Abstract: Fasting serum insulin,C peptide and glucose levels were mearsured in 40 patients suffering from chronic congestive heart failure （CHF） and 11 healthy persons.The CHF was the result of coronary atherosclerosis,rheumatic valve disease,hypertension and cardciomyopathy.Serum insulin levels were decreased in all chronic CHF patients,and the levels of insulin were directly proportional to the severity of chronic heart failure.The severer the CHF,the lower the serum insulin levels.The seurm insulin levels in the controls were 8.684 7±0.606 1 mU/L and this confrms to other domestic and iverseas reports.In CHF,degree Ⅰ、Ⅱ、Ⅲ were 6.890 5±0.601 4 mU/L,3.895 6±0.319 3 mU/L,0.899 6±0.187 3 mU/L respectively.However,the seurm C peptide levels which represent initial insulin secreting function of islets of Langerhans and gluccse levels had no significant difference between the control group and the patient group.The seurm insulin levels in those patienis who were treated with angiotensin converting ensyme inhibitors and calcium blockers which were reported to affect insulin levels revealed no significant difference compared with those not treated.The result of this study shows that the reduction of serum insulin levels in CHF is not caused by defect of secreting function of islets of Langerhans but by over insulin consumption in the jeopardized myocardium.It is mainly related to myocardial protections The clinical significance of this study might be:（1）Decrease of serum insulin levels is a common phenomenon in chronic CHF,and it is due to insulin iver consumption in the jeopardized myocardium,this offers us theoretical support to treat CHF with glucose insulin potassium solution;（2）Measuring the serum insulin levels in CHF could help to evaluate the severity of CHF.