In one embodiment, a nuclear magnetic resonance (NMR) apparatus is described. The example NMR apparatus includes a first field generator configured to apply a first magnetic field to a sample (e.g., blood, interstitial fluid). A pulse generator is configured to provide a radio frequency (RF) pulse sequence. The pulse sequence may include a first RF pulse and a second RF pulse. The frequency of the RF pulses is chosen to produce an NMR signal associated with a specific chemical species (e.g., glucose) in the sample. A phase logic is configured to measure the decay of the NMR signal by measuring the phase differences that have accumulated between the spins of the nuclei of the chemical species in the sample. A calculation logic is configured to measure the amount of the chemical species in the sample.
