Objectives: The goal of this study was to identify parental behaviors that relate to adherence and metabolic control in a population of young adolescents with insulin-dependent diabetes mellitus (IDDM), and to understand the interrelationships among the variables of parental involvement, adherence to blood glucose monitoring, and glycemic control. Study design: A cross-sectional design was used to investigate parental involvement in diabetes regimen tasks in 89 youth, aged 10 to l5 years, with IDDM. Levels of parental involvement in blood glucose monitoring (BGM) and insulin administration were evaluated through interviews. Assessment of adherence was made by physicians or nurses, independent of patient or parent reports of adherence. Glycemic control was assessed with glycosylated hemoglobin (HbA_lc ) (reference range, 4% to 6%). Results: There were significant differences in the mean HbA_lc values between the older (13 to 15 years of age) (HbA_lc = 8.9% ± 1.03%) and younger (10 to 12 years) patients (HbA_lc = 8.4% ± 1.06%) ( p <0.02). Parental involvement in BGM was significantly related to adherence to BGM (number of blood sugar concentrations checked daily) in both groups of adolescent patients. The younger patients monitored their blood glucose levels more frequently than did the older patients, 39% of the younger patients checked sugar concentrations four or more times daily compared with only 10% of the older group ( p <0.007). In a multivariate model controlling for age, gender, Tanner staging, and duration of diabetes, the frequency of BGM was a significant predictor of glycemic control ( R ² = 0.19, p <0.02). Increased frequency of BGM was associated with lower HbA_1c levels. When the frequency of BGM was zero or once a day, the mean HbA_1c level was 9.9% ± 0.44 (SE); when the frequency of BGM was two or three times a day, the mean HbA_1c level was 8.7% ± 0.17; and when the frequency of BGM was four or more times daily, the mean HbA_1c level was 8.3% ± 0.22. Conclusions: Parental involvement in BGM supports more frequent BGM in 10- to 15-year-old patients with IDDM. This increased adherence to BGM is associated with better metabolic control (i.e., lower HbA_1c levels). These findings suggest that encouraging parental involvement in BGM with 10- to 15-year-old patients with IDDM may help to prevent the well-documented deterioration in glycemic control and adherence to treatment that often occurs in later adolescence. (J Pediatr 1997;130:257-65)