Multiple factors increase diabetes risk. Diet is only one of them. Here below is evidence-based information:
Numerous risk factors like overweight or obesity, unhealthy diet, physical inactivity, high blood pressure, enhanced cholesterol levels, smoking, gene dysfunction can cause diabetes. Racial factors also have been found to strengthen risk. (Feskens et al., 1989; Choi et al., 2001; Salman. I et al., 2013; Knowler et al.,1990)
Obesity and body fat distribution are risk factors for cardiovascular disease and diabetes. Disturbed liver function and increased levels of lactate are prime risk factors. These serve as indicators of the body’s impaired ability to metabolize glucose. (Ohlson et al., 1988)
Diet management is central to diabetes treatment. The best diet for people with diabetes is an extensively studied subject. (Elhayany et al., 2010)
A meal that has been subject to high heat is a factor that increases the risk of type 2 diabetes and cardiovascular diseases. Steam cook food is better than high heat-treated foods. (Birloez-Aragon et al., 2010)
A complex set of factors triggers diabetes, and I would caution simplistic explanations.