Search PubMed⌕ Search

Biomedical subjects

C G Fanelli

Publications and source records attributed to C G Fanelli.

23 records · Page 2Linked to original sources
PubMed1996

Impact of recent antecedent hypoglycemia on hypoglycemic cognitive dysfunction in nondiabetic humans.

To test the hypothesis that glycemic thresholds for hypoglycemic cognitive dysfunction, like those for neuroendocrine responses to and symptoms of hypoglycemia, shift to lower plasma glucose concentrations after recent antecedent hypoglycemia, 16 healthy young adult subjects (7 women and 9 men) were studied on two separate occasions in random sequence, once with hyperinsulinemic hypoglycemia (2.6 +/- 0.1 mmol/l, 47 +/- 1 mg/dl) and once with otherwise identical hyperinsulinemic euglycemia (4.8 +/- 0.1 mmol/l, 86 +/- 5 mg/dl) between 1430 and 1630. Neuroendocrine, symptomatic, and cognitive responses to hyperinsulinemic stepped hypoglycemic (4.7, 4.2, 3.6, 3.0, 2.8, 2.5, and 2.2 mmol/l; 85, 75, 65, 55, 50, 45, and 40 mg/dl) clamps were quantitated the following morning on both occasions. Cognitive function tests included measures of information processing (Serial Addition), attention (Stroop Arrow Word), pattern recognition and memory (Delayed Non-Match to Sample), and declarative memory (Paragraph Recall). As expected, plasma glucagon (P = 0.0094), epinephrine (P = 0.0063), and pancreatic polypeptide (P = 0.0046) responses to stepped hypoglycemia were reduced significantly, and symptomatic responses tended to be reduced after afternoon hypoglycemia. Performance on the cognitive function tests deteriorated (P < 0.0001) during stepped hypoglycemic clamps, but there were no significant overall effects of antecedent hypoglycemia on hypoglycemic cognitive dysfunction. Although deterioration was reduced (P < 0.05) from the 2.8 mmol/l (50 mg/dl) to the 2.5 mmol/l (45 mg/dl) steps on the Serial Addition and Delayed Non-Match to Sample tasks after afternoon hypoglycemia, comparable differences were not found on the Stroop Arrow Word or Paragraph Recall tasks. Thus, glycemic thresholds for hypoglycemic cognitive dysfunction, unlike those for neuroendocrine responses to and symptoms of hypoglycemia, do not seem to shift to substantially lower plasma glucose concentrations after recent antecedent hypoglycemia in nondiabetic humans.

Adolescent↗
PubMed1993

Meticulous prevention of hypoglycemia normalizes the glycemic thresholds and magnitude of most of neuroendocrine responses to, symptoms of, and cognitive function during hypoglycemia in intensively treated patients with short-term IDDM.

To test the hypothesis that hypoglycemia unawareness is largely secondary to recurrent therapeutic hypoglycemia in IDDM, we assessed neuroendocrine and symptom responses and cognitive function in 8 patients with short-term IDDM (7 yr) and hypoglycemia unawareness. Patients were assessed during a stepped hypoglycemic clamp, before and after 2 wk and 3 mo of meticulous prevention of hypoglycemia, which resulted in a decreased frequency of hypoglycemia (0.49 +/- 0.05 to 0.045 +/- 0.03 episodes/patient-day) and an increase in HbA1c (5.8 +/- 0.3 to 6.9 +/- 0.2%) (P < 0.05). We also studied 12 nondiabetic volunteer subjects. At baseline, lower than normal symptom and neuroendocrine responses occurred at lower than normal plasma glucose, and cognitive function deteriorated only marginally during hypoglycemia. After 2 wk of hypoglycemia prevention, the magnitude of symptom and neuroendocrine responses (with the exception of glucagon and norepinephrine) nearly normalized, and cognitive function deteriorated at the same glycemic threshold and to the same extent as in nondiabetic volunteer subjects. At 3 mo, the glycemic thresholds of symptom and neuroendocrine responses normalized, and surprisingly, some of the responses of glucagon recovered. We concluded that hypoglycemia unawareness in IDDM is largely reversible and that intensive insulin therapy and a program of intensive education may substantially prevent hypoglycemia and at the same time maintain the glycemic targets of intensive insulin therapy, at least in patients with IDDM of short duration.

Adult↗
PubMed1993

Nocturnal blood glucose control in type I diabetes mellitus.

A major problem in replacing insulin in type I diabetes mellitus is that currently no depot preparation exists that is capable of mimicking the background insulin secretion of the healthy pancreas. Because all of the currently available intermediate- or long-acting insulin preparations have a peaked-action profile, excess insulin action at midnight and insulin waning at dawn occur whenever such an insulin preparation is given at supper time. If the target fasting plasma glucose is the ambitious near-normoglycemia of intensive insulin therapy, intermediate-acting insulin at suppertime easily results in hypoglycemia in the early evening hours and hyperglycemia in the fasting state. The problems of overnight glycemia in type I diabetes are further complicated by the dawn phenomenon and the Somogyi phenomenon. The dawn phenomenon is the combination of an initial decrease in insulin requirements between approximately 2400 and approximately 0300, followed by an increase in the insulin needs between approximately 0500 and approximately 0800. The dawn phenomenon is the result of changes in hepatic (and extrahepatic) insulin sensitivity, which are best attributed to nocturnal growth hormone secretion. The dawn phenomenon is a day-to-day reproducible event that occurs in nearly all diabetic patients. Its contribution to fasting hyperglycemia correlates with diabetes duration (inversely) and the HbA1c percentage (directly). Overall, it is estimated that the specific contribution of the dawn phenomenon to fasting hyperglycemia is approximately 2 mM (approximately 35 mg/dl), but it may be much greater because of the warning of the depot-insulin preparation injected the previous evening. The Somogyi phenomenon, strictly speaking, refers to fasting hyperglycemia that occurs after inducement of nocturnal hypoglycemia by regular insulin. Because the present therapeutic regimens of NPH/Lente insulin given at suppertime cause overnight hyperinsulinemia, excessive fasting hyperglycemia rarely follows nocturnal hypoglycemia, except when excessive glucose is ingested to correct hypoglycemia. However, nocturnal hypoglycemia may easily deteriorate glycemic control later in the day, because it induces prolonged posthypoglycemic insulin resistance, which results in postbreakfast and late-morning hyperglycemia. With nocturnal insulin therapy, it is important to consider the problems of insulin pharmacokinetics, the dawn phenomenon, and the Somogyi phenomenon to prevent both nocturnal hypoglycemia and excessive fasting hyperglycemia.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Glucose↗
PubMed1992

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.

Adult↗