insulin to that caused by glucose. There was also a reduction in the concentration of free fatty acids. It seems that xylitol has value for the treatment of ketosis. However, rapid administration of xylitol appeared to have an osmotic diuretic action and might be a cause of dehydration.

Insulin secretory response in Japanese type 2 (non-insulin-dependent) diabetic patients

Insulin (immunoreactive insulin, IRI) response during a 100 g oral glucose tolerance test was studied in a large number of patients with definite diabetes, equivocal diabetes, and other pathological states causing glucose intolerance. Definite diabetes was diagnosed in patients with overt fasting hyperglycemia. Once the diagnosis of definite diabetes was made, IRI response remained low after improvement of glucose tolerance. Glucose intolerance caused by other pathological extra-pancreatic conditions was usually accompanied by increased IRI response. IRI response in equivocal diabetes was variable, but almost always decreased in those who developed definite diabetes later. In subjects with a strong family history of type 2 diabetes, the prevalence of a low IRI response was high. In non-diabetic subjects, weight gain caused a marked increase in IRI response and a small increase in blood glucose, while in those who developed diabetes, IRI increased little despite the marked increase in blood glucose. These data suggest that low IRI response is an important feature of type 2 diabetes, perhaps with a hereditary basis in part. It precedes the occurrence of overt hyperglycemia and persists after improvement of glucose tolerance.

Endocrine disorders and diabetes in Japan

The frequency of glucose intolerance including diabetes and IGT in endocrine diseases was compared between Japan and foreign countries. It was revealed that the frequency of diabetes in endocrine diseases is generally higher in Japan than in foreign countries. In addition, plasma insulin response to glucose was exaggerated in Cushing's syndrome with glucose intolerance, but was impaired in acromegaly and pheochromocytoma with glucose intolerance.