Abstract
BACKGROUND: This randomized, controlled trial evaluated a monetary-based reinforcement intervention for increasing self-monitoring of blood glucose (SMBG) among youth with poorly controlled type 1 diabetes. METHODS: After a 2-week baseline, 60 participants were randomized to enhanced usual care (EUC) or Reinforcers. The Reinforcers group earned monetary rewards for SMBG and associated behaviors such as uploading glucose meters. Reinforcers were withdrawn at 24 weeks. A follow-up evaluation occurred at 36 weeks. RESULTS: Participants in the reinforcers group increased the proportion of days they completed ≥4 SMBG from 14.6% at baseline to 64.4%, 47.5%, and 37.8% at 6, 12, and 24 weeks, respectively. In contrast, EUC participants declined from 22.7% at baseline to 17.5%, 10.5%, and 11.1% (Ps < .01 vs EUC at all time points). Group differences were attenuated but remained significant after withdrawal of reinforcers. Effect sizes for SMBG were very large during reinforcement and large after withdrawal of reinforcers. In the reinforcers group, mean A1c dropped from 9.5% ± 1.2% at baseline to 9.0% ± 1.3% at week 6 and 9.0% ± 1.4% at week 12. For EUC, A1c was 9.2% ± 0.2% at baseline and ranged from 9.2% ± 1.5% to 9.6% ± 1.6% throughout the study (P < .05 vs EUC). Group differences in A1c were no longer significant at weeks 24 and 36. Effect sizes for A1c were small during reinforcement and also after withdrawal of reinforcement. CONCLUSIONS: Monetary-based reinforcement of adolescents with type 1 diabetes caused durable increases in SMBG. Modification of the reinforcement structure may be needed to sustain improved metabolic control in this challenging age group.