Hello, I m afraid there are not many alternatives for constipation. You haven t mentioned how severe your diabetes is. Do you take insulin? Some blood glucose measurements would have helped... I would suggest eating fiber and drinking water (which you already do) AND walking a lot (unless forbidden by your doctor for medical reasons). If you walk in the morning right after breakfast you can help your blood glucose get back to normal range since morning measurements are usually the problem in gestational diabetes. You could eat prunes. Eating the whole fruit is better than drinking prune juice regarding blood glucose levels elevation and for the constipation itself. If you are on insulin you could compensate additional carbohydrate intake with increased dosage. Please remember that pregnancy is a special condition that dietary restrictions should be minimal. You need to take enough calories for your baby but you also need to take your insulin if your blood sugar gets higher than the desired levels. I wish you the best for you and your baby! If you have further questions, please ask again! Kind Regards!