Incidence of severe nocturnal hypoglycemia in patients with type 1 diabetes treated with insulin lispro or regular human insulin in addition to basal insulin glargine.

BACKGROUND AND AIMS: Once-daily (OD) basal insulin glargine (GLA) can be used as part of a multiple daily injection regimen in patients with type 1 diabetes mellitus. This randomized, multicenter study compared GLA+prandial regular human insulin (RHI) with GLA+prandial insulin lispro (LIS) in reducing the incidence of severe nocturnal hypoglycemia at endpoint. In addition, the effects on glycemic control of both treatments were investigated. METHODS AND RESULTS: Patients (489) previously on neutral protamine Hagedorn (NPH) insulin or GLAR plus RHI/LIS were switched to, or continued on GLA (target fasting blood glucose [FBG]=5.0-6.7 mmol/L [90-120 mg/dL]) for 8 weeks (qualification phase) prior to randomization; patients continued with their previous bolus insulin. Patients (n=395) were then randomized to LIS (n=193) or RHI (n=202) and treated for 16 weeks. The proportion of patients experiencing severe nocturnal hypoglycemia at the end of the study was 1.55% (n=3) in the RHI group and 1.11% (n=2) in the LIS group (p=0.938 between groups); the mean difference was 0.44% (95% CI: -1.77, 2.21), suggesting non-inferiority of RHI versus LIS. At the end of the study, both treatments did not differ with respect to glycemic control, as measured by hemoglobin A(1c) and FBG. CONCLUSION: These results suggest that GLA+LIS and GLA+RHI treatments were associated with a similar and low rate of severe nocturnal hypoglycemia. Further studies with greater patient sizes are necessary to verify the findings from the current study.

Brief elevation of hepatic enzymes due to liver ischemia in anorexia nervosa.

Abnormal liver function is occasionally observed in patients affected by anorexia nervosa. Although numerous studies report a strong relation between malnutrition and liver damage, the pathogenesis remains still unclear. We describe a case of a young girl with severe anorexia nervosa who developed acute liver damage with multiorgan involvement during extremely poor nutritional status. In this patient severe malnutrition constituted a predisposing factor for multiorgan dysfunction. In the absence of other identifiable factors, we hypothesized that a marked increase in liver enzymes and other biochemical abnormalities could be a consequence of a precipitating cause as acute hypoperfusion, suggested by clinical symptoms (marked dehydration, hypotension, bradycardia, hypothermia) and laboratory data. Rapid normalization of liver function tests and other biochemical parameters with rehydration and gradual nutritional support confirmed this hypothesis.

Secretive and proliferative tumor profile helps to select the best imaging technique to identify postoperative persistent or relapsing medullary thyroid cancer.

In patients with postoperative persistent medullary thyroid cancer (MTC), the tumor detection rate is generally low for most of the imaging techniques now available. The aim of this study was to investigate if the clinico-biological profile of the tumor may indicate which imaging technique to perform in order to identify postoperative persistent or relapsing MTC foci. Thirty-five consecutive MTC patients with detectable and progressively increasing postoperative serum concentrations of calcitonin were enrolled in the study. The detection rates of 18F-deoxy-d-glucose (FDG)-positron emission tomography (PET), somatostatin receptor scintigraphy (SRS), and 131I-metaiodobenzylguanidine scintigraphy (MIBG) were compared in relation with calcitonin and carcinoembryonic antigen serum concentrations, Ki-67 score and results of conventional imaging techniques (CIT). FDG-PET positivity was significantly associated with calcitonin serum concentrations >400 pg/ml and Ki-67 score >2.0% (P<0.05), while SRS positivity was associated with calcitonin serum concentrations >800 pg/ml (P<0.05). SRS positivity significantly correlated with tumor appearance at CIT (P<0.01), while FDG-PET was positive in nine CIT-negative patients. The secretive and proliferative tumor profile may guide the choice of the imaging technique to use in the follow-up of patients with MTC. A Ki-67 score >2.0% suggests to perform a FDG-PET in addition to conventional imaging. Calcitonin secretion predicts both FDG-PET and SRS uptake but SRS positivity is generally found only in patients with well defined MTC lesions that are also detectable at the conventional imaging examination. MIBG outcome is not predicted by any clinico-biological factors here investigated.

The biological characterization of neuroendocrine tumors: the role of neuroendocrine markers.

Neuroendocrine tumors (NET) may originate in different organs, from cells embryologically different but expressing common phenotypic characteristics, such as: the immuno-reactivity for markers of neuroendocrine differentiation (defined as "pan-neuroendocrine"), the capacity to secrete specific or aspecific peptide and hormones and the expression of some receptors, that are at the basis of the current diagnostic and therapeutical approach, peculiar to these tumors. NET have been conventionally distinguished in functioning, when associated with a recognized clinical endocrine syndrome, and non-functioning. However, this terminology may be misleading, since the great majority of NET may secrete neuroendocrine peptides, which can be employed as clinical markers for both diagnosis and follow-up. On the other hand, tissue immuno-reactivity for specific hormones does not always reflect secretory activity of the tumor cells. Finally, receptors and genetic markers are acquiring a relevant role in the characterization of NET, both improving knowledge of biology and physiopathology of NET, as well as in developing specific strategies to establish an early diagnosis and targeted therapies, to adopt prophylactic strategies in familial forms, and to identify more efficacious targets for therapy in the future.

Biochemical and molecular characterization of the novel BRAF(V599Ins) mutation detected in a classic papillary thyroid carcinoma.

Activating mutations of the BRAF gene are the most common genetic alterations in papillary thyroid carcinomas (PTCs) and the T1799A transversion, resulting in BRAFV600E, appeared virtually unique in this cancer type. Here, we report on the identification in a classic PTC of a novel BRAF mutation, namely a 1795GTT insertion, resulting in BRAFV599Ins, and describe its biochemical and molecular characterization. Kinase assays carried out on BRAFV599Ins and BRAFV600E revealed a three- to five-fold increase in the enzymatic activity of both mutants with respect to BRAFWT. Similarly, evaluation of BRAF-induced phosphorylation of MEK, MAPK and RSK revealed a significant MAPK cascade activation in cells expressing BRAFV599Ins or BRAFV600E, but not in cells expressing BRAFWT. Molecular dynamic simulations showed a destabilization of the inactive conformation of the enzyme in both BRAFV599Ins and BRAFV600E mutants, but not in BRAFWT. The analysis of the interaction energies inside the catalytic site allowed to demonstrate the presence of repulsive electrostatic forces acting on the activation loop and moving from inward to outward of the mutant enzymes. Finally, focus assays in NIH-3T3 cells confirmed a high transformation rate in the cells transfected either with BRAFV599Ins or BRAFV600E. In conclusion, this study demonstrated that BRAFV599Ins, as BRAFV600E, is a 'gain of function' mutation, characterized by a constitutive catalytic activation, which accounts for its causative role in the studied PTC.

Suppressive effect of secretin upon pancreatic alpha cell function.

Highly purified secretin, infused endoportally in five conscious mongrel dogs at a rate of 10 clinical units per min for 20 min, caused a prompt and statistically significant reduction in the pancreaticoduodenal vein level of pancreatic glucagon from a control average of 1130 pg/ml (SEM+/-312) to a nadir of 492 pg/ml (SEM+/-194) 15 min later (P < 0.01). During modest hyperglycemia of about 130 mg/100 ml, induced by glucose infusion, the infusion of secretin at the same rate elicited even more dramatic suppression of pancreaticoduodenal glucagon levels to virtually unmeasurable concentrations. At a lower rate of infusion (5 U priming injection followed by 1 U/min for 20 min) significant suppression of glucagon secretion during hyperglycemia was also observed. Stimulation of endogenous secretin release by the intraduodenal administration of 14 mEq of HCl in 10 dogs during intravenous glucose infusion was followed by a decline in pancreaticoduodenal vein glucagon from 130 pg/ml (SEM+/-34) to a nadir of 99 pg/ml (SEM+/-32) 5 min later (P < 0.05). The infusion of secretin at a rate of 10 U/min in alloxan-diabetic dogs was associated with a significant decline in peripheral venous plasma glucagon, from a mean preinfusion level of 272 pg/ml (SEM+/-39) to a nadir of 128 pg/ml (SEM+/-22) (P < 0.01). It was concluded that exogenous secretin in the doses employed in this study is a potent suppressor of glucagon secretion, particularly during hyperglycemia. HCl-stimulated endogenous secretin also suppresses glucagon secretion. The ability of secretin to augment the glucagon-suppressing effect of ingested glucose qualifies it uniquely for a physiologic role as a modifier of the islet cell response to ingested glucose. The fact that it lowers the hyperglucagonemia of alloxan-diabetic dogs suggests that its glucagon-suppressing activity may not be insulin dependent.

Adrenergic mechanisms contribute to the late phase of hypoglycemic glucose counterregulation in humans by stimulating lipolysis.

Three studies were performed on nine normal volunteers to assess whether catecholamine-mediated lipolysis contributes to counterregulation to hypoglycemia. In these three studies, insulin was intravenously infused for 8 h (0.30 mU.kg-1.min-1 from 0 to 180 min, and 0.40 mU.kg-1.min-1 until 480 min). In study I (control study), only insulin was infused; in study II (direct + indirect effects of catecholamines), propranolol and phentolamine were superimposed to insulin and exogenous glucose was infused to reproduce the same plasma glucose (PG) concentration of study I. Study III (indirect effect of catecholamines) was the same as study II, except heparin (0.2 U.kg-1.min-1 after 80 min), 10% Intralipid (1 ml.min-1 after 160 min) and variable glucose to match PG of study II, were also infused. Glucose production (HGO), glucose utilization (Rd) [3-3H]glucose, and glucose oxidation and lipid oxidation (LO) (indirect calorimetry) were determined. In all three studies, PG decreased from approximately 4.8 to approximately 2.9 mmol/liter (P = NS between studies), and plasma glycerol and FFA decreased to a nadir at 120 min. Afterwards, in study I plasma glycerol and FFA increased by approximately 75% at 480 min, but in study II they remained approximately 40% lower than in study I, whereas in study III they rebounded as in study I (P = NS). In study II, LO was lower than in study I (1.69 +/- 0.13 vs. 3.53 +/- 0.19 mumol.kg-1.min-1, P less than 0.05); HGO was also lower between 60 and 480 min (7.48 +/- 0.57 vs. 11.6 +/- 0.35 mumol.kg-1.min-1, P less than 0.05), whereas Rd was greater between 210 and 480 min (19 +/- 0.38 vs. 11.4 +/- 0.34 mumol.kg-1.min-1, respectively, P less than 0.05). In study III, LO increased to the values of study I; between 4 and 8 h, HGO increased by approximately 2.5 mumol.kg-1.min-1, and Rd decreased by approximately 7 mumol.kg-1.min-1 vs. study II. We conclude that, in a late phase of hypoglycemia, the indirect effects of catecholamines (lipolysis mediated) account for at least approximately 50% of the adrenergic contribution to increased HGO, and approximately 85% of suppressed Rd.

Mechanisms of glucagon secretion during insulin-induced hypoglycemia in man. Role of the beta cell and arterial hyperinsulinemia.

To elucidate the mechanisms controlling the response of glucagon to hypoglycemia, a vital component of the counterregulatory hormonal response, the role of intraislet insulin was studied in seven normal subjects and five subjects with insulin-dependent diabetes mellitus (IDDM) (of less than 15-mo duration). In the normal subjects, hypoglycemia (arterial plasma glucose [PG] 53 +/- 3 mg/dl) induced by an intravenous insulin infusion (30 mU/m2 X min for 1 h, free immunoreactive insulin [FIRI] 58 +/- 2 microU/ml) elicited a 100% fall in insulin secretion and an integrated rise in glucagon of 7.5 ng/ml per 120 min. When endogenous insulin secretion was suppressed by congruent to 50 or congruent to 85% by a hyperinsulinemic-euglycemic clamp (FIRI 63 +/- 1.5 or 147 +/- 0.3 microU/ml, respectively) before hypoglycemia, the alpha cell responses to hypoglycemia were identical to those of the control study. When the endogenous insulin secretion was stimulated by congruent to 100% (hyperinsulinemic-hyperglycemic clamp, FIRI 145 +/- 1.5 microU/ml, PG 132 +/- 2 mg/dl) before hypoglycemia, the alpha cell responses to the hypoglycemia were also superimposable on those of the control study. Finally, in C-peptide negative diabetic subjects made euglycemic by a continuous overnight intravenous insulin infusion, the alpha cell responses to hypoglycemia were comparable to those of normal subjects despite absent beta cell secretion, and were not affected by antecedent hyperinsulinemia (hyperinsulinemic-euglycemic clamp for 2 h, FIRI 61 +/- 2 microU/ml). These results indicate that the glucagon response to insulin-induced hypoglycemia is independent of the level of both endogenous intraislet and exogenous arterial insulin concentration in normal man, and that this response may be normal in the absence of endogenous insulin secretion, in contrast to earlier reports. Thus, loss of beta cell function is not responsible for alpha cell failure during insulin-induced hypoglycemia in IDDM.

Modest decrements in plasma glucose concentration cause early impairment in cognitive function and later activation of glucose counterregulation in the absence of hypoglycemic symptoms in normal man.

To establish the glycemic threshold for onset of neuroglycopenia (impaired cognitive function, measured by the latency of the P300 wave), activation of hormonal counterregulation and hypoglycemic symptoms, 12 normal subjects were studied either under conditions of insulin-induced, glucose-controlled plasma glucose decrements, or during maintenance of euglycemia. A decrement in plasma glucose concentration from 88 +/- 3 to 80 +/- 1 mg/dl for 150 min did not result in changes in the latency of the P300 wave nor in an activation of counterregulatory hormonal response. In contrast, a greater decrement in plasma glucose concentration from 87 +/- 3 to 72 +/- 1 mg/dl for 120 min caused an increase in the latency of the P300 wave (from 301 +/- 12 to 348 +/- 20 ms, P less than 0.01), a subsequent increase in all counterregulatory hormones but no hypoglycemic symptoms. Finally, when plasma glucose concentration was decreased in a stepwise manner from 88 +/- 2 to 50 +/- 1 mg/dl within 75 min, the increase in the latency of the P300 wave was correlated with the corresponding plasma glucose concentration (r = -0.76, P less than 0.001). The glycemic threshold for hypoglycemic symptoms was 49 +/- 2 mg/dl. Thus, in normal man the glycemic threshold for neuroglycopenia (72 +/- 1 mg/dl) is greater than currently thought; the hormonal counterregulation follows the onset of neuroglycopenia; the hypoglycemic symptoms are a late indicator of advanced neuroglycopenia.

Ethanol impairs post-prandial hepatic protein metabolism.

The effects of acute ethanol ingestion on whole body and hepatic protein metabolism in humans are not known. To simulate social drinking, we compared the effects of the association of a mixed meal (632 kcal, 17% amino acids, 50% glucose, 33% lipids) with a bottle of either table wine (ethanol content 71 g) or water on the estimates ([1-14C]-leucine infusion) of whole body protein breakdown, oxidation, and synthesis, and on the intravascular fractional secretory rates (FSR) of hepatically (albumin, fibrinogen) and extrahepatically (IgG) synthesized plasma proteins in two randomized groups (ethanol n = 7, water n = 7) of healthy nonalcoholic volunteers. Each study was carried out for 8 h. Protein kinetics were measured in the overnight post-absorptive state, over the first 4 h, and during a meal infusion (via a nasogastric feeding tube at constant rate) combined with the oral ingestion of wine or water, over the last 4 h. When compared with water, wine ingestion during the meal reduced (P < 0.03) by 24% the rate of leucine oxidation, did not modify the estimates of whole body protein breakdown and synthesis, reduced (P < 0.01) by approximately 30% the FSR of albumin and fibrinogen, but did not affect IgG FSR. In conclusion, 70 g of ethanol, an amount usual among social drinkers, impairs hepatic protein metabolism. The habitual consumption of such amounts by reducing the synthesis and/or secretion of hepatic proteins might lead to the progressive development of liver injury and to hypoalbuminemia also in the absence of protein malnutrition.

Correlation between B-RAFV600E mutation and clinico-pathologic parameters in papillary thyroid carcinoma: data from a multicentric Italian study and review of the literature.

Recently, a somatic point mutation of the B-RAF gene (V600E) has been identified as the most common genetic event in papillary thyroid carcinoma (PTC), with a prevalence variable among different series. Since discordant data on the clinico-pathologic features of B-RAF mutated PTC are present in the literature, the aim of the present co-operative study was to establish the prevalence of this genetic alteration and to perform a genotype-phenotype correlation in a large cohort of patients with PTC. To this purpose, a series of 260 sporadic PTCs with different histological variants were included in the study. The mutational analysis of the B-RAF gene was performed either by RT-PCR followed by single-stranded conformational polymorphism or by PCR and direct sequencing. Statistical analyses were obtained by means of chi2/Fisher's exact test and t-test. Overall, a heterozygous T > A transversion at nucleotide 1799 (V600E) was found in 99 out of 260 PTCs (38%). According to the histological type of the tumor, the B-RAF (V600E) mutation was present in 48.3% of cases of classic PTCs (85 out of 176), in 17.6% (nine out of 51) of follicular variants of PTCs, in 21.7% (five out of 23) in other PTC variants and in none of the ten poorly differentiated tumors. B-RAF (V600E) was significantly associated with the classic variant of PTC (P = 0.0001) and with an older age at diagnosis (P = 0.01). No statistically significant correlation was found among the presence of B-RAF (V600E) and gender, tumor node metastasis (TNM), multicentricity of the tumor, stage at diagnosis and outcome. In conclusion, the present study reports the prevalence of B-RAF (V600E) (38%) in the largest series of sporadic PTCs, including 260 cases from three different Italian referring centers. This prevalence is similar to that calculated by pooling together all data previously reported, 39.6% (759 out of 1914 cases), thus indicating that the prevalence of this genetic event lies around 38-40%. Furthermore, B-RAF (V600E) was confirmed to be associated with the papillary growth pattern, but not with poorer differentiated PTC variants. A significant association of B-RAF mutation was also found with an older age at diagnosis, the mutation being very rare in childhood and adolescent PTCs. Finally, no correlation was found with a poorer prognosis and a worse outcome after a median follow-up of 72 months.

Evaluation of goiter using ultrasound criteria: a survey in a middle schoolchildren population of a mountain area in Central Italy.

Iodine deficiency is still an important health care problem in the world. In Italy, as in most European countries, it is responsible for the development of mild to moderate endemic goiter. In 1995 we conducted a goiter survey in the Gubbio township, an area of Umbria region in Italy, close to the Appenine mountain chain. This study demonstrated a high prevalence of goiter in the middle schoolchildren population, indicating the presence of moderate endemic goiter. Soon after, a goiter prevention campaign aimed at implementing the consumption of iodinated salt was started. In 2001, a second survey was conducted in the middle schoolchildren (age 11-14 yr old) of Gubbio and neighbour townships. Eight hundred thirteen subjects were studied. Data obtained in 240 age-matched children, studied in the same area in 1995, were used for comparison to monitor changes 5 yr after the beginning of iodine prophylaxis. Thyroid volume was measured by ultrasonography. Gland volume was expressed in ml. A large population living in a iodine-sufficient area, previously reported by others, was used as control. Urinary iodine excretion was measured randomly in 20% of the children. The overall prevalence of goiter decreased between 1995 and 2001 from 29 to 8%. Goiter odds ratio (OR), corrected for age, was 4.0 (95% CI 2.8-5.9) for 1995 compared to 2001 (p<0.000). Mean thyroid volume in the matched populations was 7.6+/-2.5 ml in 1995 and 5.7+/-2.1 ml in 2001. Median iodine urinary excretion increased from 72.6 to 93.5 mug/l, at the limit of statistical significance. Living in a rural area, no consumption of iodized salt and familiarity for goiter represented independent risk factors for goiter development. This study was the first conducted in Umbria region and confirmed that an implementation campaign for iodized salt consumption is a simple and useful instrument to prevent endemic goiter and related diseases. A new survey to evaluate goiter prevalence in the same area 10 yr after the beginning of iodine prophylaxis is already planned.

A randomized controlled trial to evaluate the efficacy of ultrasound-guided laser photocoagulation for treatment of benign thyroid nodules.

This randomized controlled study was designed to test the efficacy and safety of percutaneous ultrasound (US)-guided laser photocoagulation (PLP) for treatment of subjects with compressive symptoms due to benign thyroid nodules and/or at high surgical risk. Twenty six subjects were randomized to the intervention (no. 13, age 68+/-3 yr, mean+/-SEM) or observation (no. 13, age 71+/-2 yr) groups. In the control group, the volume of nodules did not significantly change over the 30 week period of observation. In the intervention group, median nodule volume at baseline was 8.2 ml (range 2.8-26.9) and was not significantly different from that of the control group. Nodules decreased significantly (p<0.0001) by 22% after 2 weeks (6.5 ml; range 2.4-16.7) and by 44% after 30 weeks (4.6 ml; range 0.69-14.2). Energy given was correlated (p<0.05) with the reduction of thyroid nodule volume. All patients tolerated the treatment well and reported relief from compressive and cosmetic complaints (p<0.05). At the time of enrolment 7/13 (54%) and 6/13 (46%) of patients in the intervention and control groups, respectively, had sub clinical hyperthyroidism. PLP normalized thyroid function at 6 and 30 weeks after treatment. In conclusion, PLP is a promising safe and effective procedure for treatment of benign thyroid nodules in patients at high surgical risk.

Circulating insulin and insulin growth factor-1 are independent determinants of left ventricular mass and geometry in essential hypertension.

BACKGROUND: It is unclear whether insulin and insulin-like growth factor-1 (IGF-1) are independent determinants of left ventricular (LV) mass in essential hypertension. METHODS AND RESULTS: We studied 101 never-treated nondiabetic subjects with essential hypertension. All had 24-hour noninvasive ambulatory blood pressure (ABP) monitoring and a 75-g oral glucose tolerance test. We determined fasting glucose, insulin, and IGF-1 and postload glucose and insulin 2 hours after glucose. Insulin resistance was estimated by the homeostasis model assessment (HOMA(IR)) formula. LV mass showed an association with body mass index (BMI) (r=0.47; P<0.01), postload insulin (r=0.54; P<0.01), HOMA(IR) (r=0.39; P<0.01), and IGF-1 (r=0. 43; P<0.01) and a weaker association with average 24-hour systolic and diastolic ABPs (r=0.29 and r=0.26; P<0.05) and basal insulin (r=0.31; P<0.05). Relative wall thickness was positively related to IGF-1 (r=0.39; P<0.01) but not to fasting or 2-hour postload insulin, HOMA(IR), and glucose. In a multiple regression analysis, the final LV mass model (R(2)=0.64) included IGF-1, postload insulin, average 24-hour systolic ABP, sex, and BMI. IGF-1 and postload insulin accounted for >40% of variability of LV mass. The final model (R(2)=0.36) for relative wall thickness included IGF-1 (16% total explained variability), average 24-hour systolic ABP, sex, BMI, and age but not insulin and HOMA(IR). CONCLUSIONS: These data indicate that insulin and IGF-1 are powerful independent determinants of LV mass and geometry in untreated subjects with essential hypertension and normal glucose tolerance.

Thymic neuroendocrine carcinoma (carcinoid) in multiple endocrine neoplasia type 1 syndrome: the Italian series.

Neuroendocrine tumors may occur in the setting of multiple endocrine neoplasia type 1 (MEN1) syndrome. Among these, a probably underestimated prevalence of well differentiated neuroendocrine thymic carcinoma (carcinoid), a neoplasm characterized by very aggressive behavior, has been described. We report characterization of the seven Italian cases in which this association occurred among a series of 221 MEN1 patients (41 sporadic and 180 familial cases; prevalence, 3.1%). All of the patients were male, and six of seven (85%) were heavy smokers. No associated hormonal hypersecretion was detected. The first diagnosis was between the second and fifth decades. Familial clusters were present in three of seven (42.8%). No genotype-phenotype correlation was found. All seven cases were associated with hyperparathyroidism. In one patient, prophylactic thymectomy revealed a small nodular lesion suggestive of a thymic carcinoid, providing evidence that preventive thymectomy might prevent additional growth of an occult thymic carcinoid. These findings confirm that thymic carcinoids are associated with a very high lethality, with a near-total prevalence in smoker males. Therefore, prophylactic thymectomy should be considered at neck surgery for primary hyperparathyroidism in MEN1 male patients, especially for smokers, and, due to the frequent familial clusters distribution of this pathology, in subjects with affected relatives presenting this feature. Thus, we recommend screening every patient affected with a neuroendocrine thymic neoplasm for MEN1 syndrome.

HbA1 in subjects with abnormal glucose tolerance but normal fasting plasma glucose.

HbA1(a+b+c)(HbA1) was determined chromatographically in 107 subjects with normal fasting plasma glucose (FPG) and 112 patients with overt diabetes. Subjects with normal FPG were divided into two groups based on their response to two oral glucose tolerance tests (OGTTs), at an interval of 2 mo. In 40 subjects with normal OGTT (group I), HbA1 ranged from 5.2% to 7.2%, while in 67 subjects with abnormal OGTT (group II), it ranged from 6.3% to 9.6%. HbA1 levels were significantly higher in group II than in group I (7.7 +/- 0.09% versus 6.4 +/- 0.08%, mean +/- SEM, P less than 0.0005), but 14 subjects of group II had HbA1 levels less than 7.2%. No correlation was found between HbA1 and FPG, OGTT peak, and curve area in either group. However, the correlation became significant in all 107 subjects with normal FPG (groups I + II). In patients with overt diabetes, HbA1 ranged from 6.3% to 18% (11.9 +/- 0.22%) and correlated with FPG (r = 0.78, P less than 0.0005). The traditional OGTT seems more sensitive than the HbA1 measurement in detecting subjects with reduced carbohydrate tolerance. HbA1 level, on the other hand, is known to be more specific indicator of structural abnormalities following long-term hyperglycemia. Thus HbA1 determination might be a helpful test along with OGTT to improve both selection and follow-up subjects with true borderline diabetes.

Important role of adrenergic mechanisms in acute glucose counterregulation following insulin-induced hypoglycemia in type I diabetes. Evidence for an effect mediated by beta-adrenoreceptors.

UNLABELLED: During hypoglycemia induced by an i.v. insulin infusion for 60 min, rates of plasma glucose (PG) decrease and recovery, PG nadir, and plasma counter-regulatory hormone and free fatty acid responses were studied in eight type I uncomplicated diabetic subjects and eight nondiabetic subjects. Each subject was tested three times at two different rates of insulin infusion (25 and 32 mU/m2/min): (1) during infusion of saline, (2) during infusion of phentolamine + propranolol (combined alpha, beta-blockade), and (3) during infusion of propranolol alone (isolated beta-blockade) for 150 min. At the time of the studies, the diabetic subjects had been made euglycemic by an overnight i.v. insulin infusion. During infusion of insulin (25 mU/m2/min) and saline, the rates of PG decrease and recovery were slower (P less than 0.01) and PG nadir was delayed in the diabetic subjects. Moreover, their plasma glucagon response was blunted while plasma epinephrine, norepinephrine, growth hormone, and cortisol responses were similar in both groups. Infusion of insulin at 32 mU/m2/min caused larger decreases in PG than had been observed when insulin was infused at 25 mU/m2/min. Plasma glucagon responses increased in the nondiabetic subjects (P less than 0.05) but not in the diabetic subjects. However, in the diabetic subjects, plasma epinephrine increased more than in the nondiabetic subjects (P less than 0.05). There was an inverse correlation between the individual plasma epinephrine responses and the plasma glucagon responses in the diabetic subjects (r = -0.72) but not in the nondiabetic subjects. Alpha, beta-adrenergic blockade decreased the plasma glucose nadir and impaired the rate at which normoglycemia was restored in the diabetic subjects (P less than 0.005 vs. saline) but not in the nondiabetic subjects. Plasma catecholamine and growth hormone responses were increased and plasma FFA recovery was suppressed in both groups (P less than 0.05 vs. saline), while the cortisol responses were unaltered. During isolated beta-adrenergic blockade, changes in plasma glucose, counterregulatory hormones and FFA were essentially identical to those observed during combined alpha, beta-adrenergic blockade in both groups except that the augmented plasma norepinephrine responses were no longer apparent. CONCLUSIONS: although epinephrine is not essential for prompt restoration of normoglycemia in normal man following insulin-induced hypoglycemia, it plays a major role in glucose counterregulation in diabetics who have an impaired glucagon secretion in response to hypoglycemia. These counterregulatory effects of epinephrine are mediated by beta-adrenoreceptors.

Acute antihyperglycemic mechanisms of metformin in NIDDM. Evidence for suppression of lipid oxidation and hepatic glucose production.

To establish the antihyperglycemic mechanisms of metformin in non-insulin-dependent diabetes mellitus (NIDDM) independently of the long-term, aspecific effects of removal of glucotoxicity, 21 NIDDM subjects (14 obese, 7 nonobese) were studied on two separate occasions, with an isoglycemic (plasma glucose approximately 9 mM) hyperinsulinemic (two-step insulin infusion, 2 h each, at the rate of 4 and 40 mU.m-2.min-1) clamp combined with [3-3H]glucose infusion and indirect calorimetry, after administration of either metformin (500 mg per os, at -5 and -1 h before the clamp) or placebo. Compared with placebo, hepatic glucose production (HGP) decreased approximately 30% more after metformin (from 469 +/- 50 to 330 +/- 54 mumol/min), but glucose uptake did not increase. Metformin suppressed free fatty acids (FFAs) by approximately 17% (from 0.42 +/- 0.04 to 0.35 +/- 0.04 mM) and lipid oxidation by approximately 25% (from 4.5 +/- 0.4 to 3.4 +/- 0.4 mumol.kg-1.min-1) and increased glucose oxidation by approximately 16% (from 16.2 +/- 1.4 to 19.3 +/- 1.3 mumol.kg-1.min-1) compared with placebo (P < 0.05), but did not affect nonoxidative glucose metabolism, protein oxidation, or total energy expenditure. Suppression of FFA and lipid oxidation after metformin correlated with suppression of HGP (r = 0.70 and r = 0.51, P < 0.001). The effects of metformin in obese and nonobese subjects were no different. We conclude that the specific, antihyperglycemic effects of metformin in the clinical condition of hyperglycemia in NIDDM are primarily due to suppression of HGP, not stimulation of glucose uptake, and are mediated, at least in part, by suppression of FFA and lipid oxidation.

Evidence of increased systemic glucose production and gluconeogenesis in an early stage of NIDDM.

To assess the mechanisms of fasting hyperglycemia in NIDDM patients with mild elevation of fasting plasma glucose (FPG) compared with NIDDM patients with overt hyperglycemia, we studied 29 patients with NIDDM, who were divided in two groups according to their fasting plasma glucose (<7.8 and > or =7.8 mmol/l for groups A and B, respectively), and 16 control subjects who were matched with NIDDM patients for age, sex, and body mass index. All subjects were infused with [3-3H]glucose between 10:00 P.M. and 10:00 A.M. during overnight fasting to determine glucose fluxes. In 27 subjects (17 diabetic and 10 control), [U-14C]alanine was simultaneously infused between 4:00 A.M. and 10:00 A.M. to measure gluconeogenesis (GNG) from alanine. Arterialized-venous plasma samples were collected every 30 min for measurement of glucose fluxes, GNG, and glucoregulatory hormones. In group A, plasma glucose, rate of systemic glucose production (SGP), and GNG were greater than in control subjects (7.2 +/- 0.2 vs. 4.9 +/- 0.1 mmol/l, 10.9 +/- 0.2 vs. 9.5 +/- 0.3 micromol x kg(-1) x min(-1), and 0.58 +/- 0.04 vs. 0.37 +/- 0.02 micromol x kg(-1) x min(-1), respectively, for group A and control subjects; mean value 8:00 A.M.-10:00 A.M., all P < 0.05). Both increased SGP and GNG correlated with plasma glucose in all subjects (r = 0.77 and r = 0.75, respectively, P < 0.005). Plasma counterregulatory hormones did not differ in NIDDM patients compared to control subjects. The present studies demonstrate that SGP and GNG are increased in NIDDM patients without overt fasting hyperglycemia. Thus these metabolic abnormalities primarily contribute to early development of overnight and fasting hyperglycemia in NIDDM.

The adrenergic contribution to glucose counterregulation in type I diabetes mellitus. Dependency on A-cell function and mediation through beta 2-adrenergic receptors.

In order to assess the adrenergic contribution to hypoglycemic glucose counterregulation in type I diabetes mellitus and to determine whether the adrenergic contribution is mediated through beta 1- or beta 2-adrenergic receptors, hypoglycemia was induced by an i.v. insulin infusion (30 mU/m2 x min) for 60 min in 11 insulin-dependent diabetic patients (IDDM), 5 with normal plasma glucagon responses and 6 with blunted responses, and also in 7 age-weight-matched nondiabetic subjects. Rates of plasma glucose decrease and postnadir increase, as well as plasma concentrations of free insulin and of counterregulatory hormones, were measured when insulin was infused alone, and when insulin was infused along with propranolol (a beta 1- and beta 2-adrenergic receptor antagonist) or metoprolol (a selective beta 1-antagonist). Postnadir plasma glucose recovery was decreased in IDDM with blunted plasma glucagon responses (21 +/- 0.8 mumol x L-1 x min-1, P less than 0.001), but was normal in patients with normal plasma glucagon responses (30 +/- 0.4 versus 33 +/- 0.5 mumol x L-1 x min-1 in nondiabetic subjects, P = NS). Postnadir plasma glucose recovery was not affected by either propranolol or metoprolol in normal subjects and in IDDM with normal glucagon responses. However, in IDDM with blunted plasma glucagon responses, postnadir plasma glucose recovery was further decreased by propranolol (14 +/- 0.6 mumol x L-1 x min-1, P less than 0.01), but was unaffected by metoprolol (22 +/- 0.9 mumol x L-1 x min-1, P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)