Poor glycaemic control in pregnancy is a major factor leading to obstetric complications and future maternal-offspring diseases (e.g., macrosomia, diabetes). This phenomenon is evidenced in women with type 1 diabetes (T1DM), and is worrisome since it is aggravating the disease burden of this and next generations. Therefore, to find strategies aimed at breaking this intergenerational cycle has become a high-priority. Exercise is a promising tool to improve short-term glycaemic responses such as postprandial glucose peaks and glucose variability, and thus reduce adverse maternal-neonatal outcomes. However, it is unknown which timing of exercise is more effective to optimise postprandial glycaemic control in pregnant women with T1DM, and non-pregnant women (of reproductive age) with T1DM. The mechanisms underlying these benefits in T1DM and pregnancy are also to be established.~The MERIT1D project will unravel which timing of exercise (before or after a meal at lunchtime) is more effective to optimise postprandial glycaemic control in pregnant and non-pregnant women with T1DM, and the mechanisms underlying these metabolic responses. Ten pregnant women with T1DM and ten non-pregnant women with T1DM will be involved in this randomised controlled crossover trial.~Pregnant women at gestational week 16 and 35 (experimental phases 1 and 2, respectively), and non-pregnant peers once after recruitment (experimental phase 1), will undergo 3 experimental conditions within 10 days (random order): pre-meal exercise, post-meal exercise, and non-exercise meal.~Each experimental phase will entail participants attending 4 times to the research centre. Therefore, pregnant women will come to the research centre for a total of 8 study visits, while non-pregnant women will come only to 4 study visits. The acute exercise stimulus will consist of a well-controlled submaximal walking test. The standardised meal provided will consist of a mixed milkshake equivalent to the 35 % of their resting energy expenditure, being made up of approximately 45% carbohydrates, 35% fat, and 20% proteins. Postprandial glycaemic responses will be continuously monitored using last-generation glucose monitoring systems during the 10-day period. Immunometabolic markers (e.g., lipids, cytokines) will be determined in maternal blood and placenta samples.~The MERIT1D study will contribute to the understanding of exercise timing in T1DM and pregnancy, and its underlying mechanisms. This will translate into a better clinical prediction, diagnosis, prognosis and treatment of glycaemic dysregulations, and into more effective exercise programmes for pregnant and non-pregnant women with T1DM.
Poor glycaemic control in pregnancy is a major factor leading to obstetric complications and future maternal-offspring diseases. This phenomenon is evidenced in women with type 1 diabetes (T1DM), and is worrisome since it is aggravating the disease burden of this and next generations.~Exercise is a promising tool to improve glucose control during pregnancy and thus avoid adverse consequences.~The MERIT1D study will explore when is exercise (before or after lunch) more effective to improve postprandial glycaemic control in pregnant and non-pregnant women (of reproductive age) with T1DM, and the mechanisms underlying these metabolic responses.