Diabetes Mellitus is caused by the inability of the pancreas to produce insulin, diabetes continues to increase every year due to heredity, obesity, diet. Robusta coffee contains chlorogenic acid which is effective in controlling hyperglycemia conditions. The purpose of the study was to determine the effect of high-fat diet on HbA1c rats and ethanol extract of robusta coffee beans in type 2 diabetes mellitus rats. The research method was pre and post test by maceration extraction of robusta coffee beans, as many as 25 rats of glazed wistar, divided into 5 groups. . Induction of high-fat diet for 13 weeks, HbA1C examination using the ELISA method. Group 1 was given a high-fat diet, group 2 was given metformin, groups 3, 4 and 5 were given ethanol extract of robusta coffee beans, respectively 200, 300 and 400 mg/kg BW. The administration was given orally for 5 weeks, the volume of administration was 5 mL/200 g BW, the blood glucose levels of rats were measured every week. The results of the measurement of HbA1C levels during high-fat diet showed that 25 rats with NGSP values above 7 mmol/mol. The percentage decrease in blood glucose levels in rats was 7.97% at a dose of 200 mg/kgBW, 22.11% at a dose of 300 mg/kgBW and 31.70% at a dose of 400 mg/kgBW. The results of the study concluded that high-fat diet feed had an effect on increasing HbA1C levels in rats for Robusta coffee bean ethanol extract had an antihyperglycemic effect in type 2 diabetes mellitus rats. popular with the public