What Does A Recent Lab Report Reading Of 123 Mg/dL

What does a recent lab report reading of 123 mg/dL and marked high mean? Last time was 104, also marked high. The eGFR 43 marked low and time before 52, also marked low. I am 77. Dr said it's OK for my age but wants to watch more closely. Have had the high and low readings for years but he never mentioned them before. Do not have diabetes or high BP. Thank you.