Relationship of nocturnal hypoglycemia to daytime glycemia in IDDM.

In view of the continuing debate about the clinical relevance of nocturnal hypoglycemia as an explanation for high blood glucose (BG) levels before breakfast, we prospectively analyzed 281 overnight BG profiles (blood samples obtained at 2100, 0200-0300, and 0700) in 66 consecutive patients with insulin-dependent diabetes mellitus. Nocturnal hypoglycemia (0200-0300 BG concentration less than or equal to 50 mg/dl) occurred in 27 patients (41%) and in 36 profiles (13%). All the patients with nocturnal hypoglycemia received two or more injections of insulin each day. When hypoglycemia occurred at 0200-0300, the preceding BG concentration at 2100 was significantly lower than when nocturnal BG was greater than 100 mg/dl (108 +/- 11 vs. 145 +/- 12 mg/dl; P less than .05; mean +/- SE). A BG less than or equal to 120 mg/dl at 2100 preceded nocturnal hypoglycemia in 24 (67%) of 36 profiles. The mean BG at 0700 was significantly lower in the profiles associated with nocturnal hypoglycemia than in those with nocturnal BG levels greater than 150 mg/dl (156 +/- 10 vs. 201 +/- 11 mg/dl; P less than .05). BG values greater than 180 mg/dl at 0700 were infrequently (11 of 143 or 8% of profiles) preceded by nocturnal hypoglycemia, and no instances of major hyperglycemia (BG greater than 300 mg/dl) at 0700 were preceded by nocturnal hypoglycemia. Furthermore, BG at 0700, 1100, and 1500 on the day before the occurrence of nocturnal hypoglycemia were similar to those on the day after.(ABSTRACT TRUNCATED AT 250 WORDS)