In this paper, the authors establish some asymptotic formulas and two-sided inequalities for the ratio of the gamma function in terms of the digamma function. Considering the application of the gamma function to central Bernoulli coefficients, the authors give some better approximations and two-sided inequalities of central Bernoulli coefficients. Finally, for demonstrating the superiority of our results, some numerical computations are given. Keywords Digamma function • Ratio of the gamma function • Approximation • Power series expansion • Continued fraction • Central Bernoulli coefficients • Two-sided inequalities Mathematics Subject Classification 33B15 • 26D15 • 41A25