You can try this:
diabetes_data = pd.DataFrame(diabetes['data'])
diabetes_target = pd.DataFrame(diabetes['target'])
df_c = pd.concat([diabetes_data, diabetes_target], axis=1)
print(df_c)
0 1 2 3 4 5 6 7 8 9 0
0 0.038076 0.050680 0.061696 0.021872 -0.044223 -0.034821 -0.043401 -0.002592 0.019908 -0.017646 151.0
1 -0.001882 -0.044642 -0.051474 -0.026328 -0.008449 -0.019163 0.074412 -0.039493 -0.068330 -0.092204 75.0
2 0.085299 0.050680 0.044451 -0.005671 -0.045599 -0.034194 -0.032356 -0.002592 0.002864 -0.025930 141.0
3 -0.089063 -0.044642 -0.011595 -0.036656 0.012191 0.024991 -0.036038 0.034309 0.022692 -0.009362 206.0
4 0.005383 -0.044642 -0.036385 0.021872 0.003935 0.015596 0.008142 -0.002592 -0.031991 -0.046641 135.0
.. ... ... ... ... ... ... ... ... ... ... ...
437 0.041708 0.050680 0.019662 0.059744 -0.005697 -0.002566 -0.028674 -0.002592 0.031193 0.007207 178.0
438 -0.005515 0.050680 -0.015906 -0.067642 0.049341 0.079165 -0.028674 0.034309 -0.018118 0.044485 104.0
439 0.041708 0.050680 -0.015906 0.017282 -0.037344 -0.013840 -0.024993 -0.011080 -0.046879 0.015491 132.0
440 -0.045472 -0.044642 0.039062 0.001215 0.016318 0.015283 -0.028674 0.026560 0.044528 -0.025930 220.0
441 -0.045472 -0.044642 -0.073030 -0.081414 0.083740 0.027809 0.173816 -0.039493 -0.004220 0.003064 57.0
To see all the keys in the diabetes data:
print(diabetes.keys())
dict_keys(['data', 'target', 'DESCR', 'feature_names', 'data_filename', 'target_filename'])