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Blood Glucose Control

Central Analysis of HbA1C

In all the studies, HbA1C was centrally analysed at the Steno Diabetes Center using the same calibrator lots as the Diabetes Control and Complications Trial (DCCT) laboratory. By direct sample exchange, the Steno Diabetes Center HbA1C results were found to be 0.3% higher than the DCCT levels.

Blood Glucose Control

The first cross-sectional study was designed to evaluate the current level of metabolic control in children and adolescents with insulin-dependent diabetes mellitus (IDDM). This was presented in the paper Comparison of metabolic control in a cross-sectional study of 2,873 children and adolescents with IDDM from 18 countries.1

Figure 1
Centres sorted according to their mean HbA1C levels adjusted for age, sex, and diabetes duration. The grand mean for HbA1C was 8.6% (indicated by horizontal line). Mean ± 1 SE value is shown.

Reproduced from Danne et al. Diabetes Care 2001; 24(8): 1342-7

In this cross-sectional survey of 21 paediatric departments, representing 18 countries in Europe, Japan, and North America, the grand mean HbA1C value was 8.6 ± 1.7% (mean ± SD) but varied significantly (p < 0.0001) between centres, irrespective of the insulin regimen used (Figure 1).

The mean HbA1C of 8.6% corresponds to 8.3% in the DCCT (adjusted by direct sample exchange) and is thus comparable with that of the adolescents in the DCCT, in which the intensive treatment group had a mean HbA1C of 8.1% (versus 9.8% in the conventional treatment group).

Seven centres had a mean HbA1C significantly above the grand mean for HbA1C (p < 0.05) and six centres significantly below (p < 0.05), while eight centres did not differ significantly from the average HbA1C value. Interestingly, blood glucose control was similar in patients treated with three or more daily insulin injections compared with patients on twice-daily insulin. The differences between centres were not readily explicable in terms of geography or the organisational structure of the clinics. In virtually all centres, diabetes management used a multidisciplinary healthcare team approach, with paediatric endocrinologists, diabetes nurses, dieticians, social workers, and other healthcare professionals involved in the care of children with diabetes.

Figure 2
Incidence of hypoglycemia (unconsciousness/seizures) during a three-month observation period in 2,807 children and adolescents with type 1 diabetes (n = number of patients in each age group).

Reproduced from Mortensen et al. Diabetes Care 1997; 20(5): 714-20

Hypoglycaemia resulting in seizures/unconsciousness was related to younger age (0–8 years) (Figure 2) and lower HbA1C level. The overall incidence was 22 per 100 patient-years, which is comparable to the numbers reported in the DCCT for adolescents on conventional treatment.6,7 A major obstacle to achieving and maintaining near-normalisation of blood glucose control is the fear of inducing hypoglycaemia in children and adolescents, with their greater irregularities in diet and exercise than adults. The higher incidence of severe hypoglycaemic episodes observed in younger children reflects the fact that young children are less likely to be aware that a hypoglycaemic episode is approaching and to warn people around them, and implies that tight control in this age group should be undertaken with extreme caution as hypoglycaemia may impair normal brain development.8

Figure 3
Age-specific mean values for HbA1C in 1,443 boys (dashed line curve) and 1,430 girls (full line curve) with Type 1 diabetes. The error bars represent 1SEM value (*p <0.05, ** p <0.01 in comparison of boys and girls in each age group).

Reproduced from Mortensen et al. Diabetes Care 1997; 20(5): 714-20

The results of this study also confirmed that blood glucose control, as assessed by HbA1C, was poorest during puberty (Figure 3). The elevated level of HbA1C (9.0– 9.5%) was found despite the fact that 38% of these young people were on three or more insulin injections daily. The unsatisfactory control observed during puberty may be due to decreasing levels of adherence to different aspects of the treatment regimen, as well as to the decreasing insulin sensitivity of peripheral tissues during adolescence.

Conclusion:
The overall glycaemic control in this cross-sectional study was comparable to that of the adolescent group in the DCCT, though the rate of hypoglycaemic events was slightly lower. A significant difference in blood glucose control across centres was shown.

Reference

1. Mortensen HB, Hougaard P. Comparison of metabolic control in a cross-sectional study of 2,873 children and adolescents with IDDM from 18 countries. The Hvidøre Study Group on Childhood Diabetes. Diabetes Care 1997; 20(5): 714-20.

6. Diabetes Control and Complications Trial Research Group. Effect of intensive diabetes treatment on the development and progression of long-term complications in adolescents with insulin-dependent diabetes mellitus: Diabetes Control and Complications Trial. J Pediatr 1994; 125(2): 177-88.

7. Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993; 329(14): 977-86.

8. Rovet JF, Ehrlich RM, Czuchta D et al. Psychoeducational characteristics of children and adolescents with insulin-dependent diabetes mellitus. J Learn Disabil 1993; 26(1): 7-22.