Karvonen M, Jäntti V, Muntoni S, Stabilini M, Stabilini L, Muntoni S, Tuomilehto J
Department of Epidemiology and Health Promotion, National Public Health Institute, Helsinki, Finland.
Diabetes Care. 1998 Jul;21(7):1101-9. doi: 10.2337/diacare.21.7.1101.
To examine the seasonal pattern for the clinical onset of IDDM in Finland and Sardinia, two areas where the incidence of IDDM is the highest in the world, and to determine the effect of climate and temperature on the clinical onset of IDDM.
Analysis of seasonality for the diagnosis of IDDM was based on 1,405 cases in Finland and 425 cases in Sardinia diagnosed at < or = 14 years of age from 1989 to 1992. The average annual incidence of IDDM was 36.4/100,000 in Finland and 34.4/100,000 in Sardinia. Seasonal patterns were estimated presenting the data as short Fourier series up to three harmonics together with a possible linear trend. Likelihood ratio tests and Akaike's information criterion were used to determine the number of harmonics necessary to model the seasonal pattern. Seasonal patterns in both countries were compared between sexes and between the three 5-year age-groups, each controlling for the other's effect.
In both countries, a significant seasonal pattern during a calendar year was found for the sexes combined and for two age-groups (0-9 and 10-14 years). In Sardinia, two distinct cycles were found in the younger age-group, with a decreased incidence during May through August and an increased incidence during the autumn months. Two cycles were apparent in the older age-group, with the nadir occurring during June through September. In Finland, one cycle was found in the younger age-group, with a decreased incidence in June. In the older age-group, there were two distinct cycles, with a decreased incidence in June and in the September through December period.
Differences between Finland and Sardinia in the seasonal pattern for the incidence of newly diagnosed IDDM cannot be explained by differences in climate, temperature, a longer warm period in Sardinia, or other climatic phenomena. The results do not provide evidence in favor of a specific viral etiology of IDDM. It may be suggested that there are triggering events at certain times, but they are likely to be unspecific. Nevertheless, why the incidence of IDDM in these two populations is equally high despite differences in climate, environment, and genetic background remains an unsolved question.
研究芬兰和撒丁岛（世界上1型糖尿病发病率最高的两个地区）1型糖尿病临床发病的季节性模式，并确定气候和温度对1型糖尿病临床发病的影响。
对1989年至1992年期间在芬兰诊断的1405例1型糖尿病病例和在撒丁岛诊断的425例1型糖尿病病例（年龄≤14岁）进行季节性分析。芬兰1型糖尿病的年平均发病率为36.4/10万，撒丁岛为34.4/10万。通过将数据表示为高达三个谐波的短傅里叶级数以及可能的线性趋势来估计季节性模式。使用似然比检验和赤池信息准则来确定模拟季节性模式所需的谐波数量。对两国的季节性模式在性别之间以及三个5岁年龄组之间进行比较，每个组都控制了对方的影响。
在两国，合并性别以及两个年龄组（0 - 9岁和10 - 14岁）在日历年期间均发现了显著的季节性模式。在撒丁岛，较年轻年龄组发现了两个不同的周期，5月至8月发病率下降，秋季发病率上升。较年长年龄组有两个明显的周期，最低点出现在6月至9月。在芬兰，较年轻年龄组发现一个周期，6月发病率下降。在较年长年龄组，有两个不同的周期，6月以及9月至12月期间发病率下降。
芬兰和撒丁岛新诊断的1型糖尿病发病率季节性模式的差异不能用气候、温度、撒丁岛较长的温暖期或其他气候现象的差异来解释。结果未提供支持1型糖尿病特定病毒病因的证据。可能表明在某些时候存在触发事件，但它们可能是非特异性的。然而，尽管气候、环境和遗传背景存在差异，这两个人群中1型糖尿病的发病率为何同样高仍是一个未解决的问题。
