HI Thank for asking to HCM The chances of inheritance incidence in case of diabetes and thyroid disease is fairly enough,,it is gene related disease some mituation of gene are there,, hypothyroidism, hyperthyroidism, euthyroid,, patient may get diabetic coma and other systemic disease too, in case of thyroid metabolic function get disturbed badly and consequences would be bad,,the kid of father and mother having diabetes and thyroid may get disease chances are more,,,Biochemistry of blood is the only way to confirm it,,,,yes this if these two disease not at all treated then can be fatal,,,,no it does not alter your life style if treatment being taken properly,,, type 1, type 2 are main diabetes other are pregnancy induced functionally related insipidus, variably symptoms are there, hope this will help you have nice day.