Hypoglycemia unawareness in IDDM.
ABSTRACT To assess the characteristics of patients with hypoglycemia unawareness (development of neuroglycopenia without appropriate prior autonomic warning symptoms) and its predisposing factors.
We studied 43 insulin-dependent diabetes mellitus patients who were objectively categorized as having or not having hypoglycemia using the stepped hypoglycemic clamp technique in which plasma glucose was clamped at plateaus of 4.3, 3.6, 3.0, and 2.3 mmol/l and a statistical criterion (onset of autonomic warning symptoms at a plasma glucose concentration 2 SD below normal) and examined their clinical characteristics and hormonal, symptomatic, and cognitive responses.
Eleven (26%) of the patients were classified as having hypoglycemia unawareness. Compared with the other patients, unaware patients had a lower HbA1c level (P < 0.01), a longer duration of diabetes (P < 0.01), and a history of more severe hypoglycemia (P < 0.003). During experimental hypoglycemia, counterregulatory hormone responses, neuroglycopenic symptoms, and cognitive dysfunction all began at lower plasma glucose concentrations in unaware patients (P < 0.01, 0.03, and 0.01, respectively). Moreover, although the magnitudes of their plasma catecholamine responses and autonomic symptoms were reduced (both, P < 0.01), the plasma catecholamine levels at which autonomic symptoms began was not altered. Finally, as seen from glucose infusion rates necessary to maintain identical plasma glucose levels, patients with hypoglycemia unawareness had increased sensitivity to insulin (P < 0.001).
Our results confirm an association between hypoglycemia unawareness and duration of diabetes, glycemic control, and occurrence of severe hypoglycemia, and in addition provide evidence that both autonomic and neuroglycopenic symptoms are affected and that insulin sensitivity is increased, but beta-adrenergic sensitivity is not diminished.
Article: The effects of acute hypoglycaemia on memory acquisition and recall and prospective memory in type 1 diabetes.[show abstract] [hide abstract]
ABSTRACT: Global memory performance is impaired during acute hypoglycaemia. This study assessed whether moderate hypoglycaemia disrupts learning and recall in isolation, and utilised a novel test of prospective memory which may better reflect the role of memory in daily life than conventional tests. Thirty-six subjects with type 1 diabetes participated, 20 with normal hypoglycaemia awareness (NHA) and 16 with impaired hypoglycaemia awareness (IHA). Each underwent a hypoglycaemic clamp with target blood glucose 2.5 mmol/l. Prior to hypoglycaemia, subjects attempted to memorise instructions for a prospective memory task, and recall was assessed during hypoglycaemia. Subjects then completed the learning and immediate recall stages of three conventional memory tasks (word recall, story recall, visual recall) during hypoglycaemia. Euglycaemia was restored and delayed memory for the conventional tasks was tested. The same procedures were completed in euglycaemic control studies (blood glucose 4.5 mmol/l). Hypoglycaemia impaired performance significantly on the prospective memory task (p = 0.004). Hypoglycaemia also significantly impaired both immediate and delayed recall for the word and story recall tasks (p < 0.01 in each case). There was no significant deterioration of performance on the visual memory task. The effect of hypoglycaemia did not differ significantly between subjects with NHA and IHA. Impaired performance on the prospective memory task during hypoglycaemia demonstrates that recall is disrupted by hypoglycaemia. Impaired performance on the conventional memory tasks demonstrates that learning is also disrupted by hypoglycaemia. Results of the prospective memory task support the relevance of these findings to the everyday lives of people with diabetes.Diabetologia 02/2007; 50(1):178-85. · 6.81 Impact Factor
Diabetes care 09/2009; 32(8):1357-63. · 8.09 Impact Factor
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ABSTRACT: individuals with type 1 diabetes mellitus (T1DM) are encouraged to consume CHO to prevent hypoglycemia during or after exercise. However, the research comparing specific types of CHO is limited. This study compared the alterations in metabolism and fuel oxidation in response to running after preexercise ingestion of isomaltulose or dextrose in T1DM. after preliminary testing, on two occasions, eight T1DM individuals consumed 75 g of either dextrose (DEX; GI = 96) or isomaltulose (ISO; GI = 32), 2 h before performing 45 min of treadmill running at 80% ± 1% VO(2peak). Blood glucose (BG) was measured for 2 h before and 3 h after exercise. Cardiorespiratory parameters were collected at rest and during exercise. Data (mean ± SEM) were analyzed using repeated-measures ANOVA. there was a smaller increase in BG in the preexercise period under ISO with peak BG occurring at 120 min after ingestion compared with 90 min under DEX (Δ+4.5 ± 0.4 vs Δ+9.1 ± 0.6 mmol·L, P < 0.01). During the final 10 min of exercise, there were lower CHO (ISO 2.85 ± 0.07 vs DEX 3.18 ± 0.08 g·min, P < 0.05) and greater lipid oxidation rates (ISO 0.33 ± 0.03 vs DEX 0.20 ± 0.03 g·min, P < 0.05) under ISO. After exercise, ISO BG was lower than DEX for the entire 180-min period, with BG area under the curve and mean BG concentrations being 21% ± 3% and 3.0 ± 0.4 mmol·L lower, respectively (P < 0.05). consumption of ISO improves BG responses during and after exercise through reduced CHO and improved lipid oxidation during the later stages of exercise.Medicine and science in sports and exercise 02/2011; 43(2):204-10. · 3.71 Impact Factor