Four chronic CFRD aged 15–29 years (previously treated with prandial bolus insulin for 1–3 years) vs. four intermittent CFRD aged 10–21 years (who had required insulin only during pulmonary exacerbation) vs. six intermittent CFRD controls aged 14–18 years (who did not receive insulin). The gene discussed is INS; the disease is cystic fibrosis-related diabetes.