First test effect in intravenous glucose tolerance testing.

AIMS: Intravenous glucose tolerance testing (IVGTT) is a common test of ß-cell function in which a glucose load is administered and insulin and/or C-peptide responses are monitored. Since the first IVGTT may be more stressful and stress may alter ß-cell secretion or hepatic insulin extraction, we asked whether there was a first test effect. METHODS: Insulin and C-peptide responses were compared from two sequential IVGTTs performed within 6 months during staging for the Diabetes Prevention Trial-Type 1 (DPT-1) in 368 people at high risk for type 1 diabetes. Insulin data (1+3 min) were used because the first phase insulin response (and peak insulin concentration) occurs within this time frame. Areas under the curve (AUC) calculations represent early insulin or C-peptide responses from 0 through 10 min post-glucose challenge. RESULTS: More than half of all subjects were found to have first test values lower than the second. This was true for all measures of both insulin and C-peptide but the frequency was significantly different only for insulin measures corrected for basal and for insulin AUC (p < 0.05). However, for subjects (n = 99) whose 1+3 min insulin response was <10th percentile on the first test, there was a significant increase on the second test (p < 0.05). The C-peptide: insulin ratio did not change significantly between tests, indicating that differences are due to changes in ß-cell secretion rather than hepatic insulin uptake. CONCLUSIONS: A statistically significant first test effect occurs during the IVGTT attributable to variations in insulin secretion rather than hepatic uptake.

Changes in headache frequency in premenopausal obese women with migraine after bariatric surgery: a case series.

BACKGROUND: The association between migraine and obesity gives the clinician with an exciting possibility to alleviate migraine suffering through weight-reduction gastric-restrictive operations. We hypothesized that bariatric weight-reduction intervention (gastric banding) will be associated with reduction of migraine burden in this population. METHODS: A total of 105 women between 18 and 50 years of age, admitted for bariatric surgery between April 2006 and February 2007, were screened for migraine. Twenty-nine with diagnosis of migraine were enrolled into the prospective phase. We followed the migraine pattern of these patients for 6 months post bariatric surgery. RESULTS: Baseline median migraine frequency was six headache days a month. Post bariatric surgery, the migraine-suffering women reported of a lower frequency of migraine attacks (p < 0.001), shorter duration of the attacks (p = 0.02), lower medication use during the attack (p = 0.005), less non-migraine pain (44.8 vs. 33%, p = 0.05), and post-bariatric surgery reduction in headache-related disability assessed by the MIDAS and HIT-6 scores. There was a reduction in migraine frequency among both episodic (from four to one episodes a month) and chronic (from 16.8 to 8.5 episodes per month) migraine patient cohorts separately and combined. CONCLUSIONS: Among migraine-suffering premenopausal obese women, we found a reduced frequency of migraine attacks and improvement of headache-related disability post bariatric surgery. Our findings should be interpreted cautiously. The absence of a control group and the non-blinded nature of our small study make it difficult to draw firm conclusions about the causal nature of the headache changes observed in this population. Further study is needed to evaluate the possible specific effects of surgical weight loss on migraine in obese women.