Many people with diabetes get much worse when they start using insulin. I know it's important to control the blood sugar, but it also affects the potassium shift in the cells and that's what makes us worse. If you're on a drug to stimulate the pancreas to produce more insulin it can have a similar effect.
And usually when doctors treat diabetes, they also treat the high cholesterol/triglycerides that go along with it, and all the statin drugs are contraindcted with myotonia congenita. Two people in my family who had the mutation for MC but had no symptoms suddenly had problems when they were put on cholestrerol medication.
If you have high triglycerides it is much safer for us to use fish oil supplements, L-Carnitine and Alpha Lipoic Acid to lower the levels. I'll paste in a list of contraindicated medications which includes the trade names for the statin drugs.