The decrease of Hb was positively correlated with the baseline HbA1c level according to univariate analysis (r = 0.31, p < 0.001), suggesting that chronic hyperglycemia-induced osmotic diuresis may lead to dehydration and elevation of Hb, which may decrease following alleviation of dehydration due to improvement of hyperglycemia. The gene discussed is GSTM1; the disease is Hyperglycemia.