Metabolic Control and Quality of Life
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.
Metabolic Control & Quality of Life
Both the DCCT and the recent ISPAD guidelines have recommended a treatment target for HbA1C of 7.5%. But how will the demands of good metabolic control influence the quality of life (QoL) of adolescents with diabetes? Stress caused by a demanding therapeutic intervention may adversely influence QoL and restrict the patient. The Hvidøre Study Group therefore decided to investigate the relationship between QoL, diabetes treatment regimens, and metabolic control in a large international cohort of adolescents with diabetes and their families. The results are presented in Good metabolic control is associated with better quality of life in 2,101 adolescents with type 1 diabetes.5
QoL in adolescents was assessed with a previously validated questionnaire.23 The questionnaire contained 52 items in four sections: impact of diabetes, worries about diabetes, satisfaction with life, and health perception. For each adolescent, one parent and one health professional completed a questionnaire, including five items about their perceptions of the burden on the family related to the adolescent's diabetes.
This is the first large, international, multi-language study evaluating the relationship between metabolic control and QoL in adolescents with diabetes. This study suggests that better metabolic control is associated with a better QoL for adolescents and with a lower perceived burden by parents and health professionals. Figure 10 shows the change in QoL score with age, according to sex and high and low HbA1C, selected as the 10th (6.8%) and the 90th percentiles (10.9%) in the population as perceived by adolescents, to illustrate a reasonable variation in QoL score due to metabolic control. All QoL scores were linearly transformed, so that the best possible score was 0 and worst possible score was 100. Few adolescents rated the disease impact as major (Figure 10a). Moreover, a lower impact score was significantly associated with better HbA1C. Impact of diabetes was similar in boys and girls, and neither age nor duration of diabetes had an impact on the scoring. More worries were evident with increasing age, especially in girls (Figure 10b). This may reflect the higher incidence of psychological disturbance widely reported in population studies of adolescent girls.24-27 The relationship between HbA1C and worry was just significant.
Figures 10a and b
The association of HbA1C (6.8% or 10.9%), sex, and age on (a) the impact of diabetes (lower score = less impact), and (b) worries about diabetes.
Reproduced from Hoey et al. Diabetes Care 2001; 24(11): 1923-8.
The scores for satisfaction followed the same pattern as worries, showing less satisfaction with increasing age, again more pronounced in girls (Figure 10c, overleaf). Teenage girls had poorer health perception than boys (Figure 10d, overleaf). Thus girls had worse metabolic control, higher BMI, and significantly poorer overall QoL at an earlier age than boys. These findings may be associated with earlier hormonal and pubertal changes in teenage girls,28,29 and with their relative lack of physical activity and abnormal eating behaviours.30,31
Figures 10c and d
The association of HbA1C (6.8% or 10.9%), sex, and age on (c) satisfaction with life, and (d) health perception score.
Reproduced from Hoey et al. Diabetes Care 2001; 24(11): 1923-8.
No correlation between adolescent QoL and burden perceived by parents and health professionals was observed, and this may reflect significant differences in perceptions of the impact of diabetes between adolescents and adults. Adolescents expressed less difficulty with diabetes than both adult groups. Also, patient and health professional ratings were only modestly correlated. These findings suggest the importance of assessing the perceptions of all three groups in the adolescent diabetes management trial. In contrast to the increasing worry and poorer satisfaction described by adolescents, parental assessment of family burden decreased with adolescent age, with parents of girls reporting the lowest burden. Because girls enter puberty earlier than boys, with an earlier transfer of responsibility for self-care management from parent to child, the parents' burden may be correspondingly decreased. By contrast, health professionals' scores for family burden showed no sex difference. For both parent and health professional ratings, higher HbA1C levels were associated with greater family burden. Thus knowledge of the consequences of poor control may result in increased parental and health professional concern.
Lower HbA1C is associated with better QoL. Although this study could not determine a causal relationship, efforts to achieve optimal metabolic control now seem justified on QoL as well as clinical grounds.5 The size and international nature of the study add credence to this assertion. As people with a higher QoL may be better equipped physically and psychologically to deal with the burdens of diabetes management, better QoL may facilitate better metabolic control through improved self-care as part of a positive cycle.
5. Hoey H, Aanstoot HJ, Chiarelli F et al. Good metabolic control is associated with better quality of life in 2,101 adolescents with type 1 diabetes. Diabetes Care 2001; 24(11): 1923-8.
23. Ingersoll GM, Marrero DG. A modified quality-of-life measure for youths: psychometric properties. Diabetes Educ 1991; 17(2): 114-18.
24. Petersen AC, Compas BE, Brooks-Gunn J et al. Depression in adolescence. Am Psychol 1993; 48(2): 155-68.
27. Kovacs M, Goldston D, Obrosky DS et al. Psychiatric disorders in youths with IDDM: rates and risk factors. Diabetes Care 1997; 20(1): 36-44.
28. Moran A, Jacobs DR Jr, Steinberger J et al. Insulin resistance during puberty: results from clamp studies in 357 children. Diabetes 1999; 48(10): 2039-44.
29. Holl RW, Siegler B, Scherbaum WA et al. The serum growth hormone-binding protein is reduced in young patients with insulin-dependent diabetes mellitus. J Clin Endocrinol Metab 1993; 76(1): 165-7.
30. Bryden KS, Neil A, Mayou RA et al. Eating habits, body weight, and insulin misuse. A longitudinal study of teenagers and young adults with type 1 diabetes. Diabetes Care 1999; 22(12): 1956-60.
31. Daneman D, Olmsted M, Rydall A et al. Eating disorders in young women with type 1 diabetes. Prevalence, problems and prevention. Horm Res 1998; 50(Suppl 1): 79-86.