Glucose fluctuations in subjects with normal glucose tolerance, impaired glucose regulation and newly diagnosed type 2 diabetes mellitus

Objective Glycemic variability is poorly studied in the nondiabetic individuals and newly diagnosed patients with type 2 diabetes. The aim of the study is to investigate the characteristics of glucose fluctuations in subjects with normal glucose tolerance (NGT), impaired glucose regulation (IGR) and newly diagnosed, drug‐naïve type 2 diabetes mellitus (DM‐2). Design and patients This is a cross‐sectional study of three groups including 53 subjects with IGR, 56 DM‐2 patients and 53 NGT individuals. Monitoring by a continuous glucose monitoring system (CGMS^® System Gold^?) was performed for three consecutive days. Measurements Mean blood glucose (MBG), standard deviation of MBG (SDBG), largest amplitude of glycemic excursions (LAGE) and mean amplitude of glycemic excursions (MAGE) were calculated to estimate intraday blood glucose variability. Interday variability of glucose was evaluated by absolute means of daily differences (MODD). Postprandial glucose excursion (PPGE) was calculated to assess the influence of meals on glucose fluctuation. Results Twenty‐two percentage of NGT and 33·9% of IGR individuals experienced blood glucose ≥11·1 mmol/l; 49·1% of NGT, 50·9% of IGR and 30·8% of DM‐2 participants had hypoglycemic episodes (CGM values <3·9 mmol/l). The IGR and DM‐2 groups had greater SDBG (P = 0·010 and P < 0·001), LAGE (P = 0·014 and P < 0·001) and MAGE (P = 0·044 and P < 0·001) compared with the NGT group. Significantly greater MODD and PPGEs were found in the DM‐2 groups than in the IGR and NGT groups (P < 0·001). The DM‐2 patients had higher 72‐MBG and glucose levels overnight than the NGT and IGR subjects (P < 0·001). In the patients with diabetes, MAGE was positively associated with MODD (r = 0·558, P < 0·001) and PPGEs (r = 0·738–0·843, P < 0·001). Conclusions Glucose variability is present to an increasing degree from NGT to IGR and IGR to DM‐2. Compared with the NGT individuals, the IGR and DM‐2 subjects show more predominant intraday glucose fluctuations. The DM‐2 patients demonstrate increased PPGEs, higher glucose levels overnight and greater interday fluctuations.