In non-diabetic persons MDMA does not have a significant effect on glucose blood levels. There are no specific studies on diabetic persons but, according to MDMA pharmacology, dramatic changes in glucose are not expected.
In fact, alcohol is the most altering glucose drug in diabetics. For the rest of substances, it is more important “what are you doing” that “what substance did you take”. If you are dancing, doing exhausting exercise or you forget to eat are important aspects that can affect glycaemia. Some drugs make you hungry (cannabis), other diminish appetite (stimulants).
Most people feel like, on MDMA, it is easy to keep control on what you feel, what you think and what you do (or at least easier than other drugs). But the positive mood could make you feel forgetful and carefree. As MDMA effects last for 4-6 hours, one possible strategy is to set an alarm clock in hour 2-4 to remind you of test your sugar. I think with that it should be enough. If you are with some friends that know what you are doing it should be great. You should use moderate doses first times (60-80 mg) and be cautious with dosage in general (not over 120 mg) as diabetes can affect cardiovascular health. One important thing to remember is that MDMA decreases appetite: you should keep with you sweat soft food as milkshakes or fruit.
Some diabetic MDMA users have told me that MDMA makes them feel more conscious about their own body, so they can notice better if there is hyper or hypoglycaemias. On the other hand, ketamine is a drug not recommendable for diabetics, as it alters self-perception of body.
I don´t know how long have you been diagnosed of diabetes, but if it is a recent diagnosis you should wait to know well how to use insulin and “get used” to your condition and then after experiment with substances. I think worries and paranoias are less probable with MDMA than psychedelics. But as you learn to live a normal life with diabetes worries will disappear.