FGF2 and diabetes mellitus: The effect of BDNF on metabolism and synaptic plasticity appears to involve IGF1 and FGF2. At normal concentrations, IGF1 supports nerve growth and differentiation, neurotransmitter synthesis and release, as well as synaptic plasticity, however at substantially higher levels IGF1 is positively correlated with many cancers, diabetes and neurodegeneration (Rabinovsky, 2004).