In a sampled data system, the sampling rate should fulfill the Nyquist criterion. Respectively, if the sampling rate is 1/min, there should be no intermittent signal variations, or the sample rate has been selected inadequately.
A sampling rate decimation can take place in the data path if appropriate, but it would involve a decimation filter.
Seriously, I can't imagine that it's reasonable to use such a low sampling rate for your data, whatever the signal bandwidth is. As explained before, the sampling rate acts as a scaling factor in the differentiator, but you are free to implement a differentiator time constant of your choice independent of the sampling rate.