This is interesting since I am in the same situation. My sister has triglycerides that scare doctors (low for her is around 500 and high is in the 2500-5000 range). Mine are typically well under 50. However, she has not been shown to have any blood sugar problems and I have been dealing with one sort or another almost my entire life. I did wonder the same thing about insulin sensitivity since my fasting c-peptide is also low, yet my A1C is just pre-diabetic and my fasting BG is normal when on a low-carb diet. I've never had a stimulated c-peptide test, however. I have trouble believing I have insulin resistance since I have a low fasting c-peptide and low triglycerides and cholesterol and blood pressure, but my history (reactive hypoglycemia, gestational diabetes, and pre-diabetes) follows the history of excessive insulin production. Who knows?