b12 injections and type 2 diabetes Metformin can cause vitamin deficiency in diabetics Why Do I Feel Worse

The cardiovascular and respiratory side effects include chest pain, tachycardia (increased heart rate), heart palpitations, low blood pressure, and chest tightness, cough with or without production of pink frothy sputum, wheezing and difficulty breathing

By attenuating NNMT activity, 5Amino1MQ has been observed in preclinical settings to elevate NAD+ availability, enhance metabolic flux, and upregulate downstream signaling programs associated with cellular stress responses and energy expenditure (e.g., SIRT1)

buccal, gingival, sublingual)] or rectal route

You don't say why you have been advised to have the injections, Do you have any of the below list of symptoms