Personally I don't advocate any drink replacement diet regieme, as it doesn't teach people about the impact of foods... I suspect in your case whats happened is that the carbs in the drink, combined with the carbs from fruit and vegetables have been a light higher than you think!
Far better to learn and understand how differnt foods impact on you personally, what are good changes to make both in type and portion size of a meal/snack this generally leads to a much more successful out come...
I would speak to your GP/DSN as they have access to your medical information always important, but also ask to see a dietitian... So that you can restrict carbs safely as it's all about working out the amount of carbs you actually require or in the case of the diabetic, how many you can tollerate and what types you can tollerate..
Problem is the more you restrict foods/types the more you tend to crave it.. And the harder it can be to stick to the new diet without falling off the wagon... So need to set a achieveable small goal which works towards the ultimate goal..
But do ask for a test strip prescription, say that you want these to help you indentify the foods that aren't doing you any good, and those that are able to eat without impacting on your glucose levels, this will enable you to know why you need to make the lifestyle changes etc,.