Continuous glucose monitoring adds information beyond HbA1c in well-controlled diabetes patients with early cardiovascular autonomic neuropathy.

AIMS: Hyperglycemia as evaluated by HbA1c is a risk factor for the development of cardiovascular autonomic neuropathy (CAN). The aim of the present study was to investigate whether continuous glucose monitoring (CGM) may add information beyond HbA1c in patients with type 2 diabetes and CAN. METHODS: 81 patients with type 2 diabetes (43 men, mean age 58±11year, HbA1c 6.6±0.5%). Patients were tested for CAN using cardiovascular reflex tests (response to standing, deep breathing and Valsalva maneuver) and underwent CGM for three days. CAN was defined as early (one test abnormal), or manifest (two or three tests abnormal). RESULTS: Twenty patients had early CAN and two patients had manifest CAN. Blood pressure, HbA1c, cholesterol levels and smoking habits were comparable in patients with vs. without CAN. Post-breakfast glycemic peak was significantly higher in patients with CAN (peak 207 vs 176mg/dL, P=0.009). Furthermore, the nocturnal glucose drop and dawn glucose was significantly higher in patients with CAN compared with patients without CAN (mean 134 vs. 118mg/dL, P=0.017 and mean 143 vs. 130mg/dL, P=0.045, respectively). Removing the two patients with manifest CAN from the statistical analysis didn't change the results. CONCLUSIONS: These findings emphasize the importance of monitoring glucose patterns over 24-h and not only rely on HbA1c as therapeutic target in patients with type 2 diabetes and CAN.

Glycemic variability is associated with reduced cardiac autonomic modulation in women with type 2 diabetes.

OBJECTIVE: To investigate the sex differences in cardiac autonomic modulation in patients with newly diagnosed type 2 diabetes and to determine whether cardiac autonomic modulation is associated with glycemic variability. RESEARCH DESIGN AND METHODS: We investigated a cohort consisting of 48 men and 39 women with non-insulin-treated type 2 diabetes and a known duration of diabetes <5 years. All patients were equipped with a continuous glucose monitoring sensor for 3 days, and the mean amplitude of glycemic excursions (MAGE) was calculated to obtain individual glycemic variability. Cardiac autonomic modulation was quantified by analysis of heart rate variability (HRV) in time and frequency domains and during cardiovascular reflex tests (response to standing [RS], deep breathing [expiration-inspiration], and Valsalva maneuver). RESULTS: Sex differences in age- and heart rate-adjusted HRV measures were observed in both active and passive tests. Low frequency (LF; P = 0.036), LF/high frequency (HF; P < 0.001), and RS (P = 0.006) were higher in men, whereas expiration-inspiration (P < 0.001), but not HF, was higher in women. In women, reduced cardiac autonomic modulation as assessed by the standard deviation of normal-to-normal intervals (P = 0.001), the root mean square of successive differences (P = 0.018), LF (P < 0.001), HF (P = 0.005), total power (P = 0.008), RS ratio (P = 0.027), and expiration-to-inspiration ratio (P = 0.006) was significantly associated with increased glycemic variability as assessed by MAGE. This was not the case in men. The association in women persisted in a multivariate regression analysis controlling for weight, mean heart rate, blood pressure (systolic), and triglycerides. CONCLUSIONS: In patients with newly diagnosed and well-controlled type 2 diabetes, increased glycemic variability was associated with reduced cardiac autonomic modulation in women but not in men.

Assessment of postprandial glucose excursions throughout the day in newly diagnosed type 2 diabetes.

BACKGROUND: A growing body of evidence suggests that postprandial glucose (PPG) is independently linked to multiple complications and that testing of PPG should be added to hemoglobin A1c (HbA1c) and fasting glucose measurements in the evaluation of glycemic control of type 2 diabetes patients. An ongoing debate is questioning how to assess PPG. This observational study looks further into this question in a cohort of newly diagnosed type 2 diabetes patients. SUBJECTS AND METHODS: PPG characteristics and intra-/intersubject variations post-breakfast, -lunch, and -dinner, obtained from continuous glucose monitoring (CGM), were retrospectively analyzed in 86 newly diagnosed non-insulin-treated type 2 diabetes patients. RESULTS: In total, 462 recorded meals were analyzed. The area under the curve 1-4 h postmeal was significantly larger after breakfast compared with both lunch and dinner (P<0.001). Time to peak was approximately 90 min and did not differ significantly between meals. However, the distribution of the blood glucose peaks was only normally distributed among breakfasts, and time to peak had a day-to-day correlation coefficient of 0.60, compared with a nonsignificant result for lunch and dinner. Breakfast PPG peaks were highly correlated to HbA1c (P<0.05, r=0.64) and had a day-to-day correlation coefficient of 0.86 compared with 0.44 for lunch and 0.74 for dinner. CONCLUSIONS: Self-monitoring of blood PPG should be evaluated with care. From our data, monitoring of PPG patterns in newly diagnosed type 2 diabetes patients should preferably be obtained following breakfast for a more consistent assessment, reducing day-to-day variations.