Longitudinal relationship of asymptomatic hypoglycemia to cognitive function in IDDM
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M P Golden1, G M Ingersoll, C J Brack
1Department of Pediatrics, Indiana University, Indianapolis.
Insights
Early-onset insulin-dependent diabetes mellitus (IDDM) is linked to learning deficits. Frequent asymptomatic hypoglycemia, not severe episodes, correlated with lower abstract/visual reasoning and copying scores in children with IDDM.
Area of Science:
- Pediatrics
- Endocrinology
- Neuroscience
Background:
- Early-onset insulin-dependent diabetes mellitus (IDDM) is associated with learning deficits.
- Metabolic control is a potential factor influencing cognitive outcomes in children with IDDM.
Purpose of the Study:
- To investigate the relationship between learning deficits and metabolic control in children with early-onset IDDM.
- To determine if severe hypoglycemia or asymptomatic hypoglycemia impacts cognitive function.
Main Methods:
- 23 children with IDDM diagnosed before age 5 were followed for 6-78 months.
- Collected data included glycosylated hemoglobin (HbA1), severe hypoglycemia, and asymptomatic hypoglycemia (SMBG < 2.8 mM).
- Cognitive function was assessed using the Stanford-Binet Intelligence Scale.
Main Results:
- No correlation was found between severe hypoglycemia and cognitive subscales.
- Asymptomatic hypoglycemia frequency correlated with lower abstract/visual reasoning (r = -.39, P = .037) and copying subscale scores (r = -.42, P = .022).
- Children with frequent asymptomatic hypoglycemia had poorer performance on these cognitive measures.
Conclusions:
- Asymptomatic hypoglycemia, rather than severe hypoglycemia, is associated with specific learning deficits in children with early-onset IDDM.
- Maintaining stable blood glucose levels and avoiding frequent asymptomatic hypoglycemic episodes may be crucial for cognitive development in this population.
Abstract:
Early-onset insulin-dependent diabetes mellitus (IDDM) is linked to subsequent learning deficits. To investigate the relationship of learning deficits to metabolic control, 23 children with IDDM (age at testing 71 +/- 21 mo, age at diagnosis 35 +/- 15 mo) diagnosed before 5 yr of age were followed for periods of 6-78 mo. Mean glycosylated hemoglobin (HbA1), episodes of severe hypoglycemia, and frequency of self-monitoring blood glucose (SMBG) measurements less than 2.8 mM (50 mg/dl, asymptomatic hypoglycemia) were recorded every 3 mo. Six subjects entered the study 12.3 +/- 6.7 mo after diagnosis, and only severe hypoglycemia was present before entry. For the remaining 17 subjects, HbA1 and severe and asymptomatic hypoglycemia were present from the time of diagnosis of diabetes. Mean HbA1 level was 10.1 +/- 1.0%, and mean severe hypoglycemic episodes per patient was 2.9, but the frequency was highly skewed; one patient had 37 episodes, and 14 had none. The mean percentage of SMBG readings less than 2.8 mM was 2.4 +/- 2.1. On the revised Stanford-Binet Intelligence Scale there was no correlation between any subscale and severe hypoglycemia. However, the relative frequency of asymptomatic hypoglycemia correlated with scores on the abstract/visual reasoning scale (r = -.39, P = .037). This relationship was primarily accounted for by the relationship of asymptomatic hypoglycemia to performance on the copying subscale (r = -.42, P = .022). Children with frequent asymptomatic hypoglycemic episodes had lower mean copying scores and abstract reasoning scores than those with infrequent episodes.(ABSTRACT TRUNCATED AT 250 WORDS)