Irregular meal pattern has become more prevalent during the last decade (Samuelson, 2000). No studies have evaluated the association between irregular meal pattern and carbohydrate metabolism. The purpose of this study was to investigate the impact of irregular meal frequency on blood glucose and serum insulin response.

Nine healthy, lean women aged 18-42 years gave informed vountary consent to participate in a randomised cross-over trial consisting of four phases over a total of 71 days. Subjects were studied after an overnight fast at the start and end of phases 1, 2 and 4. In phase 1, subjects were asked to eat their normal diet for 28 days. In phase 2 (14 days), they were asked to consume similar things as normal but either on six occasions per day (regular meal pattern) or follow a predetermined irregular meal pattern (3-9 meals per day), which had the same total number of meals over the 14 days. In phase 3 (14 days), subjects continued their normal diet as a wash-out period. In phase 4 (14 days), subjects followed the alternative meal pattern to that followed in phase 2.

At each laboratory visit, two baseline blood samples were taken for fasting blood glucose and serum insulin before a high carbohydrate test meal (42 kJ kg^-1) was consumed. Blood samples were then taken every 15 min for 3 h and analysed for blood glucose and serum insulin. Total volume of blood sampled at each visit was 70 ml.

There was no difference in fasting blood glucose and serum insulin, or, area under the curve (AUC) for post-prandial blood glucose over the experiment. A significant increase in serum insulin concentration occurred after the test meal in all visits. No significant changes were observed in the peak insulin value or AUC of the insulin response between the pre-diet visits. In contrast, the peak insulin levels at the post-diet visits were significantly different after normal, regular and irregular diet periods (mean ± S.D. (mIU l^-1) was 63.4 ± 22.9, 55.4 ± 17.9 and 71.4 ± 25.0, respectively, P = 0.017, ANOVA). AUC of insulin response for the post-diet visits were also statistically different (P = 0.013, ANOVA).

Irregular meal frequency had no effect on glucose tolerance. However, there was an increased post-prandial insulin response, suggesting a degree of insulin resistance after the irregular meal pattern.