Correlation is suggestive at best. I have 3 biology degrees. The actual research on this, I've done, and I've only come across this suggestion once. Once. Once is not a statistic. It's a datum at best.
Plenty of medical assumptions on the forefront of Diabetes itself, are completely wrong. As well, plenty of people employed by associations and charities for such illnesses that seem to be 'helping'. More evidence by online science analysts indicating lifestyle theraputics are completely backwards, backed by lots of data. I've lost 14 kg by diet alone within 3 months, second time around, completely against this wonderful industry-pushed 'food pyramic'. There's your 'medical studies'.