Hello,
Without examination confirmation of a diagnosis is tough but frequent urination(polyuria) can be due to
diabetes mellitus.Other possibilities are
diabetes insipidus,glomerulonephritis, pyelonephritis(inflammation of the kidneys),urinary tract infection,hypercalcemia,hypokalemia(low potassium),hyperthyroidism,hyperparathyroidism,diuretic drugs and benign hyperplasia of the prostate(in males).