A cross-sectional study for glucose intolerance of myotonic dystrophy

We made a cross-sectional study to analyze glucose intolerance of myotonic dystrophy type 1 (DM1) with several examination including oral glucose tolerance test (OGTT), insulin tolerance test (ITT) and adiponectin. Ninety-five DM1 patients participated in this study. Health examination data from general people were used as controls. In DM1, homeostasis model assessment-insulin resistance (HOMA-IR) was higher than control even in the lowest fasting blood sugar (FBS) stage (<80 mg/dl) and insulin sensitivity assessed by ITT was low regardless of their FBS. Insulinogenic index of DM1 was positively correlated to HOMA-IR. Insulinogenic index and sum of IRI in OGTT were markedly elevated in the lowest FBS stage and declined along with elevation of FBS. Consequently, as many as 13.3% of DM1 patients with 90-110 mg/dl of FBS exhibited DM pattern, while only 1.9% in control. Adiponectin was higher in DM1 than control. Although age correlated with adiponectin in both control and DM1, its impact was stronger in DM1. DM1 predisposes insulin resistance and compensatory hyperinsulinemia exist even in patients with low FBS. We should pay attention to glucose intolerance of DM1 patients earlier than that of the general population. It seemed that 90 mg/dl of FBS is an important index as an indication of careful managements.