Reactive hypoglycemia in women. Results of a health survey

Migraine, Brain Glucose Metabolism and the "Neuroenergetic" Hypothesis: A Scoping Review

Increasing evidence suggests that migraine may be the result of an impaired brain glucose metabolism. Several studies have reported brain mitochondrial dysfunction, impaired brain glucose metabolism and gray matter volume reduction in specific brain areas of migraineurs. Furthermore, peripheral insulin resistance, a condition demonstrated in several studies, may extend to the brain, leading to brain insulin resistance. This condition has been proven to downregulate insulin receptors, both in astrocytes and neurons, triggering a reduction in glucose uptake and glycogen synthesis, mainly during high metabolic demand. This scoping review examines the clinical, epidemiologic and pathophysiologic data supporting the hypothesis that abnormalities in brain glucose metabolism may generate a mismatch between the brain's energy reserve and metabolic expenditure, triggering migraine attacks. Moreover, alteration in glucose homeostasis could generate a chronic brain energy deficit promoting migraine chronification. Lastly, insulin resistance may link migraine with its comorbidities, like obesity, depression, cognitive impairment and cerebrovascular diseases. PERSPECTIVE: Although additional experimental studies are needed to support this novel "neuroenergetic" hypothesis, brain insulin resistance in migraineurs may unravel the pathophysiological mechanisms of the disease, explaining the migraine chronification and connecting migraine with comorbidities. Therefore, this hypothesis could elucidate novel potential approaches for migraine treatment.

Hypoglycemia and Islet Dysfunction Following Oral Glucose Tolerance Testing in Pancreatic-Insufficient Cystic Fibrosis

CONTEXT

Oral glucose tolerance test (OGTT)-related hypoglycemia is common in pancreatic-insufficient cystic fibrosis (PI-CF), but its mechanistic underpinnings are yet to be established.

OBJECTIVE

To delineate the mechanism(s) underlying OGTT-related hypoglycemia.

DESIGN AND SETTING

We performed 180-minute OGTTs with frequent blood sampling in adolescents and young adults with PI-CF and compared results with those from a historical healthy control group. Hypoglycemia (Hypo[+]) was defined as plasma glucose <65 mg/dL. We hypothesized that CF-Hypo[+] would demonstrate impaired early phase insulin secretion and persistent late insulin effect compared with control-Hypo[+], and explored the contextual counterregulatory response.

MAIN OUTCOME MEASURE

OGTT 1-hour and nadir glucose, insulin, C-peptide, and insulin secretory rate (ISR) incremental areas under the curve (AUC) between 0 and 30 minutes (early) and between 120 and 180 minutes (late), and Δglucagon120-180min and Δfree fatty acids (FFAs)120-180min were compared between individuals with CF and control participants with Hypo[+].

RESULTS

Hypoglycemia occurred in 15/23 (65%) patients with CF (43% female, aged 24.8 [14.6-30.6] years) and 8/15 (55%) control participants (33% female, aged 26 [21-38] years). The CF-Hypo[+] group versus the control-Hypo[+] group had higher 1-hour glucose (197 ± 49 vs 139 ± 53 mg/dL; P = 0.05) and lower nadir glucose levels (48 ± 7 vs 59 ± 4 mg/dL; P < 0.01), while insulin, C-peptide, and ISR-AUC0-30 min results were lower and insulin and C-peptide, and AUC120-180min results were higher (P < 0.05). Individuals with CF-Hypo[+] had lower Δglucagon120-180min and ΔFFA120-180min compared with the control-Hypo[+] group (P < 0.01).

CONCLUSIONS

OGTT-related hypoglycemia in PI-CF is associated with elevated 1-hour glucose, impaired early phase insulin secretion, higher late insulin exposure, and less increase in glucagon and FFAs. These data suggest that hypoglycemia in CF is a manifestation of islet dysfunction including an impaired counterregulatory response.

Hypoglycemia is common in children with cystic fibrosis and seen predominantly in females

OBJECTIVE

To determine the prevalence of hypoglycemia in children and adolescents with cystic fibrosis (CF) in 2-hour oral glucose tolerance test (OGTT) and continuous glucose monitoring (CGM) under free-living conditions.

RESEARCH DESIGN AND METHODS

Height, weight, body mass index (BMI), hemoglobin A1c (HbA1c), and Forced expiratory volume (FEV1%) were measured in children with CF (aged 5-18 years). Following OGTT, CGM was installed for 3 days. The total hypoglycemic and hyperglycemic time (%) during 3 days was measured. Subjects were categorized according to hypoglycemic time <3% (hypo -) and ≥3% (hypo +). Each category was further divided according to hyperglycemic time <3% (hyper -) or ≥3% (hyper +).

RESULTS

OGTT and CGM were sequentially performed in 45 CF patients. The frequency of hypoglycemia in OGTT and hypoglycemic time ≧3% of CGM were 13.3% and 27.5%, respectively. After 5 cystic fibrosis-related diabetes (CFRD) subjects were excluded, the number of subjects in each subgroup was 17 (hypo-/hyper-), 12 (hypo-/hyper+), 6 (hypo+/hyper-), and 5 (hypo+/hyper+). Significantly higher insulin at 120 minutes was observed in OGTT in (hypo+/hyper-), as compared with subgroup (hypo-/hyper-) (P = .018). Total insulin levels were also significantly higher in (hypo+/hyper-), than (hypo-/hyper-), but were similar to those in the healthy control group (P = .049 and P = .076, respectively). There was a female predominance in hypoglycemic subjects both in OGTT and subgroup (hypo+/hyper-) in the CGM group (P = .033 and P = .033, respectively). FEV1 was significantly lower in hypo + group as a whole, and (hypo+/hyper+) subgroup than in (hypo-/hyper-), (P = .044 and P = .042, respectively); the difference was independent of body mass index-standard deviation score (BMI-SDS) (P = .15 and P = .12, respectively).

CONCLUSION

The frequency of hypoglycemia in children with CF was higher in CGM than that in OGTT. Insulin secretion was delayed and total insulin levels increased in the hypoglycemic patients. Glucose instability/hypoglycemia is associated with poorer lung function in patients with CF, independent of nutritional status.

Plasma glucose thresholds for counterregulation after an oral glucose load

Glucose counterregulation (GCR) plays an important role in the transition between exogenous and endogenous glucose delivery after an oral glucose load. This response is initiated when plasma glucose concentrations are decreased below threshold levels, previously defined in studies of insulin-induced hypoglycemia. In this study, we tested the plasma glucose thresholds for activation of the GCR response under more physiologic circumstances, ie, after glucose ingestion. We studied 20 normal subjects for 300 minutes after 75 g of oral glucose. Between 150 and 300 minutes, blood samples and symptom scores were obtained at 10-minute intervals. After oral glucose, individual glucose nadirs were observed over a wide time range (160 to 290 minutes). Mean glucose concentrations decreased from 5.3 +/- 0.2 mmol/L at 30 minutes before the nadir (-30 minutes) to 3.8 +/- 0.2 mmol/L at the nadir (0 minutes). Mean plasma epinephrine concentrations increased from 210 +/- 35 pmol/L, were significantly elevated at -10 minutes (P < .05), and peaked at +20 minutes (1,008 +/- 184 pmol/L, P < .001). Mean plasma glucagon concentrations were significantly increased over baseline (100%) at +10 minutes (P < .001) and peaked at +30 minutes (122% +/- 7%, P < .001). Seven subjects (out of 15 tested) developed symptoms. Quantitative evaluation revealed a peak in the mean symptom score at +20 minutes, an increase from 0.4 +/- 0.3 to 2.6 +/- 0.1 arbitrary units (P < .06).(ABSTRACT TRUNCATED AT 250 WORDS)

Idiopathic reactive hypoglycemia: a role for glucagon?

We previously reported that patients with idiopathic reactive hypoglycemia (plasma glucose concentration lower than 2.5 mmol/L 2-4 h after the ingestion of 75 g of glucose) display reduced or absent counterregulatory response of the glucagon secretion and increased insulin sensitivity. In order to examine the effect of glucagon on the increased insulin sensitivity in these patients, 12 subjects with idiopathic reactive hypoglycemia underwent a two-step hyperinsulinemic (1 mU/kg.min) euglycemic glucose clamp and were compared with 12 normal control subjects matched for age, weight and sex. During the first step of the glucose clamp (only insulin + glucose infusion) the patients with Idiopathic Reactive Hypoglycemia required higher glucose infusion rates to maintain euglycemia than normal subjects (9.09 +/- 0.29 mg/kg. min vs 7.61 mg/kg.min). When basal glucagon secretion was replaced (+ somatostatin and glucagon, second step of the clamp) the glucose infusion rates required to maintain euglycemia in patients with Idiopathic Reactive Hypoglycemia significantly decreased (to 7.17 +/- 0.40 mg/kg.min) and resulted similar to normal subjects (7.64 +/- 0.41 mg/kg.min). Thus, in patients affected by Idiopathic Reactive Hypoglycemia, glucagon secretion may play an important role in the pathogenesis of the increased insulin sensitivity and hypoglycemia.

Monitoring of blood glucose concentration in subjects with hypoglycaemic symptoms during everyday life

OBJECTIVE

To study the persistence of hypoglycaemic symptoms, changes in blood glucose concentrations, and the relation between reported symptoms and measured blood glucose values in functional hypoglycaemia.

DESIGN

Re-evaluation of symptoms in patients admitted consecutively with suspected hypoglycaemia followed by a case-control study.

SETTING

The Steno Memorial Hospital in Gentofte, Denmark, which specialises in the diagnosis and treatment of and research on endocrine disorders, including hypoglycaemia.

PATIENTS

21 Subjects admitted consecutively with hypoglycaemic symptoms that were relieved by eating in whom insulinoma and other organic disorders presenting with hypoglycaemia had been ruled out. Twelve of these subjects with persistent symptoms entered the case-control study, as did a matched control group.

INTERVENTIONS

Four days of monitoring blood glucose concentrations at home, six daily samples being taken in fixed relation to meals by the finger prick method. Extra samples were taken when symptoms occurred.

MAIN OUTCOME MEASURES

Blood glucose concentration, glycated haemoglobin concentration, and within subject variation in measured values.

RESULTS

After one to three years of observation 19 of the 21 subjects still had symptoms. Six out of 12 subjects experienced hypoglycaemic symptoms during the controlled study. Blood glucose concentration ranged from 3.7 mmol/l to 7.5 mmol/l during these episodes. Changes in blood glucose concentration, mean blood glucose concentrations at each time point, within subject variation in the measured values, and glycated haemoglobin concentration were not significantly different in all patients compared with the control subjects and in patients with symptoms during the study compared with controls.

CONCLUSION

Hypoglycaemic symptoms during everyday life in apparently healthy subjects are persistent but are not related to chemical hypoglycaemia.

Symptomatic reactive hypoglycemia during glucose tolerance test in lithium-treated patients

Glucose, insulin, glucagon, and cortisol responses during a five-hour oral glucose tolerance test (GTT) were evaluated in nine patients with bipolar affective disorders who were receiving lithium treatment and in seven control patients with bipolar affective disorders who were not receiving any treatment. Both the lithium-treated and the control patients were in stable mood at the time of GTT. During GTT mean nadir serum glucose of 48 +/- 2 mg/dL in the lithium-treated patients was significantly lower (P less than 0.001) than mean nadir serum glucose of 62 +/- 2 mg/dL observed in the control subjects. Seven of these nine lithium-treated patients, but none of the control patients, experienced hypoglycemic symptoms coinciding with low serum glucose concentration. In response to hypoglycemia, mean serum cortisol significantly rose (P less than 0.01) to 22 +/- 3 micrograms/dL in the lithium-treated patients, whereas mean serum cortisol levels gradually declined to 10 +/- 2 micrograms/dL in the control patients at 300 minutes. Despite symptomatic postglucose hypoglycemia, plasma glucagon levels in the lithium-treated patients were similar to those observed in the control patients. These findings suggest that chronic lithium treatment is associated with a symptomatic and biochemical hypoglycemia during GTT, which is characterized by a rise in serum cortisol but by lack of appropriate rise in plasma glucagon concentrations.

Premenstrual syndrome

The premenstrual syndrome (PMS) is a major clinical entity afflicting a large segment of the female population. Available information are descriptive in nature and the etiology of this syndrome remains unclear. In this review, both biochemical and psychosocial elements of the syndrome have been explored in an effort to redefine the pathophysiology of this seemingly multifactorial psychoneuroendocrine dysfunction. We propose that luteal phase sensitivity to and subsequent withdrawal from the central effects of the neuropeptides beta-endorphin and alpha-melanocyte-stimulating hormone result in a cascade of neuroendocrine changes within the brain-hypothalamus-pituitary complex. Modulation of neurotransmitter function by these peptides may produce alterations in mood and behavior as well as enhance pituitary release of prolactin and vasopressin. Variable gonadal steroid modulation of these responses from subject to subject likely accounts for the heterogeneous clinical manifestations of the PMS.

Are there recognizable symptoms of abnormal glucose tolerance (hypoglycaemia and hyperglycaemia) in pregnancy

The symptoms noted by 1,291 consecutive patients undergoing a glucose tolerance test during the third trimester of pregnancy were studied to determine whether their presence was attributable to obstetrically important hypoglycaemia or hyperglycaemia. Relevant symptoms were common and, apart from the more frequent occurrence of palpitations in patients with hyperglycaemia, did not have a significant relationship to maternal glucose tolerance patterns. Patients with hypoglycaemia weighed less, but did not evidence a reduced dietary intake, whereas those with hyperglycaemia smoked less. Symptoms classically associated with biochemical hypoglycaemia and hyperglycaemia were not reliable indicators for selection of patients with obstetrically significant hypoglycaemia or hyperglycaemia.

Glucose-insulin interaction in obese individuals with asymptomatic reactive hypoglycemia

The interrelationship of glucose and insulin was investigated in obese nondiabetic subjects with asymptomatic reactive hypoglycemia. Results were compared to those obtained from obese control subjects and normal individuals. The diagnostic criteria for asymptomatic reactive hypoglycemia were the appearance of blood glucose values of 40 mg/dl and below during the postabsorptive phase of a 6-h OGTT and the absence of related symptoms. The blood glucose nadir occurred earlier in obese hypoglycemics than in obese controls. Maximum insulin response was similar in both obese groups, but occurred significantly later in obese hypoglycemics than in obese subjects without hypoglycemia and normal subjects. In obese hypoglycemics the blood glucose nadir was inversely proportional to the time of the insulin peak (i.e. the later the insulin peak the lower the blood glucose nadir) but correlated poorly to maximum insulin values. Delayed insulin response was found to be the major abnormality in asymptomatic reactive hypoglycemia and a probable cause of the decreased ability to maintain post-hyperglycemic glucose homeostasis. Decreased glucose tolerance in some obese hypoglycemics pre-treated with prednisolone suggests that asymptomatic reactive hypoglycemia could be the manifestation of an early diabetic stage.

Lunchtime gin and tonic a cause of reactive hypoglycaemia

10 healthy young subjects drank, on three separate occasions, the equivalent of three gin and tonics containing 50 g alcohol and 60 g sucrose, gin and "Slimline" tonic containing 50 g alcohol and 0.5 g sucrose, or tonic alone containing 60 g sucrose. Their behaviour, symptoms, blood-glucose, and plasma-insulin were monitored for 5 hours. Both of the alcohol-containing drinks caused mild-to-moderate inebriation, but gin and slimline tonic had no significant effect on either blood-glucose or plasma-insulin levels. Gin and tonic provoked a greater insulinaemia and more profound reactive hypoglycaemic response than tonic alone, and in 3 of the subjects this was associated with the appearance of neuroglycopenic symptoms. Alcohol-mediated reactive hypoglycaemia may contribute significantly to motor-car accidents in the late afternoon at a time when blood-alcohol levels have fallen below the legal limit.

Glucose intolerance associated with temporomandibular joint pain-dysfunction syndrome

In order to eliminate any disease process, it is necessary to identify and eliminate etiologic factors associated with the disease process. Reactive hypoglycemia, a common and easily treated disorder, may be a significant factor associated with development of the TMJ syndrome. Five case histories have been presented of patients who exhibited reactive hypoglycemia associated with the TMJ syndrome and who were treated with a combination of occlusal therapy and dietotherapy. Dietotherapy may have reduced the "psychic tension" associated with the TMJ symdrome.

Progressive deterioration of glucose tolerance in the aged

This long-term study of the natural history of glucose tolerance in the aged is now in its eleventh year. Of 411 nondiabetic persons screened on admission to the Jewish Home for the Aged (J.H.A.) since 1968, 15 per cent had abnormally elevated levels of postglucose blood sugar (PGBS) as compared with 25 per cent in the period 1964-1968. Fewer positive reactors were discovered with annual screenings and with the glucose tolerance test (GTT). Although the proportion of positive reactors and of diabetic-type GTT curves was higher in subjects over age 80 than under age 80, there were 83 residents screened annually for five to nine years who retained normal glucose tolerance despite advancing age. The relatively lower rate of deterioration of glucose tolerance in the second period was attributable to: 1) the younger age of residents admitted since 1968, and 2) the diabetes-oriented diet plus emphasis on exercise and prevention of obesity. The reactive hypoglycemia found in 6 per cent of the residents was asymptomatic, whereas iatrogenic hypoglycemia was usually symptomatic and often severe. This led to a deliberate policy of undertreatment. Dietotherapy induced a lasting remission in about 60 per cent of newly diagnosed cases of diabetes, often to the point of normal glucose tolerance. Early diagnosis of chemical diabetes, by postponing or obviating the need for antidiabetic therapy, reduced the incidence of iatrogenic hypoglycemia. Diabetes-oriented measures are recommended for the aged in general, and for residents of homes for the aged in particular.

Obesity: evidence of decreased secretion of glucagon

The increase in concentration of glucagon in plasma caused by infusion of alanine was reduced in obese subjects as compared to that in nonobese control subjects. This was true when the subjects were in the postabsorptive state as well as after an 84-hour fast, at which time the basal glucagon concentration had risen in the nonobese subjects, but remained unaltered in the obese group.