Like "Well the c-peptide is just one of the necessary test to check for Type 1.5 the other is called a (GAD) antibodies test. A Glutamic Acid Decarboxylase Autoantibodies test (GAD antibodies test) is used to help discover whether someone has either type 1 diabetes or Latent Autoimmune Diabetes of Adulthood (LADA). A GAD test is a blood test which measures whether the body is producing a type of antibody which destroys its own GAD cells. In type 1 diabetes, a number of autoantibodies are thought to circulate including those which target glutamic acid decarboxylase. The presence of these autoantibodies suggests type 1 diabetes. Both the Type 1 and Type 1.5 have these autoantibodies in common the type 2 however do not have these present. I wish you good luck , finding the right diagnosis changes the treatment. Many of the drugs used for type 2 have little to no effect treating a type 1 or 1.5 LADA. Insulin is the only viable treatment other than diet and exercise to lower glucose levels since these types produce to little or none of their own body insulin. The body has destroyed its ability to produce its own insulin. I think I have had LADA a long time before being correctly diagnosed or diagnosed with diabetes in any form. The reason I think this is because of the complications my body has recieved which were being treated individually for symptoms instead of looking at the cause. Much of this damage could have been prevented if it were treated early at the cause. Hopefully I will be able to reverse some of that damage but eventually it will come back. Here is a link explaining LADA: https://timesulin.com/what-is-lada-diabetes/"