Objective To study the characteristics of daily blood glucose profiles in diabetic patients receiving methylprednisolone and to provide an optimal adjustment of insulin for glucocorticoid-induced hyperglycemia.Methods Patients with chronic obstructive pulmonary disease(COPD) and diabetes not treated with methylprednisolone (group DM1),COPD with diabetes (group DM2) or without diabetes (group NDM) treated with methylprednisolone were studied by means of continuous glucose monitoring system(CGMS) for3 days.Levels of mean blood glucose(MBG),the area under the curve of postprandial glucose above 11.1 mmol/L(AUC),percentage of time spent in hyperglycemia above 10 mmol/L (PT),postprandial glucose spike (PGS),postprandial glycemic excursion (PPGE),and mean amplitude of glycemic excursions(MAGE) were calculated in each individual.Changes of insulin doses after using methylprednisolone in group DM2 were observed.Results The 24 h MBG in group DM2 was 42％ higher than that in group DM1 and 38％ higher than that in group NDM(P＜0.05).AUC,PT,and MAGE were significantly higher in group DM2 than in group DM1 and NDM (P＜0.01).PGS and PPGE after breakfast in group DM2 were significantly higher than those in group NDM (P＜0.01),but there was no significant difference between group DM2 and DM1 (P＞0.05).PGS and PPGE after lunch and dinner in group DM2 were both significantly higher than those of in group DM1 and group NDM (P＜0.01),and both lunch and dinner yielded higher PGS and PPGE than those after breakfast in group NDM and group DM2 (P＜0.05).The peak of plasma glucose in group NDM occurred at 70-80 min after lunch,ie.about (5.71 ± 0.56) h after methylprednisolone administration.However,the peak occurred at about 1.5 h after dinner in group DM2.Insulin doses were significantly increased by 74％ in patients with COPD and diabetes after treatment with methylprednisolone (P＜0.01).The insulin doses before lunch and dinner were 53％-67％ higher than those before breakfast(P＜0.01).Conclusions The daily blood glucose peak in COPD patients without diabetes mostly occurred after lunch during treatment with methylprednisolone.In eontrast,in COPD patients with diabetes,the peak glucose level occurred 1.5 h after dinner.I1 is suggested that insulin doses should be increased by 50％ when the glucocortieoid therapy is started and may need to be increased by 74％ or more to control blood glucose levels.The increased insulin doses should be distributed before lunch and dinner.