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AIMS/HYPOTHESIS: We tested the hypothesis that dietary acid load may increase the risk of type 2 diabetes, and studied the association between acid load and insulin sensitivity as a possible mechanism involved.

METHODS: An observational survey with prospective follow-up including 911 non-diabetic Swedish men aged 70-71 years was carried out. The gold standard euglycaemic-hyperinsulinaemic clamp technique and the OGTT were used to determine insulin sensitivity and beta cell function, respectively. Diabetes incidence was assessed during 18 years of follow-up. Renal function was estimated from serum cystatin C concentrations. Dietary acid load was calculated as potential renal acid load (PRAL) and net endogenous acid production (NEAP) algorithms from 7 day food records. Adequate dietary reporters were identified by Goldberg cut-offs.

RESULTS: PRAL and NEAP were not associated with insulin sensitivity or beta cell function. Underlying kidney function or consideration of dietary adequate reporters did not modify these null findings. During follow-up, 115 new cases of diabetes were validated. Neither PRAL nor NEAP was associated with diabetes incidence.

CONCLUSIONS/INTERPRETATION: Our results do not support the hypothesis that dietary acid load influences insulin sensitivity, beta cell function or diabetes risk. Interventional studies modifying acid-base dietary intake are needed to further elucidate a possible role of acid load in the development of type 2 diabetes.