P.18.8 Day profile of plasma glucose in diabetic-complicated myotonic dystrophy type 1

Abstract

Diabetes mellitus is one of well-known complications in myotonic dystrophy type 1 (DM1). Prolonged hyperglycemia and hyperinsulinemia after glucose loading are characteristic features of glucose intolerance in DM1. Different mechanism of impaired glucose regulation in DM1 from that of type 2 Diabetes is assumed. The aim of this study was to investigate day profile of plasma glucose (PG) in DM1 with diabetes mellitus. Eighteen DM1 patients with diabetes mellitus (9 females and 9 males; the mean age, 52.8 years; the mean HbA1c, 7.1%) and eleven DM1 patients diagnosed as the impaired glucose tolerance (IGT) by 75 g oral glucose tolerance test (2 females and 9 males; the mean age, 49.1 years; the mean HbA1c, 5.1%) were participated. PG and immunoreactive insulin (IRI) were examined at 30 min before and 2 h after the daily meals. Day profile patterns of the PG and IRI curves were evaluated. Area under the curve (AUC) of PG during each meal was analyzed. Day profiles of PG in diabetic patients with DM1 demonstrated a pattern in which PG level tended to rise in the afternoon through evening, whereas those in IGT patients with DM1 showed almost same peaks of PG after each meal. Hyperglycemia in the afternoon was observed even in patients with normal fasting PG. Day profile patterns of IRI were widely varied individually in both of diabetes and IGT patients with DM1. AUC of PG for dinner was significantly larger than that for breakfast in diabetic patients with DM1. AUC of PG for lunch showed a tendency of getting larger compared to that for breakfast, and also that for dinner against that for lunch, without statistical significance. There was no significant difference among AUCs of PG for the three meals in IGT patients with DM1. PG level in diabetic-complicated DM1 tends to rise in the afternoon through the evening. Hyperglycemia from noon to evening should be noted in treatment for glucose impairment in patients with DM1.