It is claimed that consumption of dairy food lowers risk for type 2 diabetes. The body of evidence does not support that claim. For example, this study:

Consumption of dairy products and associations with incident diabetes, CHD and mortality in the Whitehall II study, British Journal of Nutrition, February 2013

Found no relationship between dairy consumption (of any kind) and type 2 diabetes.

Few prospective studies have examined the effects of different types of dairy food on the risks of type 2 diabetes, CHD and mortality. We examined whether intakes of total dairy, high-fat dairy, low-fat dairy, milk and fermented dairy products were related to these outcomes in the Whitehall II prospective cohort study.

At baseline, dairy consumption was assessed by FFQ [Food Frequency Questionnaire] among 4526 subjects (72% men) with a mean age 56 (sd 6) years. Death certificates and medical records were used to ascertain CHD mortality and non-fatal myocardial infarction. Incident diabetes was detected by the oral glucose tolerance test or self-report. Incidence data were analysed using Cox proportional hazards models, adjusted for lifestyle and dietary factors.

During approximately 10 years of follow-up, 273 diabetes, 323 CHD and 237 all-cause mortality cases occurred. In multivariable models, intakes of total dairy and types of dairy products were not significantly associated with incident diabetes or CHD (all P values for trend >0·1).

In conclusion, intakes of total dairy and types of dairy products showed no consistent relationship with incident diabetes, CHD or all-cause mortality.

This was a good study … prospective (not cross-section or meta-analysis), long follow-up (10 years), large number of participants, and the relationship remained significant even after adjusting for confounders. I’ve seen that last factor (significance remaining in multivariable models) glossed over in the conclusion of other studies.

Note: Dairy consumption, however, does increase the risk for type 1 diabetes:
Significance of cow’s milk protein antibodies as risk factor for childhood IDDM: interaction with dietary cow’s milk intake and HLA-DQB1 genotype. Diabetologia, 1998