I think that the symptoms that you are experiencing are quite concerning and I recommend getting in to see your doctors
">primary care doctor or going to the emergency room immediately. This is because there is a possibility that this is a serious skin infection, called cellulitis, which having diabetes puts you at higher risk of developing. Other concerning symptoms include the fact that the blisters seem to be spreading and that they are making it difficult to stand. Additional concerning symptoms would include fever
and red or painful skin under the blisters.
At the emergency room or in your doctor's office, they will be able to examine the skin closely to determine if there is any evidence of skin infection. If so you may need antibiotics. If the infection is mild, it can probably be controlled with oral antibiotics, however some severe cases of these skin infections do require hospitalization for IV antibiotics.
If it turns out not to be a serious skin infection, then it is possible that you have contracted a fungal infection, which is again very common in people with diabetes, or that you simply have skin irritation from moisture in the area. Nevertheless, start by seeking urgent medical evaluation.