Peroral glucose tolerance test. Relation to skeletal muscle electrolytes

Seventy patients on long-term diuretic therapy for arterial hypertension and/or congestive heart failure were investigated with regard to skeletal muscle electrolytes and the results of a peroral glucose tolerance test. A significant correlation was observed between the muscle content of potassium and the ability to handle a glucose load. Thirty patients underwent a second set of samples six months after the first one, 23 of whom had a reduction of their muscle potassium content relative to the first biopsy. They simultaneously demonstrated a significant impairment of glucose tolerance.     

Fitting and evaluating the glucose curve during a quasi continuous sampled oral glucose tolerance test

A dynamical model for blood glucose concentration, using a quasi continuous sample time interval OGTT is proposed. When this quasi continuous sample OGTT is performed, there are some detectable variations on blood glucose concentrations which could be related with reported endogenous glucose release. It is proposed that blood glucose concentration regulation system can be described by a number of linear, second order, underdamped subsystems, where blood glucose concentration dynamics can be viewed as a multifunction composed by the algebraic sum of the impulse responses of each subsystem, where unit impulse inputs are the glucose load, and the endogenous excitations.     

Meal related glucose monitoring is a method of diagnosing glucose intolerance in pregnancies with high probability of gestational diabetes but normal glucose tolerance by oral glucose tolerance test

Gestational diabetes mellitus diagnosed by classical oral glucose tolerance test can result in fetal complications like macrosomia and polyhydramnios. Guidelines exist on management of patients diagnose by abnormal oral glucose tolerance test with diet modification followed by insulin. Even patients with abnormal oral glucose tolerance test maintaining apparently normal blood sugars with diet are advised insulin if there is accelerated fetal growth. But patients with normal oral glucose tolerance test can present with macrosomia and polyhydramnios. These patients are labelled as not having gestational diabetes mellitus and are followed up with repeat oral glucose tolerance test. We hypothesise that these patients may have an altered placental threshold to glucose or abnormal sensitivity of fetal tissues to glucose. Meal related glucose monitoring in these patients can identify minor abnormalities in glucose disturbance and should be treated to targets similar to physiological levels of glucose in non pregnant adults.     

Plasma androgens and oestradiol during oral glucose tolerance test in patients with polycystic ovaries

Hyperinsulinaemia is common patients with polycystic ovaries (PCO), and a relationship between hyperinsulinaemia and hyperandrogenaemia has been suggested. We studied the effect of increased circulating insulin in response to an oral glucose tolerance test (OGTT) on plasma levels of androgens and oestradiol in PCO patients and in healthy control subjects. A 75 g, 3 h oral glucose tolerance test (OGTT) was performed in eight non-obese and seven obese PCO patients, and in 10 non-obese control subjects. An additional group of five women were fasting during the study period. The increase in insulin concentration was higher in obese and non-obese PCO patients than in non-obese control subjects, and the peak values were observed at 30 or 60 min. In the fasting control subjects, the mean concentration of androstenedione decreased slightly due to a diurnal variation. During the OGTT, mean concentrations of androstenedione decreased in all groups at 30 min, after which a slight increase was observed in PCO patients and a plateau in control subjects. Similarly, mean testosterone increased after an initial decrease in obese PCO patients whereas no change was found in non-obese PCO patients. No statistically significant differences were found in the responses of androstenedione or testosterone levels to OGTT in obese or non-obese PCO patients compared to normals. No significant responses of plasma oestradiol levels to OGTT were found. These findings failed to demonstrate any significantly abnormal acute androgen responses to OGTT-stimulated hyperinsulinaemia in PCO patients, but did not exclude possible long-term effects of hyperinsulinaemia.     

Insulin secretion and sensitivity during oral glucose tolerance test in Korean lean elderly women

Impaired glucose tolerance (IGT) and type 2 diabetes including undiagnosed isolated postchallenge hyperglycemia (IPH) are common in the elderly. The aim of this study was to investigate the insulin secretion and sensitivity in Korean elderly lean diabetic women. Forty-one lean women aged 65-88 years took 2 hr oral glucose tolerance test (OGTT) and were stratified according to the WHO criteria (normal glucose tolerance [NGT], n=20; IGT, n=6; and type 2 diabetics, n=15 including seven IPH). HbA1c and fructosamine progressively increased from the NGT to the diabetic subjects (p=0.006 and p=0.001, respectively). Compared with subjects with NGT, the insulinogenic index, a marker of early insulin secretion and the AUC(ins), a marker of total insulin secretion, decreased significantly in diabetic group [0.53 (-0.44 -1.45) vs. 0.18 (0.00 -1.11), p=0.03 and 306+/-165 vs. 199+/-78 pmol/L, p=0.02 respectively]. A significant difference was found in the AUC(c-peptide) among each group (221+/-59 vs. 206+/-34 vs. 149+/-51 pmol/L, p=0.001 for each). The homeostasis model assessment of insulin resistance (HOMA-IR), a marker of insulin resistance, was not different among the groups. We conclude that compared with NGT subjects, elderly lean women with diabetes have impaired oral glucose-induced insulin secretion but have relatively preserved insulin sensitivity. This suggests that insulin resistance is not necessarily an essential component of Korean elderly lean diabetic women.